U.S. patent application number 16/231325 was filed with the patent office on 2019-06-27 for grating waveguide combiner for optical engine.
The applicant listed for this patent is NORTH INC.. Invention is credited to Douglas Raymond Dykaar, Syed Moez Haque, Rony Jose James, Martin Joseph Kiik, Stefan Mohrdiek, Jorg Pierer.
Application Number | 20190196204 16/231325 |
Document ID | / |
Family ID | 66950184 |
Filed Date | 2019-06-27 |
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United States Patent
Application |
20190196204 |
Kind Code |
A1 |
Pierer; Jorg ; et
al. |
June 27, 2019 |
GRATING WAVEGUIDE COMBINER FOR OPTICAL ENGINE
Abstract
Systems, devices, and methods of manufacturing optical engines
and laser projectors that are well-suited for use in wearable
heads-up displays (WHUDs) are described. Generally, the optical
engines of the present disclosure integrate a plurality of laser
diodes (e.g., 3 laser diodes, 4 laser diodes) within a single,
hermetically or partially hermetically sealed, encapsulated
package. A grating waveguide combiner comprising a plurality of
waveguides having grating couplers thereon may be used to combine
beams of light emitted by the plurality of laser diodes into a
coaxially superimposed aggregate beam. Such optical engines may
have advantages over existing designs including, for example,
smaller volumes, better manufacturability, faster modulation speed,
etc. WHUDs that employ such optical engines and laser projectors
are also described.
Inventors: |
Pierer; Jorg; (Alpnach,
CH) ; James; Rony Jose; (Alpnach, CH) ;
Mohrdiek; Stefan; (Affoltern am Albis, CH) ; Kiik;
Martin Joseph; (Kitchener, CA) ; Haque; Syed
Moez; (Kitchener, CA) ; Dykaar; Douglas Raymond;
(Waterloo, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
NORTH INC. |
Kitchener |
|
CA |
|
|
Family ID: |
66950184 |
Appl. No.: |
16/231325 |
Filed: |
December 21, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62609870 |
Dec 22, 2017 |
|
|
|
62620600 |
Jan 23, 2018 |
|
|
|
62760835 |
Nov 13, 2018 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
G02B 6/4206 20130101;
H01S 5/0228 20130101; G02B 6/4215 20130101; G02B 2027/0116
20130101; G02B 6/12004 20130101; H01S 5/005 20130101; H01S 5/02268
20130101; H01S 5/02272 20130101; H01S 5/02288 20130101; H01S
5/02292 20130101; H01S 5/4012 20130101; G02B 27/1006 20130101; G02B
27/0176 20130101; H01S 5/4093 20130101; G02B 6/4249 20130101; G02B
27/0172 20130101; G02B 2027/0178 20130101; H01S 5/0071 20130101;
G02B 26/101 20130101; G02B 2006/12164 20130101; G02B 27/141
20130101; G02B 2027/015 20130101; G02B 6/4214 20130101; G02B
2006/12107 20130101; G02B 6/124 20130101 |
International
Class: |
G02B 27/01 20060101
G02B027/01; H01S 5/40 20060101 H01S005/40; H01S 5/022 20060101
H01S005/022; G02B 6/12 20060101 G02B006/12; G02B 6/124 20060101
G02B006/124 |
Claims
1. An optical engine, comprising: a base substrate; a plurality of
laser diodes, each of the plurality of laser diodes bonded directly
or indirectly to the base substrate; at least one laser diode
driver circuit operatively coupled to the plurality of laser diodes
to selectively drive current to the plurality of laser diodes; a
plurality of collimation lenses, each of the plurality of
collimation lenses positioned proximate a respective one of the
plurality of laser diodes collimates light emitted therefrom; a cap
comprising at least one wall and at least one optical window that,
together with the base substrate, define an interior volume sized
and dimensioned to receive at least the plurality of laser diodes
and the plurality of collimation lenses, the cap being bonded to
the base substrate to provide a hermetic or partially hermetic seal
between the interior volume of the cap and a volume exterior to the
cap, and the optical window positioned and oriented to allow beams
of light emitted from the plurality of laser diodes through the
collimation lenses to exit the interior volume; and a grating
waveguide combiner positioned proximate the optical window of the
cap, the grating waveguide combiner comprising a plurality of input
grating couplers and at least one output grating coupler, in
operation, the grating waveguide combiner receives a plurality of
beams of light at the respective plurality of input grating
couplers and combines the plurality of beams of light to provide a
collimated aggregated beam of light at the output grating
coupler.
2. The optical engine of claim 1 wherein the grating waveguide
combiner comprises a first grating waveguide and a second grating
waveguide.
3. The optical engine of claim 2 wherein each of the first and
second grating waveguides includes at least two input grating
couplers.
4. The optical engine of claim 1 wherein the grating waveguide
combiner comprises at least four waveguides.
5. The optical engine of claim 1 wherein the plurality of
collimation lenses are formed as a micro-optic lens array.
6. The optical engine of claim 1 wherein the plurality of
collimation lenses are bonded to the base substrate.
7. The optical engine of claim 1 wherein the grating waveguide
combiner is bonded to the base substrate proximate the optical
window of the cap.
8. The optical engine of claim 1, further comprising: a common
collimation lens positioned and oriented to receive and collimate
the aggregate beam of light from the output grating coupler of the
grating waveguide combiner.
9. The optical engine of claim 8 wherein the common collimation
lens comprises an achromatic lens.
10. The optical engine of claim 8 wherein the common collimation
lens comprises an apochromatic lens.
11. The optical engine of claim 1, further comprising at least one
diffractive optical element positioned and oriented to receive the
aggregate beam of light, in operation, the at least one diffractive
optical element provides wavelength dependent focus correction for
the aggregate beam of light.
12. The optical engine of claim 1, further comprising: a plurality
of chip submounts bonded to the base substrate, wherein each of the
laser diodes are bonded to a corresponding one of the plurality of
chip submounts.
13. The optical engine of claim 1 wherein the plurality of laser
diodes includes a red laser diode to provide a red laser light, a
green laser diode to provide a green laser light, a blue laser
diode to provide a blue laser light, and an infrared laser diode to
provide infrared laser light.
14. The optical engine of claim 1 wherein the base substrate is
formed from at least one of low temperature co-fired ceramic
(LTCC), aluminum nitride (AlN), or alumina.
15. The optical engine of claim 1 wherein the at least one laser
diode driver circuit is bonded to a first surface of the base
substrate, and the plurality of laser diodes and the cap are bonded
to a second surface of the base substrate, the second surface of
the base substrate opposite the first surface of the base
substrate.
16. The optical engine of claim 1 wherein the at least one laser
diode driver circuit, the plurality of laser diodes, and the cap
are bonded to a first surface of the base substrate.
17. The optical engine of claim 1 wherein the plurality of laser
diodes and the cap are bonded to the base substrate, and the at
least one laser diode driver circuit is bonded to another substrate
separate from the base substrate.
18. The optical engine of claim 1 wherein each of the laser diodes
comprises one of an edge emitter laser or a vertical-cavity
surface-emitting laser (VCSEL).
Description
BACKGROUND
Technical Field
[0001] The present disclosure is generally directed to systems,
devices, and methods relating to optical engines, for example,
optical engines for laser projectors used in wearable heads-up
displays or other applications.
Description of the Related Art
[0002] A projector is an optical device that projects or shines a
pattern of light onto another object (e.g., onto a surface of
another object, such as onto a projection screen) in order to
display an image or video on that other object. A projector
necessarily includes a light source, and a laser projector is a
projector for which the light source comprises at least one laser.
The at least one laser is temporally modulated to provide a pattern
of laser light and usually at least one controllable mirror is used
to spatially distribute the modulated pattern of laser light over a
two-dimensional area of another object. The spatial distribution of
the modulated pattern of laser light produces an image at or on the
other object. In conventional scanning laser projectors, at least
one controllable mirror may be used to control the spatial
distribution, and may include: a single digital micromirror (e.g.,
a microelectromechanical system ("MEMS") based digital micromirror)
that is controllably rotatable or deformable in two dimensions, or
two digital micromirrors that are each controllably rotatable or
deformable about a respective dimension, or a digital light
processing ("DLP") chip comprising an array of digital
micromirrors.
[0003] In a conventional laser projector comprising an RGB
(red/green/blue) laser module with a red laser diode, a green laser
diode, and a blue laser diode, each respective laser diode may have
a corresponding respective focusing lens. Each of the laser diodes
of a laser module are typically housed in a separate package (e.g.,
a TO-38 package or "can"). The relative positions of the laser
diodes, the focusing lenses, and the at least one controllable
mirror are all tuned and aligned so that each laser beam impinges
on the at least one controllable mirror with substantially the same
spot size and with substantially the same rate of convergence (so
that all laser beams will continue to have substantially the same
spot size as they propagate away from the laser projector towards,
e.g., a projection screen). In a conventional laser projector, it
is usually possible to come up with such a configuration for all
these elements because the overall form factor of the device is not
a primary design consideration. However, in applications for which
the form factor of the laser projector is an important design
element, it can be very challenging to find a configuration for the
laser diodes, the focusing lenses, and the at least one
controllable mirror that sufficiently aligns the laser beams (at
least in terms of spot size, spot position, and rate of
convergence) while satisfying the form factor constraints.
[0004] A head-mounted display is an electronic device that is worn
on a user's head and, when so worn, secures at least one electronic
display within a viewable field of at least one of the user's eyes,
regardless of the position or orientation of the user's head. A
wearable heads-up display is a head-mounted display that enables
the user to see displayed content but also does not prevent the
user from being able to see their external environment. The
"display" component of a wearable heads-up display is either
transparent or at a periphery of the user's field of view so that
it does not completely block the user from being able to see their
external environment. A "combiner" component of a wearable heads-up
display is the physical structure where display light and
environmental light merge as one within the user's field of view.
The combiner of a wearable heads-up display is typically
transparent to environmental light but includes some optical
routing mechanism to direct display light into the user's field of
view.
[0005] Examples of wearable heads-up displays include: the Google
Glass.RTM., the Optinvent Ora.RTM., the Epson Moverio.RTM., and the
Sony Glasstron.RTM., just to name a few.
[0006] The optical performance of a wearable heads-up display is an
important factor in its design. When it comes to face-worn devices,
users also care a lot about aesthetics and comfort. This is clearly
highlighted by the immensity of the eyeglass (including sunglass)
frame industry. Independent of their performance limitations, many
of the aforementioned examples of wearable heads-up displays have
struggled to find traction in consumer markets because, at least in
part, they lack fashion appeal or comfort. Most wearable heads-up
displays presented to date employ relatively large components and,
as a result, are considerably bulkier, less comfortable and less
stylish than conventional eyeglass frames.
Direct Laser Writing
[0007] Femtosecond laser micro-machining is a direct-laser-write
and rapid prototyping technique that provides great potential for
optical device fabrication. Strong focusing of femtosecond laser
light into transparent glass can induce positive refractive index
modifications up to 0.01 refractive index units (MU) within the
material and without surface damage. Since then, ultrafast
(femto/pico-second) lasers have been shown to enable flexible 3D
structuring of various glasses, and has led to the demonstration of
many types of optical devices (waveguides, couplers, Bragg
gratings, waveplates, etc.) that serve as building blocks for 3D
optical circuits.
[0008] Direct-laser-writing uses ultrashort laser pulses to confine
strong nonlinear optical interactions that may induce, for example,
positive or negative refractive index changes in bulk transparent
materials for creating optical waveguides (WGs). The mechanisms by
which direct-laser-write modifications occur include, but are not
limited to, multiphoton ionization, avalanche ionization,
electron-atom collisions, plasma interactions, thermal effects
(e.g. diffusion, heat accumulation), energy dissipation, and
material cooling leading to inhomogeneous solidification. For
direct-laser-writing waveguides, waveguide performance can be tuned
and optimized by, but not limited to, the writing laser's
properties (pulse duration, pulse temporal shape, bandwidth and
shape, pulse repetition rate, wavelength, polarization, and beam
spatial shape) and the focusing conditions (lens numerical
aperture, air/liquid immersion, translation direction and
speeds).
BRIEF SUMMARY
[0009] According to one or more implementations of the present
disclosure, an optical engine may be summarized as including: a
base substrate; a plurality of laser diodes, each of the plurality
of laser diodes bonded directly or indirectly to the base
substrate; at least one laser diode driver circuit operatively
coupled to the plurality of laser diodes to selectively drive
current to the plurality of laser diodes; a plurality of
collimation lenses, each of the plurality of collimation lenses
positioned proximate a respective one of the plurality of laser
diodes collimates light emitted therefrom; a cap comprising at
least one wall and at least one optical window that, together with
the base substrate, define an interior volume sized and dimensioned
to receive at least the plurality of laser diodes and the plurality
of collimation lenses, the cap being bonded to the base substrate
to provide a hermetic or partially hermetic seal between the
interior volume of the cap and a volume exterior to the cap, and
the optical window positioned and oriented to allow beams of light
emitted from the plurality of laser diodes through the collimation
lenses to exit the interior volume; and a grating waveguide
combiner positioned proximate the optical window of the cap, the
grating waveguide combiner comprising a plurality of input grating
couplers and at least one output grating coupler, in operation, the
grating waveguide combiner receives a plurality of beams of light
at the respective plurality of input grating couplers and combines
the plurality of beams of light to provide a collimated aggregated
beam of light at the output grating coupler.
[0010] The grating waveguide combiner may include a first grating
waveguide and a second grating waveguide. Each of the first and
second grating waveguides may include at least two input grating
couplers. The grating waveguide combiner may include at least four
waveguides. The plurality of collimation lenses may be formed as a
micro-optic lens array. The plurality of collimation lenses may be
bonded to the base substrate. The grating waveguide combiner may be
bonded to the base substrate proximate the optical window of the
cap.
[0011] The optical engine may further include a common collimation
lens positioned and oriented to receive and collimate the aggregate
beam of light from the output grating coupler of the grating
waveguide combiner. The common collimation lens may include an
achromatic lens or an apochromatic lens.
[0012] The optical engine may further include at least one
diffractive optical element positioned and oriented to receive the
aggregate beam of light, in operation, the at least one diffractive
optical element may provide wavelength dependent focus correction
for the aggregate beam of light.
[0013] The optical engine may further include a plurality of chip
submounts bonded to the base substrate, wherein each of the laser
diodes are bonded to a corresponding one of the plurality of chip
submounts. The plurality of laser diodes may include a red laser
diode to provide a red laser light, a green laser diode to provide
a green laser light, a blue laser diode to provide a blue laser
light, and an infrared laser diode to provide infrared laser light.
The base substrate may be formed from at least one of low
temperature co-fired ceramic (LTCC), aluminum nitride (AlN), or
alumina.
[0014] The at least one laser diode driver circuit may be bonded to
a first surface of the base substrate, and the plurality of laser
diodes and the cap may be bonded to a second surface of the base
substrate, the second surface of the base substrate opposite the
first surface of the base substrate. The at least one laser diode
driver circuit, the plurality of laser diodes, and the cap may be
bonded to a first surface of the base substrate. The plurality of
laser diodes and the cap may be bonded to the base substrate, and
the at least one laser diode driver circuit may be bonded to
another substrate separate from the base substrate.
[0015] Each of the laser diodes may include one of an edge emitter
laser or a vertical-cavity surface-emitting laser (VCSEL).
[0016] According to one or more implementations of the present
disclosure, a laser projector may be summarized as including: an
optical engine, comprising: a base substrate; a plurality of laser
diodes, each of the plurality of laser diodes bonded directly or
indirectly to the base substrate; at least one laser diode driver
circuit operatively coupled to the plurality of laser diodes to
selectively drive current to the plurality of laser diodes; a
plurality of collimation lenses, each of the plurality of
collimation lenses positioned proximate a respective one of the
plurality of laser diodes collimates light emitted therefrom; a cap
comprising at least one wall and at least one optical window that,
together with the base substrate, define an interior volume sized
and dimensioned to receive at least the plurality of laser diodes
and the plurality of collimation lenses, the cap being bonded to
the base substrate to provide a hermetic or partially hermetic seal
between the interior volume of the cap and a volume exterior to the
cap, and the optical window positioned and oriented to allow beams
of light emitted from the plurality of laser diodes through the
collimation lenses to exit the interior volume; and a grating
waveguide combiner positioned proximate the optical window of the
cap, the grating waveguide combiner comprising a plurality of input
grating couplers and at least one output grating coupler, in
operation, the grating waveguide combiner receives a plurality of
beams of light at the respective plurality of input grating
couplers and combines the plurality of beams of light to provide a
collimated aggregated beam of light at the output grating coupler;
and at least one scan mirror positioned to receive the aggregate
beam of light output at the output grating coupler of the grating
waveguide combiner, the at least one scan mirror controllably
orientable to redirect the aggregate beam of light over a range of
angles.
[0017] The grating waveguide combiner may include a first grating
waveguide and a second grating waveguide. Each of the first and
second grating waveguides may include at least two input grating
couplers. The grating waveguide combiner may include at least four
waveguides.
[0018] The plurality of collimation lenses may be formed as a
micro-optic lens array. The plurality of collimation lenses may be
bonded to the base substrate. The grating waveguide combiner may be
bonded to the base substrate proximate the optical window of the
cap.
[0019] The optical engine of the laser projector may further
include a common collimation lens positioned and oriented to
receive and collimate the aggregate beam of light from the output
grating coupler of the grating waveguide combiner. The common
collimation lens may include an achromatic lens. The common
collimation lens may include an apochromatic lens.
[0020] The optical engine of the laser projector may further
comprise at least one diffractive optical element positioned and
oriented to receive the aggregate beam of light, in operation, the
at least one diffractive optical element may provide wavelength
dependent focus correction for the aggregate beam of light.
[0021] The optical engine of the laser projector may further
include a plurality of chip submounts bonded to the base substrate,
wherein each of the laser diodes are bonded to a corresponding one
of the plurality of chip submounts. The plurality of laser diodes
may include a red laser diode to provide a red laser light, a green
laser diode to provide a green laser light, a blue laser diode to
provide a blue laser light, and an infrared laser diode to provide
infrared laser light. The base substrate may be formed from at
least one of low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), or alumina.
[0022] The at least one laser diode driver circuit may be bonded to
a first surface of the base substrate, and the plurality of laser
diodes and the cap may be bonded to a second surface of the base
substrate, the second surface of the base substrate opposite the
first surface of the base substrate. The at least one laser diode
driver circuit, the plurality of laser diodes, and the cap may be
bonded to a first surface of the base substrate. The plurality of
laser diodes and the cap may be bonded to the base substrate, and
the at least one laser diode driver circuit may be bonded to
another substrate separate from the base substrate. Each of the
laser diodes may be one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL).
[0023] According to one or more implementations of the present
disclosure, a wearable heads-up display (WHUD) may be summarized as
including: a support structure that in use is worn on the head of a
user; a laser projector carried by the support structure, the laser
projector comprising: an optical engine, comprising: a base
substrate; a plurality of laser diodes, each of the plurality of
laser diodes bonded directly or indirectly to the base substrate;
at least one laser diode driver circuit operatively coupled to the
plurality of laser diodes to selectively drive current to the
plurality of laser diodes; a plurality of collimation lenses, each
of the plurality of collimation lenses positioned proximate a
respective one of the plurality of laser diodes collimates light
emitted therefrom; a cap comprising at least one wall and at least
one optical window that, together with the base substrate, define
an interior volume sized and dimensioned to receive at least the
plurality of laser diodes and the plurality of collimation lenses,
the cap being bonded to the base substrate to provide a hermetic or
partially hermetic seal between the interior volume of the cap and
a volume exterior to the cap, and the optical window positioned and
oriented to allow beams of light emitted from the plurality of
laser diodes through the collimation lenses to exit the interior
volume; and a grating waveguide combiner positioned proximate the
optical window of the cap, the grating waveguide combiner
comprising a plurality of input grating couplers and at least one
output grating coupler, in operation, the grating waveguide
combiner receives a plurality of beams of light at the respective
plurality of input grating couplers and combines the plurality of
beams of light to provide a collimated aggregated beam of light at
the output grating coupler; and at least one scan mirror positioned
to receive the aggregate beam of light output at the output grating
coupler of the grating waveguide combiner, the at least one scan
mirror controllably orientable to redirect the aggregate beam of
light over a range of angles.
[0024] The grating waveguide combiner may include a first grating
waveguide and a second grating waveguide. Each of the first and
second grating waveguides may include at least two input grating
couplers. The grating waveguide combiner may include at least four
waveguides.
[0025] The plurality of collimation lenses may be formed as a
micro-optic lens array. The plurality of collimation lenses may be
bonded to the base substrate. The grating waveguide combiner may be
bonded to the base substrate proximate the optical window of the
cap.
[0026] The optical engine of the laser projector may further
include a common collimation lens positioned and oriented to
receive and collimate the aggregate beam of light from the output
grating coupler of the grating waveguide combiner. The common
collimation lens may include an achromatic lens or an apochromatic
lens.
[0027] The optical engine of the laser projector may further
comprise at least one diffractive optical element positioned and
oriented to receive the aggregate beam of light, in operation, the
at least one diffractive optical element may provide wavelength
dependent focus correction for the aggregate beam of light.
[0028] The optical engine of the laser projector may further
include a plurality of chip submounts bonded to the base substrate,
wherein each of the laser diodes are bonded to a corresponding one
of the plurality of chip submounts. The plurality of laser diodes
may include a red laser diode to provide a red laser light, a green
laser diode to provide a green laser light, a blue laser diode to
provide a blue laser light, and an infrared laser diode to provide
infrared laser light. The base substrate may be formed from at
least one of low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), or alumina.
[0029] The at least one laser diode driver circuit may be bonded to
a first surface of the base substrate, and the plurality of laser
diodes and the cap may be bonded to a second surface of the base
substrate, the second surface of the base substrate opposite the
first surface of the base substrate. The at least one laser diode
driver circuit, the plurality of laser diodes, and the cap may be
bonded to a first surface of the base substrate. The plurality of
laser diodes and the cap may be bonded to the base substrate, and
the at least one laser diode driver circuit may be bonded to
another substrate separate from the base substrate. The plurality
of laser diodes and the cap may be bonded to the base substrate,
and the at least one laser diode driver circuit may be mounted to
the support structure of the WHUD.
[0030] Each of the laser diodes may be one of an edge emitter laser
or a vertical-cavity surface-emitting laser (VCSEL). The WHUD may
further include a processor communicatively coupled to the laser
projector to modulate the generation of light signals. The WHUD may
further include a transparent combiner carried by the support
structure and positioned within a field of view of the user, in
operation the transparent combiner directs laser light from an
output of the laser projector into the field of view of the
user.
[0031] According to one or more implementations of the present
disclosure, a method of manufacturing an optical engine may be
summarized as including: bonding a plurality of laser diodes
directly or indirectly to a base substrate; coupling at least one
laser diode driver circuit to the laser diodes, in operation the at
least one laser diode driver circuit selectively drives current to
the laser diodes; bonding a plurality of collimation lenses to the
base substrate proximate the plurality of laser diodes; bonding a
cap comprising at least one wall and at least one optical window to
the base substrate, the at least one wall, the at least one optical
window, and at least a portion of the base substrate together
delimit an interior volume sized and dimensioned to receive at
least the plurality of laser diodes and the plurality of
collimation lenses, the bonding of the cap to the base substrate
providing a hermetic or partially hermetic seal between the
interior volume of the cap and a volume exterior to the cap, and
the optical window positioned and oriented to allow light emitted
from the laser diodes through the collimation lenses to exit the
interior volume; and bonding a grating waveguide combiner proximate
the optical window of the cap, the grating waveguide combiner
comprising a plurality of input grating couplers and at least one
output grating coupler, in operation, the grating waveguide
combiner receives a plurality of beams of light at the respective
plurality of input grating couplers and combines the plurality of
beams of light to provide a collimated aggregated beam of light at
the output grating coupler.
[0032] Bonding a plurality of collimation lenses to the base
substrate may include bonding a micro-optic lens array to the base
substrate. The method may further include actively or passively
aligning the collimation lenses.
[0033] Bonding a grating waveguide combiner proximate the optical
window of the cap may include writing the plurality of input
grating couplers and at least one output grating coupler into a
waveguide medium, and subsequently bonding the waveguide medium
proximate the optical window of the cap. Bonding a grating
waveguide combiner proximate the optical window of the cap may
include bonding a writeable waveguide medium proximate the optical
window of the cap, and subsequently writing the plurality of input
grating couplers and at least one output grating coupler into the
waveguide medium.
[0034] The method may further include: bonding each of the laser
diodes indirectly to the base substrate by bonding each laser diode
to a respective chip submount; and bonding each chip submount to
the base substrate. Bonding each laser diode to a respective chip
submount may include bonding each laser diode to a respective chip
submount using a eutectic gold tin (AuSn) solder process. Bonding
each chip submount to the base substrate may include step-soldering
each chip submount to the base substrate. Bonding each chip
submount to the base substrate may include bonding each chip
submount to the base substrate using at least one of a reflow oven
process, thermosonic bonding, thermocompression bonding, transient
liquid phase (TLP) bonding, or laser soldering. Bonding each chip
submount to the base substrate may include bonding a chip submount
that has a red laser diode bonded thereto, bonding a chip submount
that has a green laser diode bonded thereto, bonding a chip
submount that has a blue laser diode bonded thereto, and bonding a
chip submount that has an infrared laser diode bonded thereto.
[0035] Coupling at least one laser diode driver circuit to the
laser diodes may include: bonding a plurality of electrical
connections to the base substrate, each electrical connection
coupled to a respective laser diode in the plurality of laser
diodes; providing a coupling between each of the plurality of
electrical connections and the at least one laser diode driver
circuit; and bonding an electrically insulating cover to the base
substrate over the plurality of electrical connections, and bonding
the cap to the base substrate may include bonding the cap to the
base substrate and the electrically insulating cover. Providing a
coupling between each of the plurality of electrical connections
and the at least one laser diode driver circuit may include:
bonding a plurality of electrical contacts to the base substrate,
each electrical contact coupled to a respective one of the
plurality of electrical connections; and providing a coupling
between each of the electrical contacts and the at least one laser
diode driver circuit.
[0036] Bonding the plurality of laser diodes directly or indirectly
to a base substrate may include bonding the laser diodes directly
or indirectly to a first surface of the base substrate, and bonding
a cap to the base substrate may include bonding a cap to the first
surface of the base substrate, and the method may further include
bonding the at least one laser diode driver circuit to a second
surface of the base substrate, the second surface of the base
substrate opposite the first surface of the base substrate. Bonding
the plurality of laser diodes directly or indirectly to a base
substrate may include bonding the laser diodes directly or
indirectly to a first surface of the base substrate, and bonding a
cap to the base substrate may include bonding a cap to the first
surface of the base substrate, and the method may further include
bonding the at least one laser diode driver circuit to the first
surface of the base substrate. Bonding a cap to the base substrate
may include bonding a cap to the base substrate using at least one
of a seam welding process, a laser assisted soldering process, or a
diffusion bonding process.
[0037] The method may further include positioning and orienting a
collimation lens to receive and collimate the aggregate beam of
light from the output facet of the photonic integrated circuit.
BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS
[0038] In the drawings, identical reference numbers identify
similar elements or acts. The sizes and relative positions of
elements in the drawings are not necessarily drawn to scale. For
example, the shapes of various elements and angles are not
necessarily drawn to scale, and some of these elements may be
arbitrarily enlarged and positioned to improve drawing legibility.
Further, the particular shapes of the elements as drawn, are not
necessarily intended to convey any information regarding the actual
shape of the particular elements, and may have been solely selected
for ease of recognition in the drawings.
[0039] FIG. 1A is a left side, sectional elevational view of an
optical engine, in accordance with the present systems, devices,
and methods.
[0040] FIG. 1B is a front side, sectional elevational view of the
optical engine also shown in FIG. 1A, in accordance with the
present systems, devices, and methods.
[0041] FIG. 2 is a flow diagram of a method of operating an optical
engine, in accordance with the present systems, devices, and
methods.
[0042] FIG. 3 is a schematic diagram of a wearable heads-up display
with a laser projector that includes an optical engine, and a
transparent combiner in a field of view of an eye of a user, in
accordance with the present systems, devices, and methods.
[0043] FIG. 4 is an isometric view of a wearable heads-up display
with a laser projector that includes an optical engine, in
accordance with the present systems, devices, and methods.
[0044] FIG. 5 is a flow diagram of a method of manufacturing an
optical engine, in accordance with the present systems, devices,
and methods.
[0045] FIG. 6 is a top plan view of a photonic integrated circuit
for wavelength multiplexing that includes a plurality of grating
couplers on a surface thereof, the photonic integrated circuit
followed by a common collimation lens and an optional diffractive
optical element, in accordance with the present systems, devices,
and methods.
[0046] FIG. 7 is a left side sectional elevational view of an
optical engine that includes a plurality of laser diodes inside a
hermetically or partially hermetically sealed package coupled to
the photonic integrated circuit of FIG. 6 for wavelength
multiplexing, and a common collimation lens and an optional
diffractive optical element, in accordance with the present
systems, devices, and methods.
[0047] FIG. 8 is a top plan view of a photonic integrated circuit
for wavelength multiplexing followed by a common collimation lens
and an optional diffractive optical element, in accordance with the
present systems, devices, and methods.
[0048] FIG. 9 is a left side sectional elevational view of an
optical engine that includes a plurality of laser diodes inside a
hermetically or partially hermetically sealed package coupled to a
photonic integrated circuit of FIG. 8 for wavelength multiplexing,
and a common collimation lens and an optional diffractive optical
element, in accordance with the present systems, devices, and
methods.
[0049] FIG. 10 is a schematic diagram of a laser writing system
which can be used to write photonic integrated circuits in
accordance with the present systems, devices, and methods.
[0050] FIG. 11 is a flow diagram of a method of manufacturing an
optical engine including writing a photonic integrated circuit, in
accordance with the present systems, devices, and methods.
[0051] FIGS. 12A, 12B, and 13 are schematic diagrams of laser
writing systems which can be used to write photonic integrated
circuits in writeable glass already bonded to a substrate or
circuit, according to at least two illustrated implementations.
[0052] FIG. 14 is a left side sectional elevational view of an
optical engine that includes a plurality of laser diodes inside a
hermetically or partially hermetically sealed package coupled to a
photonic integrated circuit for wavelength multiplexing via a
directly written waveguide, in accordance with the present systems,
devices, and methods.
[0053] FIG. 15 is a left side sectional elevational view of an
optical engine that includes a plurality of laser diodes coupled to
a photonic integrated circuit for wavelength multiplexing via a
directly written waveguide, wherein the waveguide is formed in a
waveguide medium that also provides a hermetic or partially
hermetic seal for the plurality of laser diodes, in accordance with
the present systems, devices, and methods.
[0054] FIGS. 16A and 16B are isometric views of optical engines
including an insulating cover which prevents undesired electrical
signal transmission from electrical connections, and showing
implementations of optical engines having differing positions for a
laser diode driver circuit in accordance with the present systems,
devices, and methods.
[0055] FIG. 17A is a left side sectional elevational view of an
optical engine that includes a plurality of laser diodes inside a
hermetically sealed package, and further includes a grating
waveguide combiner that inputs light emitted from the plurality of
laser diodes and outputs a superimposed collimated beam, in
accordance with the present systems, devices, and methods.
[0056] FIG. 17B is a front side elevational view of the optical
engine of FIG. 17A, in accordance with the present systems,
devices, and methods.
[0057] FIG. 18 is an isometric view of a laser diode, showing a
fast axis and a slow axis of a light beam generated by the laser
diode, in accordance with the present systems, devices, and
methods.
[0058] FIG. 19A is a left side sectional view of a set of
collimation lenses for collimating a beam of light separately along
different axes.
[0059] FIG. 19B is a top side sectional elevational view of the set
of collimation lenses of FIG. 19A.
[0060] FIGS. 19C and 19D are isometric views of exemplary lens
shapes which could be used as lenses in the implementation of FIGS.
19A and 19B.
[0061] FIG. 20A is a left side sectional view of a set of
collimation lenses for circularizing and collimating a beam of
light.
[0062] FIG. 20B is a top side sectional elevational view of the set
of collimation lenses of FIG. 20A.
[0063] FIGS. 20C and 20D are isometric views of exemplary lens
shapes which could be used as a collimation lens in the
implementation of FIGS. 20A and 20B.
DETAILED DESCRIPTION
[0064] In the following description, certain specific details are
set forth in order to provide a thorough understanding of various
disclosed implementations. However, one skilled in the relevant art
will recognize that implementations may be practiced without one or
more of these specific details, or with other methods, components,
materials, etc. In other instances, well-known structures
associated with computer systems, server computers, and/or
communications networks have not been shown or described in detail
to avoid unnecessarily obscuring descriptions of the
implementations.
[0065] Unless the context requires otherwise, throughout the
specification and claims that follow, the word "comprising" is
synonymous with "including," and is inclusive or open-ended (i.e.,
does not exclude additional, unrecited elements or method
acts).
[0066] Reference throughout this specification to "one
implementation" or "an implementation" means that a particular
feature, structure or characteristic described in connection with
the implementation is included in at least one implementation.
Thus, the appearances of the phrases "in one implementation" or "in
an implementation" in various places throughout this specification
are not necessarily all referring to the same implementation.
Furthermore, the particular features, structures, or
characteristics may be combined in any suitable manner in one or
more implementations.
[0067] As used in this specification and the appended claims, the
singular forms "a," "an," and "the" include plural referents unless
the context clearly dictates otherwise. It should also be noted
that the term "or" is generally employed in its sense including
"and/or" unless the context clearly dictates otherwise.
[0068] The headings and Abstract of the Disclosure provided herein
are for convenience only and do not interpret the scope or meaning
of the implementations.
[0069] One or more implementations of the present disclosure
provide laser-based optical engines, for example, laser-based
optical engines for laser projectors used in wearable heads-up
displays or other applications. Generally, the optical engines
discussed herein integrate a plurality of laser dies or diodes
(e.g., 3 laser diodes, 4 laser diodes) within a single,
hermetically or partially hermetically sealed, encapsulated
package. As discussed further below with reference to FIGS. 6-9, in
at least some implementations, photonic integrated circuits having
input facets (e.g., edge couplers, grating couplers) may be used to
wavelength multiplex beams of light emitted by the plurality of
laser diodes into a coaxially superimposed aggregate beam.
Alternatively, each wavelength of light may be channeled
individually through the photonic integrated circuit. As discussed
below with reference to FIGS. 14-15, in at least some
implementations, the laser diodes are coupled to the photonic
integrated circuit via directly written waveguides. In at least
some implementations, the waveguide medium in which the waveguides
are written may also provide a seal for the laser diodes, thereby
eliminating the need for a separate cap to hermetically or
partially hermetically seal the laser diodes on a base substrate,
for example.
[0070] As discussed below with reference to FIGS. 17A-17B, in at
least some implementations, an optical engine may include a grating
waveguide combiner that inputs light emitted from the plurality of
laser diodes and outputs a superimposed collimated beam, as
discussed further below with reference to FIGS. 17A and 17B. Such
optical engines may have various advantages over existing designs
including, for example, smaller volume, lower weight, better
manufacturability, lower cost, faster modulation speed, etc. The
material used for the optical engines discussed herein may be any
suitable materials, e.g., ceramics with advantageous thermal
properties, etc. As noted above, such features are particularly
advantages in various applications including WHUDs.
[0071] FIG. 1A is a left side, elevational sectional view of an
optical engine 100, which may also be referred to as a "multi-laser
diode module" or an "RGB laser module," in accordance with the
present systems, devices, and methods. FIG. 1B is a front side,
elevational sectional view of the optical engine 100. The optical
engine 100 includes a base substrate 102 having a top surface 104
and a bottom surface 106 opposite the top surface. The base
substrate 102 may be formed from a material that is radio frequency
(RF) compatible and is suitable for hermetic sealing. For example,
the base substrate 102 may be formed from low temperature co-fired
ceramic (LTCC), aluminum nitride (AlN), alumina, aluminum nitride
(AlN), Kovar.RTM., other ceramics with suitable thermal properties,
etc. The term Kovar.RTM. generally refers to iron-nickel-cobalt
alloys having similar thermal expansion coefficients to glass and
ceramics, thus making Kovar.RTM. materials particularly suitable
for forming hermetic seals which remain functional in a wide range
of temperatures.
[0072] The optical engine 100 also includes a plurality of chip
submounts 108a-108d (collectively 108) bonded (e.g., attached) to
the top surface 104 of the base substrate 102. The plurality of
chip submounts 108 are aligned in a row across a width of the
optical engine 100 between the left and right sides thereof. Each
of the plurality of chip submounts 108 includes a laser diode 110,
also referred to as a laser chip or laser die, bonded thereto. In
particular, an infrared chip submount 108a carries an infrared
laser diode 110a, a red chip submount 108b carries a red laser
diode 110b, a green chip submount 108c carries a green laser diode
110c, and a blue chip submount 108d carries a blue laser diode
110d. In operation, the infrared laser diode 110a provides infrared
laser light, the red laser diode 110b provides red laser light, the
green laser diode 110c provides green laser light, and the blue
laser diode 110d provides blue laser light. Each of the laser
diodes 110 may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. Each
of the four laser diode/chip submount pairs may be referred to
collectively as a "laser chip on submount," or a laser CoS 112.
Thus, the optical engine 100 includes an infrared laser CoS 112a, a
red laser CoS 112b, a green laser CoS 112c, and a blue laser CoS
112d. In at least some implementations, one or more of the laser
diodes 110 may be bonded directly to the base substrate 102 without
use of a submount 108. It should be appreciated that although some
implementations discussed herein describe laser diodes as chips or
dies on submounts, other dies or types of devices, e.g., p-side
down devices, may be used as well.
[0073] The optical engine 100 also includes a laser diode driver
circuit 114 bonded to the bottom surface 106 of the base substrate
102. The laser diode driver circuit 114 is operatively coupled to
the plurality of laser diodes 110 via suitable electrical
connections 116 to selectively drive current to the plurality of
laser diodes. In at least some implementations, the laser diode
driver circuit 114 may be positioned relative to the CoSs 112 to
minimize the distance between the laser diode driver circuit 114
and the CoSs 112. Although not shown in FIGS. 1A and 1B, the laser
diode driver circuit 114 may be operatively coupleable to a
controller (e.g., microcontroller, microprocessor, ASIC) which
controls the operation of the laser diode driver circuit 114 to
selectively modulate laser light emitted by the laser diodes 110.
In at least some implementations, the laser diode driver circuit
114 may be bonded to another portion of the base substrate 102,
such as the top surface 104 of the base substrate. In at least some
implementations, the laser diode driver circuitry 114 may be
remotely located and operatively coupled to the laser diodes 110.
In order to not require the use of impedance matched transmission
lines, the size scale may be small compared to a wavelength (e.g.,
lumped element regime), where the electrical characteristics are
described by (lumped) elements like resistance, inductance, and
capacitance.
[0074] Proximate the laser diodes 110 there is positioned an
optical director element 118. Like the chip submounts 108, the
optical director element 118 is bonded to the top surface 104 of
the base substrate 102. In the illustrated example, the optical
director element 118 has a triangular prism shape that includes a
plurality of planar faces. In particular the optical director
element 118 includes an angled front face 118a that extends along
the width of the optical engine 100, a rear face 118b, a bottom
face 118c that is bonded to the top surface 104 of the base
substrate 102, a left face 118d, and a right face 118e opposite the
left face. The optical director element 118 may comprise a mirror
or a prism, for example.
[0075] The optical engine 100 also includes a cap 120 that includes
a vertical sidewall 122 having a lower first end 124 and an upper
second end 126 opposite the first end. A flange 128 may be disposed
around a perimeter of the sidewall 122 adjacent the lower first end
124. Proximate the upper second end 126 of the sidewall 122 there
is a horizontal optical window 130 that forms the "top" of the cap
120. The sidewall 122 and the optical window 130 together define an
interior volume 132 sized and dimensioned to receive the plurality
of chip submounts 108, the plurality of laser diodes 110, and the
optical director element 118. The lower first end 124 and the
flange 128 of the cap 120 are bonded to the base substrate 102 to
provide a hermetic or partially hermetic seal between the interior
volume 132 of the cap and a volume 134 exterior to the cap.
[0076] As shown best in FIG. 1A, the optical director element 118
is positioned and oriented to direct (e.g., reflect) laser light
received from each of the plurality of laser diodes 110 upward (as
shown) toward the optical window 130 of the cap 120, wherein the
laser light exits the interior volume 132.
[0077] The cap 120 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 122 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 130 may comprise an entire
top of the cap 120, or may comprise only a portion thereof. In at
least some implementations, the optical window 130 may be located
on the sidewall 122 rather than positioned as a top of the cap 120,
and the laser diodes 110 and/or the optical director element 118
may be positioned and oriented to direct the laser light from the
laser diodes toward the optical window on the sidewall 122. At
least some implementations may not include optical director element
118 such that laser light from the laser diodes may be output
towards the optical window on the sidewall 122 without the need for
intervening optical elements. In at least some implementations, the
cap 120 may include a plurality of optical windows instead of a
single optical window.
[0078] The optical engine 100 also includes four
collimation/pointing lenses 136a-136d (collectively 136), one for
each of the four laser diodes 110a-110d, respectively, that are
bonded to a top surface 138 of the optical window 130. Each of the
plurality of collimation lenses 136 is positioned and oriented to
receive light from a corresponding one of the laser diodes 110
through the optical window 130. In particular, the collimation lens
136a receives light from the infrared laser diode 110a via the
optical director element 118 and the optical window 130, the
collimation lens 136b receives light from the red laser diode 110b
via the optical director element and the optical window, the
collimation lens 136c receives light from the green laser diode
110c via the optical director element and the optical window, and
the collimation lens 136d receives light from the blue laser diode
110d via the optical director element and the optical window.
[0079] Each of the collimation lenses 136 is operative to receive
laser light from a respective one of the laser diodes 110, and to
generate a single color beam. In particular, the collimation lens
136a receives infrared laser light from the infrared laser diode
110a and produces an infrared laser beam 138a, the collimation lens
136b receives red laser light from the red laser diode 110b and
produces a red laser beam 138b, the collimation lens 136c receives
green laser light from the green laser diode 110c and produces a
green laser beam 138c, and the collimation lens 136d receives blue
laser light from the blue laser diode 110d and produces a blue
laser beam 138d.
[0080] The optical engine 100 may also include, or may be
positioned proximate to, a beam combiner 140 that is positioned and
oriented to combine the light beams 138a-138d received from each of
the collimation lenses 136 into a single aggregate beam 142. As an
example, the beam combiner 140 may include one or more diffractive
optical elements (DOE) and/or refractive/reflective optical
elements that combine the different color beams 138a-138d in order
to achieve coaxial superposition. An example beam combiner is shown
in FIG. 3 and discussed below.
[0081] In at least some implementations, the laser CoSs 112, the
optical director element 118, and/or the collimation lenses 136 may
be positioned differently. As noted above, laser diode driver
circuit 114 may be mounted on the top surface 104 or the bottom
surface 106 of the base substrate 102, depending on the RF design
and other constraints (e.g., package size). In at least some
implementations, the optical engine 100 may not include the optical
director element 118, and the laser light may be directed from the
laser diodes 110 toward the collimation lenses 136 without
requiring an intermediate optical director element. Additionally,
in at least some implementations, one or more of the laser diodes
may be mounted directly on the base substrate 102 without use of a
submount.
[0082] For the sake of a controlled atmosphere inside the interior
volume 132, it may be desirable to have no organic compounds inside
the interior volume 132. In at least some implementations, the
components of the optical engine 100 may be bonded together using
no adhesives. In other implementations, a low amount of adhesives
may be used to bond at least one of the components, which may
reduce cost while providing a relatively low risk of organic
contamination for a determined lifetime (e.g., 2 or more years) of
the optical engine 100. The use of adhesives may result in a
partial hermetic seal, but this partial hermetic seal may be
acceptable in certain applications, as detailed below.
[0083] Generally, "hermetic" refers to a seal which is airtight,
that is, a seal which excludes the passage of air, oxygen, and
other gases. "Hermetic" within the present specification carries
this meaning. Further, "partially hermetic" as used herein refers
to a seal which limits, but does not necessarily completely
prevent, the passage of gases such as air. "Partially hermetic" as
used herein may alternatively be stated as "reduced hermiticity".
In the example above, adhesives may be used to bond components.
Such adhesives may result in a seal being not completely hermetic,
in that some amount of gasses may slowly leak through the adhesive.
However, such a seal can still be considered "partially hermetic"
or as having "reduced hermiticity", because the seal reduces the
flow of gasses therethrough.
[0084] In one example application, even in an environment with only
partial hermiticity, the life of laser diodes 110 and transparency
of optical window 130 may be maintained longer than the life of a
battery of a device, such that partial hermiticity may be
acceptable for the devices. In some cases, even protecting interior
volume 132 from particulate with a dust cover may be sufficient to
maintain laser diodes 110 and transparency of optical window 130
for the intended lifespan of the device. In some cases, laser
diodes 110 and transparency of optical window 130 may last for the
intended lifespan of the device even without a protective cover.
Various bonding processes (e.g., attaching processes) for the
optical engine 100 are discussed below with reference to FIG.
5.
[0085] FIG. 2 is a flow diagram of a method 200 of operating an
optical engine, in accordance with the present systems, devices,
and methods. The method 200 may be implemented using the optical
engine 100 of FIGS. 1A-1B, for example. It should be appreciated
that methods of operating optical engines according to the present
disclosure may include fewer or additional acts than set forth in
the method 200. Further, the acts discussed below may be performed
in an order different than the order presented herein.
[0086] At 202, at least one controller may cause a plurality of
laser diodes of an optical engine to generate laser light. As
discussed above, the plurality of laser diodes may be hermetically
or partially hermetically sealed in an encapsulated package. The
laser diodes may produce light sequentially and/or simultaneously
with each other. At 204, at least one optical director element may
optionally receive the laser light from the laser diodes. The
optical director element may comprise a mirror or a prism, for
example. As discussed above, in at least some implementations the
optical engine may be designed such that laser light exits the
optical engine without use of an optical director element.
[0087] At 206, the at least one optical director element, if
included, may direct the received laser light toward an optical
window of the encapsulated package. For example, the optical
director element may reflect the received laser light toward the
optical window of the encapsulated package. In implementations
without at least one optical director element, the laser light
generated by the plurality of laser diodes may be output directly
toward the optical window of the encapsulated package.
[0088] At 208, a plurality of collimation lenses may collimate the
laser light from the laser diodes that exits the encapsulated
package via the optical window to generate a plurality of
differently colored laser light beams. The collimation lenses may
be positioned inside or outside of the encapsulated package. As an
example, the collimation lenses may be physically coupled to the
optical window of the encapsulated package.
[0089] At 210, a beam combiner may combine the plurality of laser
light beams received from each of the collimation lenses into a
single aggregate beam. The beam combiner may include one or more
diffractive optical elements (DOE) that combine different color
beams in order to achieve coaxial superposition, for example. The
beam combiner may include one or more DOEs and/or one or more
refractive/reflective optical elements. An example beam combiner is
shown in FIG. 3 and discussed below.
[0090] FIG. 3 is a schematic diagram of a wearable heads-up display
(WHUD) 300 with an exemplary laser projector 302, and a transparent
combiner 304 in a field of view of an eye 306 of a user of the
WHUD, in accordance with the present systems, devices, and methods.
The WHUD 300 includes a support structure (not shown), with the
general shape and appearance of an eyeglasses frame, carrying an
eyeglass lens 308 with the transparent combiner 304, and the laser
projector 302.
[0091] The laser projector 302 comprises a controller or processor
310, an optical engine 312 comprising four laser diodes 314a, 314b,
314c, 314d (collectively 314) communicatively coupled to the
processor 310, a beam combiner 316, and a scan mirror 318. The
optical engine 312 may be similar or identical to the optical
engine 100 discussed above with reference to FIGS. 1A and 1B.
Generally, the term "processor" refers to hardware circuitry, and
may include any of microprocessors, microcontrollers, application
specific integrated circuits (ASICs), digital signal processors
(DSPs), programmable gate arrays (PGAs), and/or programmable logic
controllers (PLCs), or any other integrated or non-integrated
circuit.
[0092] During operation of the WHUD 300, the processor 310
modulates light output from the laser diodes 314, which includes a
first red laser diode 314a (R), a second green laser diode 314b
(G), a third blue laser diode 314c (B), and a fourth infrared laser
diode 314d (IR). The first laser diode 314a emits a first (e.g.,
red) light signal 320, the second laser diode 314b emits a second
(e.g., green) light signal 322, the third laser diode 314c emits a
third (e.g., blue) light signal 324, and the fourth laser diode
314d emits a fourth (e.g., infrared) light signal 326. All four of
light signals 320, 322, 324, and 326 enter or impinge on the beam
combiner 316. Beam combiner 316 could for example be based on any
of the beam combiners described in U.S. Provisional Patent
Application Ser. No. 62/438,725, U.S. Non-Provisional patent
application Ser. No. 15/848,265 (U.S. Publication Number
2018/0180885), U.S. Non-Provisional patent application Ser. No.
15/848,388 (U.S. Publication Number 2018/0180886), U.S. Provisional
Patent Application Ser. No. 62/450,218, U.S. Non-Provisional patent
application Ser. No. 15/852,188 (U.S. Publication Number
2018/0210215), U.S. Non-Provisional patent application Ser. No.
15/852,282, (U.S. Publication Number 2018/0210213), and/or U.S.
Non-Provisional patent application Ser. No. 15/852,205 (U.S.
Publication Number 2018/0210216).
[0093] In the illustrated example, the beam combiner 316 includes
optical elements 328, 330, 332, and 334. The first light signal 320
is emitted towards the first optical element 328 and reflected by
the first optical element 328 of the beam combiner 316 towards the
second optical element 330 of the beam combiner 316. The second
light signal 322 is also directed towards the second optical
element 330. The second optical element 330 is formed of a dichroic
material that is transmissive of the red wavelength of the first
light signal 320 and reflective of the green wavelength of the
second light signal 322. Therefore, the second optical element 330
transmits the first light signal 320 and reflects the second light
signal 322. The second optical element 330 combines the first light
signal 320 and the second light signal 322 into a single aggregate
beam (shown as separate beams for illustrative purposes) and routes
the aggregate beam towards the third optical element 332 of the
beam combiner 316.
[0094] The third light signal 324 is also routed towards the third
optical element 332. The third optical element 332 is formed of a
dichroic material that is transmissive of the wavelengths of light
(e.g., red and green) in the aggregate beam comprising the first
light signal 320 and the second light signal 322 and reflective of
the blue wavelength of the third light signal 324. Accordingly, the
third optical element 332 transmits the aggregate beam comprising
the first light signal 320 and the second light signal 322 and
reflects the third light signal 324. In this way, the third optical
element 332 adds the third light signal 324 to the aggregate beam
such that the aggregate beam comprises the light signals 320, 322,
and 324 (shown as separate beams for illustrative purposes) and
routes the aggregate beam towards the fourth optical element 334 in
the beam combiner 316.
[0095] The fourth light signal 326 is also routed towards the
fourth optical element 334. The fourth optical element 334 is
formed of a dichroic material that is transmissive of the visible
wavelengths of light (e.g., red, green, and blue) in the aggregate
beam comprising the first light signal 320, the second light signal
322, and the third light signal 324 and reflective of the infrared
wavelength of the fourth light signal 326. Accordingly, the fourth
optical element 334 transmits the aggregate beam comprising the
first light signal 320, the second light signal 322, and the third
light signal 324 and reflects the fourth light signal 326. In this
way, the fourth optical element 334 adds the fourth light signal
326 to the aggregate beam such that the aggregate beam 336
comprises portions of the light signals 320, 322, 324, and 326. The
fourth optical element 334 routes the aggregate beam 336 towards
the controllable scan mirror 318.
[0096] The scan mirror 318 is controllably orientable and scans
(e.g. raster scans) the beam 336 to the eye 306 of the user of the
WHUD 300. In particular, the controllable scan mirror 318 scans the
laser light onto the transparent combiner 304 carried by the
eyeglass lens 308. The scan mirror 318 may be a single bi-axial
scan mirror or two single-axis scan mirrors may be used to scan the
laser light onto the transparent combiner 304, for example. In at
least some implementations, the transparent combiner 304 may be a
holographic combiner with at least one holographic optical element.
The transparent combiner 304 redirects the laser light towards a
field of view of the eye 306 of the user. The laser light
redirected towards the eye 306 of the user may be collimated by the
transparent combiner 304, wherein the spot at the transparent
combiner 304 is approximately the same size and shape as the spot
at the eye 306 of the user. The laser light may be converged by the
eye 306 to a focal point at the retina of eye 306 and creates an
image that is focused. The visible light may create display content
in the field of view of the user, and the infrared light may
illuminate the eye 306 of the user for the purpose of eye
tracking.
[0097] FIG. 4 is a schematic diagram of a wearable heads-up display
(WHUD) 400 with a laser projector 402 in accordance with the
present systems, devices, and methods. WHUD 400 includes a support
structure 404 with the shape and appearance of a pair of eyeglasses
that in use is worn on the head of the user. The support structure
404 carries multiple components, including eyeglass lens 406, a
transparent combiner 408, the laser projector 402, and a controller
or processor 410. The laser projector 402 may be similar or
identical to the laser projector 302 of FIG. 3. For example, the
laser projector 402 may include an optical engine, such as the
optical engine 100 or the optical engine 312. The laser projector
402 may be communicatively coupled to the controller 410 (e.g.,
microprocessor) which controls the operation of the projector 402,
as discussed above. The controller 410 may include or may be
communicatively coupled to a non-transitory processor-readable
storage medium (e.g., memory circuits such as ROM, RAM, FLASH,
EEPROM, memory registers, magnetic disks, optical disks, other
storage), and the controller may execute data and/or instruction
from the non-transitory processor readable storage medium to
control the operation of the laser projector 402.
[0098] In operation of the WHUD 400, the controller 410 controls
the laser projector 402 to emit laser light. As discussed above
with reference to FIG. 3, the laser projector 402 generates and
directs an aggregate beam (e.g., aggregate beam 336 of FIG. 3)
toward the transparent combiner 408 via at least one controllable
mirror (not shown in FIG. 4). The aggregate beam is directed
towards a field of view of an eye of a user by the transparent
combiner 408. The transparent combiner 408 may collimate the
aggregate beam such that the spot of the laser light incident on
the eye of the user is at least approximately the same size and
shape as the spot at transparent combiner 408. The transparent
combiner 408 may be a holographic combiner that includes at least
one holographic optical element.
[0099] FIG. 5 is a flow diagram of a method 500 of manufacturing an
optical engine, in accordance with the present systems, devices,
and methods. The method 500 may be implemented to manufacture the
optical engine 100 of FIGS. 1A-1B or the optical engine 312 of FIG.
3, for example. It should be appreciated that methods of
manufacturing optical engines according to the present disclosure
may include fewer or additional acts than set forth in the method
500. Further, the acts discussed below may be performed in an order
different than the order presented herein.
[0100] At 502, a plurality of laser diodes may be bonded to a
respective plurality of submounts. In at least some
implementations, this method may be performed by an entity
different than that manufacturing the optical engine. For example,
in at least some implementations, one or more of the plurality of
laser diodes (e.g., green laser diode, blue laser diode) may be
purchased as already assembled laser CoSs. For ease of handling and
simplification of the overall process, in at least some
implementations it may be advantageous to also bond laser diodes
that cannot be procured on submounts to a submount as well. As a
non-limiting example, in at least some implementations, one or more
of the laser diodes may be bonded to a corresponding submount using
an eutectic gold tin (AuSn) solder process, which is flux-free and
requires heating up top 280.degree. C.
[0101] At 504, the plurality of CoSs may be bonded to a base
substrate. Alternatively, act 502 could be skipped for at least one
or all of the laser diodes, and act 504 could comprise bonding the
at least one or all of the laser diodes directly to the base
substrate. The base substrate may be formed from a material that is
RF compatible and is suitable for hermetic sealing. For example,
the base substrate may be formed from low temperature co-fired
ceramic (LTCC), aluminum nitride (AlN), alumina, aluminum nitride
(AlN), Kovar.RTM., etc. Since several CoSs are bonded next to each
other on the same base substrate, it may be advantageous to either
"step-solder" them sequentially or to use a bonding technique that
does not rely on re-melting of solder materials. For
step-soldering, each subsequent soldering step utilizes a process
temperature that is less than the process temperatures of previous
solder steps to prevent re-melting of solder materials. It may also
be important that the laser diode-to-submount bonding does not
re-melt during bonding of the CoSs to the base substrate. Bonding
technologies other than step-soldering that may be used include
parallel soldering of all CoS in reflow oven process, thermosonic
or thermocompression bonding, transient liquid phase (TLP) bonding,
laser soldering, etc. Some of these example bonding technologies
are discussed below.
[0102] For parallel soldering of all CoSs in a reflow oven process,
appropriate tooling is required to assure proper bonding and
alignment during the process. An advantage of this process is the
parallel and hence time efficient bonding of all CoSs at once and
even many assemblies in parallel. A possible disadvantage of this
process is the potential loss of the alignment of components during
the reflow process. Generally, a soldering cycle ideally needs a
few minutes of dwell time. Preheating may be used to reduce the
soldering time, which requires a few minutes for such a process
depending on the thermal mass of the components being bonded. Thus,
a batch process may be used with regular soldering to reduce the
assembly costs with high throughput at the expense of alignment
tolerance.
[0103] For thermosonic or thermocompression bonding, thick gold
metallization may be used but no extra solder layer is required.
The temperatures for thermocompression bonding might be as high as
300 to 350.degree. C. to have a good bond with a good thermal
conductivity. Thermosonic bonding may be used to reduce the
pressure and temperature needed for bonding, which may be required
for at least some components that might not tolerate the
temperatures required for thermocompression bonding.
[0104] Transient liquid phase (TLP) bonding may also be used. There
are many different reaction couples that may be used, including
gold-tin, copper-tin, etc. With this method, a liquid phase is
formed during the bonding which will solidify at the same
temperature. The re-melting temperatures of the bond are much
higher than the soldering temperatures.
[0105] In at least some implementations, laser soldering may be
used to bond some or all of the components of the optical engine.
Generally, the thermal characteristic of the parts to be bonded may
be important when implementing a laser soldering process.
[0106] Subsequent reflows of solder are not recommended due to
liquid phase reaction or dissolution mechanisms which may reduce
the reliability of the joint. This could result in voiding at the
interface or a reduction in strength of the joint itself. In order
to mitigate potential reflow dissolution problems, other options
can be taken into consideration, which do not rely on extreme
heating of the device and can be favorable in terms of production
cost. For example, bonding of the base substrate with adhesives
(electrically conductive for common mass, or non-conductive for
floating) may be acceptable with respect to heat transfer and
out-gassing as discussed regarding partial hermetic sealing
above.
[0107] Further, in at least some implementations, a reactive
multi-layer foil material (e.g., NanoFoil.RTM.) or a similar
material may be used as a solder pre-form, which enables localized
heat transfer. A reactive multi-layer foil material is a metallic
material based on a plurality (e.g., hundreds, thousands) of
reactive foils (aluminum and nickel) that enables die-attach
soldering (e.g., silicon chip onto stainless steel part). In such
implementations, dedicated heat transfer support metallizations may
be deposited onto the two components being joined together. This
method may be more advantageous for CoS-to-base substrate mounting
compared to chip-to-submount bonding. Generally, bonding using
reactive multi-layer foil materials enables furnace-free,
low-temperature soldering of transparent or non-transparent
components, without reaching the bonding temperatures for solder
reflow processes. Reactive multi-layer foil materials can be
patterned with a ps-laser into exact preform shapes.
[0108] At 506, the optical director element, if included, may be
bonded to the base substrate proximate the laser CoSs. The optical
director element may be bonded to the base substrate using any
suitable bonding process, including the bonding processes discussed
above with reference to act 504.
[0109] At 508, the laser diode driver circuit may optionally be
bonded to the base substrate. As noted above, the laser diode
driver circuit may be bonded to the base substrate such that the
distance between the laser diode driver circuit and the laser CoSs
is minimized. This may also comprise positioning a plurality of
electrical connections which operatively couple the laser diode
driver circuit to the plurality of laser diodes as shown in FIGS.
16A and 16B. In alternative implementations, the laser diode driver
circuit may be bonded to a separate base substrate from the other
components mentioned above as shown in FIGS. 16B. The process used
to bond the laser diode driver circuit to the base substrate may be
any suitable bonding process, such as bonding processes commonly
used to bond surface mount devices (SMD) to circuit boards. In
other alternative implementations, the laser diode driver circuit
may be mounted directly to a frame of a WHUD. For implementations
where the laser diode drive circuit is not bonded to the same base
substrate as the other components mentioned above, a plurality of
electrical contacts and electrical connections could be bonded to
the base substrate, each electrical connection operatively
connecting a respective electrical contact to a respective laser
diode. Subsequently, the at least one laser driver circuit could be
operatively coupled to the electrical contacts, which will then
electrically couple the laser diode drive circuit to the electrical
connections and consequently to the laser diodes. Exemplary
arrangements of electrical connections and electrical contacts is
discussed later with reference to FIG. 16B.
[0110] At 510, the cap may optionally be bonded to the base
substrate to form a hermetic or partially hermetic seal as
discussed above between the interior volume of the encapsulated
package and an exterior environment. As noted above, it may be
desirable to maintain a specific atmosphere for the laser diode
chips for reliability reasons. In at least some implementations,
adhesive sealing may be undesirable because of the high
permeability of gases. This is especially the case for blue laser
diodes, which emit blue laser light that may bake contamination on
facets and windows, thereby reducing transparency of the optical
window. However, as detailed above regarding FIGS. 1A and 1B,
partial hermiticity, a particulate dust cover, or even no
protective cover may be acceptable for certain applications. In
implementations where the cap would be bonded over electrical
connections which connect the at least one laser diode driver
circuit to the plurality of laser diodes, such as when the at least
one laser diode driver circuit is bonded to the same side of a base
substrate as the laser diodes, or when the at least one laser diode
driver circuit is coupled to electrical contacts bonded to the same
side of the base substrate as the laser diodes, an electrically
insulating cover can first be bonded to the base substrate over the
electrical connections. Subsequently, the cap can be bonded at
least partially to the electrically insulating cover, and
potentially to a portion of the base substrate if the insulating
cover does not fully encircle the intended interior volume. In this
way, at least a portion of the cap will be bonded to the base
substrate indirectly by being bonded to the electrically insulating
cover. In some implementations, the entire cap could be bonded to
the base substrate indirectly by being bonded to an electrically
insulating cover which encircles the intended interior volume.
Exemplary electrically insulating covers are discussed later with
reference to FIGS. 16A and 16B.
[0111] During the sealing process, the atmosphere may be defined by
flooding the package accordingly. For example, the interior volume
of the encapsulated package may be flooded with an oxygen enriched
atmosphere that burns off contaminants which tend to form on
interfaces where the laser beam is present. The sealing itself may
also be performed so as to prevent the exchange between the package
atmosphere and the environment. Due to limitations concerning the
allowed sealing temperature, e.g., the components inside the
package should not be influenced, in at least some implementations
seam welding or laser assisted soldering/diffusion bonding may be
used. In at least some implementations, localized sealing using a
combination of seam welding and laser soldering may be used.
[0112] At 512, the collimation lenses may be actively aligned. For
example, once the laser diode driver circuit has been bonded and
the cap has been sealed, the laser diodes can be turned on and the
collimations lenses for each laser diode can be actively aligned.
In at least some implementations, each of the collimation lenses
may be positioned to optimize spot as well as pointing for each of
the respective laser diodes.
[0113] At 514, the beam combiner may be positioned to receive and
combine individual laser beams into an aggregate beam. As discussed
above, the beam combiner may include one or more diffractive
optical elements and/or one or more refractive/reflective optical
elements that function to combine the different color beams into an
aggregate beam. The aggregate beam may be provided to other
components or modules, such as a scan mirror of a laser projector,
etc.
[0114] FIG. 6 is a top plan view of a photonic integrated circuit
600 for wavelength multiplexing followed by a common collimation
lens 602 and an optional diffractive optical element 604. The
photonic integrated circuit 600 may be a component in an optical
engine, such as an optical engine 700 of FIG. 7, an optical engine
as shown in FIG. 12A, or an optical engine as shown in FIG. 12B
discussed further below. The photonic integrated circuit 600
includes a plurality of input facets 612a-612d and at least one
output facet 608 (e.g., output optical coupler or grating output
coupler). In FIG. 6, input facets 612a-612d are shown as grating
couplers (also referred to as "diffractive grating couplers" or
"grating input couplers") on a top surface 606 thereof, but other
input facets are possible such as illustrated in FIG. 12B discussed
below. In operation, the photonic integrated circuit 600 receives a
plurality of beams of light 610a-610d that are coupled to the
photonic integrated circuit via the input facets 612a-612d,
respectively, and wavelength multiplexes the plurality of beams to
provide a coaxially superimposed aggregate beam of light 614 that
exits the photonic integrated circuit at the output facet 608, such
as an output optical coupler or grating output coupler. Compared to
edge coupling, in at least some applications using grating input
couplers for input facets 612a-612d may allow for relaxed
tolerances for beam alignment. Generally, the photonic integrated
circuit 600 may include one or more diffractive optical elements
(DOE) and/or refractive/reflective optical elements that combine
the different color beams 610a-610d in order to achieve coaxial
superposition.
[0115] Following out-coupling of the aggregate beam 614 from the
output facet 608 of the photonic integrated circuit 600, the
aggregated beam is collimated via the common collimation lens 602.
In at least some implementations, the collimation lens 602 may be
either an achromatic lens or an apochromatic lens (or lens
assemblies), depending on the particular optical design and
tolerances of the system. In at least some implementations, one or
more diffractive optical elements 604 may be used to provide
wavelength dependent focus correction.
[0116] FIG. 7 is a left side sectional elevational view of the
optical engine 700. The optical engine 700 includes several
components that may be similar or identical to the components of
the optical engine 100 of FIGS. 1A and 1B. Thus, some or all of the
discussion above may be applicable to the optical engine 700.
[0117] The optical engine 700 includes a base substrate 702 having
a top surface 704 and a bottom surface 706 opposite the top
surface. The base substrate 702 may be formed from a material that
is radio frequency (RF) compatible and is suitable for hermetic
sealing. For example, the base substrate 702 may be formed from low
temperature co-fired ceramic (LTCC), aluminum nitride (AlN),
alumina, aluminum nitride (AlN), Kovar.RTM., etc.
[0118] The optical engine 700 also includes a plurality of chip
submounts 708 (only one chip submount visible in the sectional view
of FIG. 7) that are bonded (e.g., attached) to the top surface 704
of the base substrate 702. The plurality of chip submounts 708 are
aligned in a row across a width of the optical engine 700 between
the left and right sides thereof. Each of the plurality of chip
submounts 708 includes a laser diode 710, also referred to as a
laser chip or laser die, bonded thereto. In particular, an infrared
chip submount carries an infrared laser diode, a red chip submount
carries a red laser diode, a green chip submount carries a green
laser diode, and a blue chip submount carries a blue laser diode.
In operation, the infrared laser diode provides infrared laser
light, the red laser diode provides red laser light, the green
laser diode provides green laser light, and the blue laser diode
provides blue laser light. Each of the laser diodes 710 may
comprise one of an edge emitter laser or a vertical-cavity
surface-emitting laser (VCSEL), for example. Each of the four laser
diode/chip submount pairs may be referred to collectively as a
"laser chip on submount," or a laser CoS 712. Thus, the optical
engine 700 includes an infrared laser CoS, a red laser CoS, a green
laser CoS, and a blue laser CoS. In at least some implementations,
one or more of the laser diodes 710 may be bonded directly to the
base substrate 702 without use of a submount 708.
[0119] The optical engine 700 also includes a laser diode driver
circuit 714 bonded to the bottom surface 706 of the base substrate
702. The laser diode driver circuit 714 is operatively coupled to
the plurality of laser diodes 710 via suitable electrical
connections 716 to selectively drive current to the plurality of
laser diodes. Generally, the laser diode driver circuit 714 may be
positioned relative to the CoSs 712 to minimize the distance
between the laser diode driver circuit 714 and the CoSs 712.
Although not shown in FIG. 7, the laser diode driver circuit 714
may be operatively coupleable to a controller (e.g.,
microcontroller, microprocessor, ASIC) that controls the operation
of the laser diode driver circuit 714 to selectively modulate laser
light emitted by the laser diodes 710. In at least some
implementations, the laser diode driver circuit 714 may be bonded
to another portion of the base substrate 702, such as the top
surface 704 of the base substrate, similar to the implementations
shown in FIG. 16A. In at least some implementations, the laser
diode driver circuitry 714 may be remotely located and operatively
coupled to the laser diodes 710. In order to not require the use of
impedance matched transmission lines, the size scale may be small
compared to a wavelength (e.g., lumped element regime), where the
electrical characteristics are described by (lumped) elements like
resistance, inductance, and capacitance.
[0120] Proximate the laser diodes 710 there is positioned an
optical director element 718. Like the chip submounts 708, the
optical director element 718 is bonded to the top surface 704 of
the base substrate 702. In the illustrated example, the optical
director element 718 has a triangular prism shape that includes a
plurality of planar faces. In particular the optical director
element 718 includes an angled front face 718a that extends along
the width of the optical engine 700, a rear face 718b, a bottom
face 718c that is bonded to the top surface 704 of the base
substrate 702, a left face 718d, and a right face 718e opposite the
left face. The optical director element 718 may comprise a mirror
or a prism, for example. In at least some implementations, the
angled front face 718a may be curved to provide fast axis
collimation of the laser light from the laser diodes 710.
[0121] The optical engine 700 also includes a cap 720 that includes
a vertical sidewall 722 having a lower first end 724 and an upper
second end 726 opposite the first end. A flange 728 may be disposed
around a perimeter of the sidewall 722 adjacent the lower first end
724. Proximate the upper second end 726 there of the sidewall 722
there is a horizontal (as shown) optical window 730 that forms the
"top" of the cap 120. The sidewall 722 and the optical window 730,
along with a portion of the top surface 704 of the base substrate
702, together define an interior volume 732 sized and dimensioned
to receive the plurality of chip submounts 708, the plurality of
laser diodes 710, and the optical director element 717. The lower
first end 724 and the flange 728 of the cap 720 are bonded to the
base substrate 702 to provide a hermetic or partially hermetic seal
between the interior volume 732 of the cap and a volume 734
exterior to the cap.
[0122] The optical director element 718 is positioned and oriented
to direct (e.g., reflect) laser light received from each of the
plurality of laser diodes 710 upward (as shown) toward the optical
window 730 of the cap 720, wherein the laser light exits the
interior volume 732.
[0123] The cap 720 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 722 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 730 may comprise an entire
top of the cap 720, or may comprise only a portion thereof. In at
least some implementations, the optical window 730 may be located
on the sidewall 722 rather than positioned as a top of the cap 720,
and the laser diodes 710 and/or the optical director element 718
(if present) may be positioned and oriented to direct the laser
light from the laser diodes toward the optical window on the
sidewall 722. In at least some implementations, the cap 720 may
include a plurality of optical windows instead of a single optical
window 730.
[0124] In at least some implementations, the optical engine 700
optionally includes four collimation lenses 736 (only one visible
in the sectional view of FIG. 7), one for each of the four laser
diodes 710. In other implementations, the collimation lenses 736
are omitted. In the illustrated implementation, the collimation
lenses 736 are bonded to a bottom surface of the optical window 730
in a row, although the collimation lenses may be positioned
differently in other implementations. For example, in at least some
implementations, the collimation lenses 736 may be positioned
outside of the package (e.g., outside of the interior volume 732)
rather than inside the package as shown in FIG. 7. Each of the
plurality of collimation lenses 736 may be positioned and oriented
to receive light from a corresponding one of the laser diodes 710,
and to direct collimated light upward (as shown) through the
optical window 730 toward the photonic integrated circuit 600,
which is shown "inverted" in FIG. 7 (relative to FIG. 6) so that
the input facets 612a-612d (collectively, 612) on the surface 606
of the photonic integrated circuit face a top surface 738 of the
optical window 730 of the cap 720.
[0125] The optical director element 718 and the collimation lenses
736 (when present) direct the beams of light 610a-610d (see FIG. 6)
into the photonic integrated circuit 600 via the input facets
612a-612d. The photonic integrated circuit 600 may be bonded to the
top surface of the optical window 730, as shown in FIG. 7. In at
least some implementations, the photonic integrated circuit 600 may
be bonded to the top surface 704 of the base substrate 702 instead.
As discussed above, in operation, the photonic integrated circuit
600 receives a plurality of beams of light 610a-610d via the input
facets 612a-612d (e.g. grating couplers), respectively, and
wavelength multiplexes the plurality of beams to provide a
coaxially superimposed aggregate beam of light 614 that exits the
photonic integrated circuit at the output optical coupler 608.
[0126] In at least some implementations, the laser diodes 710 may
be directly coupled to the photonic integrated circuit 600. In such
implementations, the laser diodes 710 may be positioned immediately
adjacent to a waveguide structure (e.g., photonic integrated
circuit or other waveguide structure) such that sufficient coupling
(e.g., acceptable insertion loss) is achieved. For example, in at
least some implementations, the photonic integrated circuit 600 may
function as the optical window of the package itself.
[0127] Following out-coupling of the aggregate beam 614 from the
output facet 608 of the photonic integrated circuit 600, the
aggregated beam may be collimated via the common collimation lens
602. In at least some implementations, the common collimation lens
602 may be bonded to the top surface 704 proximate the photonic
integrated circuit 600. In at least some implementations, the
collimation lens 602 may be either an achromatic lens or an
apochromatic lens, depending on the particular optical design and
tolerances of the system. In at least some implementations, the
optical engine 700 may include one or more diffractive optical
elements 604 to provide wavelength dependent focus correction.
[0128] In at least some implementations, at least some of the
components may be positioned differently. As noted above, the laser
diode driver circuit 714 may be mounted on the top surface 704 or
the bottom surface 706 of the base substrate 702, or may be
positioned remotely therefrom, depending on the RF design and other
constraints (e.g., package size), similarly to as discussed with
reference to FIGS. 16A and 16B below. In at least some
implementations, the optical engine 700 may not include an optical
director element (e.g., optical director element 718 of FIG. 7),
and the laser light may be directed from the laser diodes 710
toward the optical window 730 directly, with our without
collimation lenses 736. Additionally, in at least some
implementations, one or more of the laser diodes 710 may be mounted
directly on the base substrate 702 without use of a submount.
Further, in at least some implementations, in the case of an
inorganic or acceptably organic waveguide (e.g., photonic
integrated circuit), coupling may be accomplished inside the
encapsulated package. Such feature eliminates the requirement for a
separate window, as the waveguide services as the window (e.g.,
optical window 730). In such implementations, the plurality of
grating couplers of the photonic integrated circuit may be
positioned inside the interior volume of the encapsulated package
and the at least one optical output coupler of the photonic
integrated circuit may be positioned outside of the interior
volume, for example.
[0129] For the sake of a controlled atmosphere inside the interior
volume 732, it may be desirable to have no organic compounds inside
the interior volume 732. In at least some implementations, the
components of the optical engine 700 may be bonded together using
no adhesives. In other implementations, a low amount of adhesives
may be used to bond at least one of the components, which may
reduce cost while providing a relatively low risk of organic
contamination for a determined lifetime (e.g., 2 or more years) of
the optical engine 700. Similarly to as detailed above regarding
FIGS. 1A and 1B, partial hermiticity, a particulate dust cover, or
even no protective cover may be acceptable for certain
applications. Various bonding processes (e.g., attaching processes)
for the optical engine 700 are discussed above with reference to
FIG. 5.
[0130] In at least some implementations, the collimation lenses 736
(when present) and the collimation lens 602 may be actively
aligned. In at least some implementations, the CoSs 712, the cap
720 (including optical window 730), and/or the photonic integrated
circuit 600 may be passively aligned. Further, depending on the
particular design, it may be advantageous to utilize a smaller base
substrate 702 and use an additional carrier substrate instead.
[0131] FIG. 8 is a top plan view of a photonic integrated circuit
800 for wavelength multiplexing followed by a common collimation
lens 802 and an optional diffractive optical element 804. The
photonic integrated circuit 800 may be a component in an optical
engine, such as an optical engine 900 of FIG. 9 or an optical
engine of FIG. 13 discussed further below. The photonic integrated
circuit 800 includes at least one input optical edge 806 having at
least one input facet and at least one output optical edge 808
having at least one output facet. In the example of FIG. 8, input
edge 806 includes four input facets 806a, 806b, 806c, and 806d,
whereas output edge 808 includes one output facet 808a. However, it
is within the scope of the present systems, devices, and methods to
include any appropriate number of input facets and output facets.
Similar to the photonic integrated circuit 600 of FIG. 6, in
operation the photonic integrated circuit 800 receives a plurality
of beams of light 810a-810d that are edge coupled to the photonic
integrated circuit at the input optical edge 806, and wavelength
multiplexes the plurality of beams to provide a coaxially
superimposed aggregate beam of light 812 that exits the photonic
integrated circuit at the output optical edge 808 through output
facet 808a. Generally, the photonic integrated circuit 800 may
include one or more diffractive optical elements (DOE) and/or
refractive/reflective optical elements that combine the different
color beams 810a-810d in order to achieve coaxial
superposition.
[0132] Following out-coupling of the aggregate beam 812 from the
output optical edge 808 of the photonic integrated circuit 800, the
aggregated beam is collimated via the common collimation lens 802.
In at least some implementations, the collimation lens 802 may be
either an achromatic lens or an apochromatic lens (or lens
assemblies), depending on the particular optical design and
tolerances of the system. In at least some implementations, one or
more diffractive optical elements 804 may be used to provide
wavelength dependent focus correction.
[0133] FIG. 9 is a left side sectional elevational view of the
optical engine 900. The optical engine 900 includes several
components that may be similar or identical to the components of
the optical engine 100 of FIGS. 1A and 1B. Thus, some or all of the
discussion above may be applicable to the optical engine 900.
[0134] The optical engine 900 includes a base substrate 902 having
a top surface 904 and a bottom surface 906 opposite the top
surface. The base substrate 902 may be formed from a material that
is radio frequency (RF) compatible and is suitable for hermetic
sealing. For example, the base substrate 902 may be formed from low
temperature co-fired ceramic (LTCC), alumina, aluminum nitride
(AlN), Kovar.RTM., etc.
[0135] The optical engine 900 also includes a plurality of chip
submounts 908 (only one chip submount visible in the sectional view
of FIG. 9) that are bonded (e.g., attached) to the top surface 904
of the base substrate 902. The plurality of chip submounts 908 are
aligned in a row across a width of the optical engine 900 between
the left and right sides thereof. Each of the plurality of chip
submounts 908 includes a laser diode 910, also referred to as a
laser chip or laser die, bonded thereto. In particular, an infrared
chip submount carries an infrared laser diode, a red chip submount
carries a red laser diode, a green chip submount carries a green
laser diode, and a blue chip submount carries a blue laser diode.
In operation, the infrared laser diode provides infrared laser
light, the red laser diode provides red laser light, the green
laser diode provides green laser light, and the blue laser diode
provides blue laser light. Each of the laser diodes 910 may
comprise one of an edge emitter laser or a vertical-cavity
surface-emitting laser (VCSEL), for example. Each of the four laser
diode/chip submount pairs may be referred to collectively as a
"laser chip on submount," or a laser CoS 912. Thus, the optical
engine 900 includes an infrared laser CoS, a red laser CoS, a green
laser CoS, and a blue laser CoS. In at least some implementations,
one or more of the laser diodes 910 may be bonded directly to the
base substrate 902 without use of a submount 908.
[0136] The optical engine 900 also includes a laser diode driver
circuit 914 bonded to the bottom surface 906 of the base substrate
902. The laser diode driver circuit 914 is operatively coupled to
the plurality of laser diodes 910 via suitable electrical
connections 916 to selectively drive current to the plurality of
laser diodes. Generally, the laser diode driver circuit 914 may be
positioned relative to the CoSs 912 to minimize the distance
between the laser diode driver circuit 914 and the CoSs 912.
Although not shown in FIG. 9, the laser diode driver circuit 914
may be operatively coupleable to a controller (e.g.,
microcontroller, microprocessor, ASIC) that controls the operation
of the laser diode driver circuit 914 to selectively modulate laser
light emitted by the laser diodes 910. In at least some
implementations, the laser diode driver circuit 914 may be bonded
to another portion of the base substrate 902, such as the top
surface 904 of the base substrate, similar to the implementation
shown in FIG. 16A. In at least some implementations, the laser
diode driver circuitry 914 may be remotely located and operatively
coupled to the laser diodes 910, similar to the implementations
shown in FIG. 16B. In order to not require the use of impedance
matched transmission lines, the size scale may be small compared to
a wavelength (e.g., lumped element regime), where the electrical
characteristics are described by (lumped) elements like resistance,
inductance, and capacitance.
[0137] The optical engine 900 also includes a cap 920 that includes
a vertical sidewall 922 and a horizontal wall or top portion 925.
The vertical sidewall 922 includes a lower first end 924 and an
upper second end 926 opposite the first end. A flange 928 may be
disposed around a perimeter of the sidewall 922 adjacent the lower
first end 924. Within a portion of the vertical sidewall 922 there
is an optical window 930 positioned proximate the laser diodes 910
to pass light therefrom out of the cap 920. In some
implementations, optical window 930 can extend from base substrate
902 to top portion 925, such that one side of cap 920 is formed
entirely by optical window 930. The sidewall 922 and the optical
window 930 together define an interior volume 932 sized and
dimensioned to receive the plurality of chip submounts 908 and the
plurality of laser diodes 910. The lower first end 924 and the
flange 928 of the cap 920 are bonded to the base substrate 902 to
provide a hermetic or partially hermetic seal between the interior
volume 932 of the cap and a volume 934 exterior to the cap.
[0138] The cap 920 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 922 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 930 may comprise an entire
side of the cap 920, or may comprise only a portion thereof. In at
least some implementations, the cap 920 may include a plurality of
optical windows instead of a single optical window 930.
[0139] The optical engine 900 also includes four coupling lenses
936 (only one visible in the sectional view of FIG. 9), one for
each of the four laser diodes 910 that are bonded to the top
surface 904 of the base substrate 902 in a row. Each of the
plurality of coupling lenses 936 is positioned and oriented to
receive light from a corresponding one of the laser diodes 910
through the optical window 930.
[0140] The coupling lenses 936 couple the beams of light 810a-810d
(see FIG. 8) into the photonic integrated circuit 800 via the input
optical edge 806. The photonic integrated circuit 800 may be bonded
to the top surface 904 of the base substrate 902 proximate the row
of coupling lenses 936. As discussed above, in operation, the
photonic integrated circuit 800 receives a plurality of beams of
light 810a-810d at the input optical edge 806, and wavelength
multiplexes the plurality of beams to provide a coaxially
superimposed aggregate beam of light 812 that exits the photonic
integrated circuit at the output optical edge 808.
[0141] In at least some implementations, the laser diodes 910 may
be "butt" coupled to the photonic integrated circuit 800. In such
implementations, the laser diodes 910 may be positioned immediately
adjacent to a waveguide structure (e.g., photonic integrated
circuit or other waveguide structure) such that sufficient coupling
(e.g., acceptable insertion loss) is achieved without the use of a
coupling lens.
[0142] Following out-coupling of the aggregate beam 812 from the
output optical edge 808 of the photonic integrated circuit 800, the
aggregated beam may be collimated via the common collimation lens
802, which may be bonded to the top surface 904 proximate the
photonic integrated circuit 800. In at least some implementations,
the collimation lens 802 may be either an achromatic lens or an
apochromatic lens, depending on the particular optical design and
tolerances of the system. In at least some implementations, the
optical engine 900 may include one or more diffractive optical
elements 804 bonded to the top surface 904 of the base substrate
902 to provide wavelength dependent focus correction.
[0143] In at least some implementations, at least some of the
components may be positioned differently. As noted above, the laser
diode driver circuit 914 may be mounted on the top surface 904 or
the bottom surface 906 of the base substrate 902, or may be
positioned remotely therefrom, depending on the RF design and other
constraints (e.g., package size). In at least some implementations,
the optical engine 900 may include optical director element (e.g.,
optical director element 118 of FIG. 1), and the laser light may be
directed from the laser diodes 910 toward the coupling lenses 936
via an intermediate optical director element. Additionally, in at
least some implementations, one or more of the laser diodes 910 may
be mounted directly on the base substrate 902 without use of a
submount. Further, in at least some implementations, in the case of
an inorganic or acceptably organic waveguide (e.g., photonic
integrated circuit), coupling may be accomplished inside the
encapsulated package. Such feature eliminates the requirement for a
separate window, as the waveguide services as the window (e.g.,
optical window 930). In such implementations, the at least one
optical input edge of the photonic integrated circuit may be
positioned inside the interior volume of the encapsulated package
and the at least one optical output edge of the photonic integrated
circuit may be positioned outside of the interior volume, for
example.
[0144] For the sake of a controlled atmosphere inside the interior
volume 932, it may be desirable to have no organic compounds inside
the interior volume 932. In at least some implementations, the
components of the optical engine 900 may be bonded together using
no adhesives. In other implementations, a low amount of adhesives
may be used to bond at least one of the components, which may
reduce cost while providing a relatively low risk of organic
contamination for a determined lifetime (e.g., 2 or more years) of
the optical engine 900. Similarly to as detailed above regarding
FIGS. 1A and 1B, partial hermiticity, a particulate dust cover, or
even no protective cover may be acceptable for certain
applications. Various bonding processes (e.g., attaching processes)
for the optical engine 900 are discussed above with reference to
FIG. 5.
[0145] Due to the divergent beam from each of the laser diodes 910
and the lateral distances between the laser diodes, the coupling
lenses 936, and the photonic integrated circuit 800, it may be
advantageous to minimize a distance between the respective output
facets of the laser diodes 910 and the optical window 930. For the
same reason, it may be advantageous to minimize the thickness of
the optical window 930 and the size of the flange 928 of the cap
920 so that the coupling lenses 936 can be positioned relatively
close to the output facets of the laser diodes 910. In at least
some implementations, output window 930 and coupling lenses 936
could be formed as a single element.
[0146] In at least some implementations, the coupling lenses 936
and the collimation lens 802 may be actively aligned. In at least
some implementations, the CoSs 912, the cap 920 (including optical
window 930), and/or the photonic integrated circuit 800 may be
passively aligned. Further, depending on the particular design, it
may be advantageous to utilize a smaller base substrate 902 and use
an additional carrier substrate instead.
[0147] FIG. 10 is a schematic diagram of a laser writing system
1000 in accordance with the present systems, designs and methods.
Laser writing system 1000 comprises at least writing laser 1010,
focusing optic 1012, writeable glass 1020 and translatable mount
1030. Although the term "glass" is used herein for convenience, any
appropriate laser-writable material could be used in place of
writeable glass 1020, such as organically modified ceramics
(ORMOCER), for example. Writing laser 1010 emits laser light 1011.
Laser light 1011 comprises short (femptosecond and/or picosecond
length) pulses of laser light; consequently, laser light 1011 has
extremely high peak instantaneous power. Focusing optic 1012
focuses laser light 1011 to focal point 1013. Writeable glass 1020
may comprise a contiguous piece of glass or similar transparent
material, which is typically transparent to the laser light 1011
emitted by the writing laser 1010; in other words the light emitted
by the writing laser generally will not be absorbed by the glass
via typical (linear) optical processes. At the focal point 1013,
the intensity of laser light 1011 is very high due to the
combination of spatial focusing (focusing the beam of writing laser
light 1011 to a small point 1013) and temporal focusing (emitting
the laser light 1011 as extremely short femptosecond or picosecond
pulses). The high intensity of light at the focal point 1013 allows
nonlinear optical processes such as multiphoton absorption,
avalanche ionization, Coulomb collisions (causing lattice
ionization and breakdown), and heat conduction to occur in the
writeable glass 1020, absorbing the light and changing the
refractive index of the glass. The change in refractive index may
be a positive increase in refractive index.
[0148] Writeable glass 1020 can be physically coupled to
translatable mount 1030, such as by using clamps 1021, adhesive, or
any other appropriate coupling mechanism. Such coupling mechanism
is preferably removable, such that writeable glass 1020 can be
detached from translatable mount 1030 after laser writing is
complete. Translation of translatable mount 1030 in the X, Y,
and/or Z direction will result in corresponding translation of
writeable glass 1020, moving the location of focal point 1013
within writeable glass 1020. Translating the writeable glass 1020
relative to focal point 1013 can create a region of changed
refractive index in the writeable glass 1020. An increased
refractive index in this region causes any light channeled
therethrough to experience total internal reflection, thus forming
waveguide 1022. In other words, waveguide 1022 can be formed as a
continuous path of increased refractive index within writeable
glass 1020 created by laser light 1011 at focal point 1013.
[0149] The technique of FIG. 10 can be used to laser write at least
one waveguide into writeable glass 1020. For example, a photonic
integrated circuit could be written, such as photonic integrated
circuit 600 described with regards to FIG. 6 or photonic integrated
circuit 800 described with regards to FIG. 8. Inputs facets 612a,
612b, 612c, and 612d (such as grating couplers), or input facets
806a, 806b, 806c, and 806d could also be written using this
technique.
[0150] Writing at least one waveguide may include writing an
individual waveguide for each wavelength of light impinging on the
writeable glass 1020, where each waveguide comprises a respective
input facet (such as an input grating coupler) and a respective
output facet. Each output facet may be positioned to provide light
to other components or modules, such as a scan mirror of a laser
projector, etc. In one implementation, four waveguides could be
written into writeable glass 1020, one waveguide for each beam of
light 610a, 610b, 610c, and 610d. Four grating couplers could also
be written, one for each waveguide. In another implementation, four
waveguides could be written into writeable glass 1020, one
waveguide for each beam of light 810a, 810b, 810c, and 810d.
[0151] Writing at least one waveguide may include writing a
waveguide combiner, wherein the waveguide combiner combines
individual laser beams into a coaxially superimposed aggregate
beam. Writing a waveguide combiner may include writing at least
one: directional coupler (DC), Y-branch, whispering gallery mode
coupler, or multi-mode interference coupler. The aggregate beam may
be provided to other components or modules, such as a scan mirror
of a laser projector, etc.
[0152] In other implementations, the photonic integrated circuit
600 or the photonic integrated circuit 800 may include one or more
diffractive optical elements (DOE) and/or refractive/reflective
optical elements that combine the different color beams 610a-d or
810a-d in order to achieve coaxial superposition.
[0153] Alternatively, instead of writing a waveguide combiner,
individual waveguides could be written which do not strictly
coaxially superimpose the beams of light, but instead bring each
beam of light close together. That is, the input facet (e.g.
grating coupler) for each waveguide in the photonic integrated
circuit can be positioned relatively far from the other input
facets, to receive laser light from a respective laser diode, but
the output facets for each of the waveguides can be positioned
relatively close together. In other words, a spacing between the
output facets of each waveguide can be smaller than a spacing of
the input facets of each waveguide. In such an implementation, each
waveguide can be optimized for performance with light of a
corresponding wavelength, for example to ensure that each
wavelength of light exits the photonic integrated circuit with the
same divergence angle as each other wavelength. The output of each
individual waveguide can be placed close enough together (on the
order of 10 s of microns) such that that the light output by each
individual waveguide may still follow the same optical path through
the rest of a projector, display, or WHUD assembly where the
photonic integrated circuit is implemented.
[0154] FIG. 11 is a flow diagram of a method 1100 of manufacturing
an optical engine, in accordance with the present systems, devices,
and methods. The method 1100 may be implemented to manufacture the
optical engine 700 of FIG. 7 or the optical engine 900 of FIG. 9,
for example. It should be appreciated that methods of manufacturing
optical engines according to the present disclosure may include
fewer or additional acts than set forth in the method 1100.
Further, the acts discussed below may be performed in an order
different than the order presented herein.
[0155] Method 1100 can include at least acts 1102, 1104, 1106,
1108, 1110, 1112, 1114, and 1116. Acts 1102, 1104, 1106, 1108, and
1110 substantially correspond to acts 502, 504, 506, 508, and 510,
respectively, of method 500 in FIG. 5, such that the disclosure of
these acts with reference to FIG. 5 is also applicable to FIG. 11.
As such, the details of these acts in FIG. 11 will not be repeated
in the interests of brevity.
[0156] At 1112, a photonic integrated circuit is laser written in
writeable glass, using for example the techniques described with
regards to FIG. 10. The photonic integrated circuit may be similar
to photonic integrated circuit 600 described with reference to FIG.
6 or photonic integrated circuit 800 described with reference to
FIG. 8. Specifically, the photonic integrated circuit can include
at least one input facet and at least one output facet. In
operation, the photonic integrated circuit can receive a plurality
of beams of light that are coupled to the photonic integrated
circuit at a plurality of input facets (e.g. grating couplers), and
wavelength multiplex the plurality of beams of light to provide a
coaxially superimposed aggregate beam of light that exits the
photonic integrated circuit at the output facet. Alternatively, in
operation, the photonic integrated circuit can receive a plurality
of beams of light that are coupled to the photonic integrated
circuit at a plurality of input facets (e.g. grating couplers),
redirect the plurality of beams of light to exit the photonic
integrated circuit at a plurality of spatially close output
facets.
[0157] At 1114, the writeable glass including the photonic
integrated circuit is bonded to the cap or the base substrate. Any
appropriate bonding technique may be used, including those
described with reference to acts 502, 504, 506, 508, and 510 in
FIG. 5. In some implementations, the photonic integrated circuit
may be positioned against an optical window of the cap, such that
laser light from the laser diodes may pass through the optical
window directly into the input facets of the photonic integrated
circuit. Alternatively, the photonic integrated circuit may be
positioned directly against the cap, such that the photonic
integrated circuit acts as the optical window, and laser light from
the laser diodes may directly enter the input facets of the
photonic integrated circuit. In other implementations, the photonic
integrated circuit may be spatially separated from the cap.
[0158] In order for light to travel through a photonic integrated
circuit, the light emitted by each laser diode should preferably be
aligned with a respective input facet of the photonic integrated
circuit with high precision; mis-alignment of greater than 10
micrometers may significantly reduce the efficiency of the photonic
integrated circuit. An output facet of each laser diode may have
dimensions smaller than four square micrometers; aligning such
small components to such high precision presents a non-trivial
technical challenge.
[0159] In one implementation, each input facet of the photonic
integrate circuit could be written as a grating coupler as shown in
FIG. 6, which increases the tolerances for misalignment.
[0160] In act 1116, a collimation lens may be provided such that a
coaxially superimposed beam of light from the output edge of the
photonic integrated circuit will be collimated by the collimation
lens. The collimation lens may optionally optimize the spot (e.g.,
circularize) the coaxially superimposed beam. In some
implementations, more than one collimation lens may be provided if
the light output from the photonic integrated circuit is not a
fully coaxially superimposed beam. The collimation lens or lenses
may be actively aligned after the other components are assembled,
or may be passively aligned such that appropriate alignment is
achieved during assembly.
[0161] As mentioned above, aligning a photonic integrated circuit
such that each input facet of the photonic integrated circuit lines
up with a beam of light emitted by each laser diode with
high-precision presents a non-trivial challenge. The present
systems, devices, and methods provide a solution to this challenge,
by producing photonic integrated circuits where the fabrication
process includes an alignment process, obviating the need for a
later mechanical alignment process, as discussed below with
reference to FIGS. 12, 12B, and 13. Direct laser writing (DLW) as
disclosed herein is a process by which photonic integrated circuits
may be fabricated with high precision that allows for intrinsic
alignment.
[0162] FIG. 12A is a left side sectional view of photonic
integrated circuit writing system 1200a. Photonic integrated
circuit writing system 1200a includes components that may be
substantively similar to components of optical engine 700 and
components of laser writing system 1000. Unless context below
dictates otherwise, the disclosure of components in FIG. 7 and FIG.
10 is applicable to similarly numbered components in FIG. 12A and
will not be repeated in the interests of brevity. Photonic
integrated circuit writing system 1200a includes laser writing
system 1000, which, during operation, writes a photonic integrated
circuit in a block of writeable glass 1020 in a manner similar to
the operation of laser writing system 1000 described above with
reference to FIG. 10. Photonic integrated circuit writing system
1200a can be utilized to manufacture an optical engine using a
process that is similar in at least some respects to method 1100 of
FIG. 11, but with photonic integrated circuit writing system 1200a,
act 1114 can be performed before act 1112, as detailed below.
[0163] Writeable glass 1020 is bonded to cap 720 prior to writing a
photonic integrated circuit therein, using any of the bonding
techniques discussed above. The writeable glass 1020 may comprise a
contiguous piece of glass or similar transparent material that
undergoes a change in refractive index when exposed to
high-intensity laser light. Bonding the writeable glass to the cap
includes positioning and orienting the writeable glass 1020
relative to each laser diode 710 to place the writeable glass 1020
in the path of the beam of light emitted by each laser diode 710,
such that the beam of light emitted by each laser diode 710
impinges on the writeable glass.
[0164] Writeable glass 1020 can be positioned against optical
window 730, such that beams of light from laser diodes 710 pass
through optical window 730 directly into writeable glass 1020.
Alternatively, the writeable glass 1020 may optionally form optical
window 730.
[0165] The entire base substrate 702 and all components bonded
thereto can be physically coupled to translatable mount 1030, such
as with clamps 1021, adhesives, and/or any other appropriate
coupling mechanism. Such coupling mechanism is preferably
removable, such that base substrate 702 and all components bonded
thereto can be detached from translatable mount 1030 after laser
writing of writeable glass 1020 is complete.
[0166] With writeable glass 1020 bonded indirectly to base
substrate 702 via cap 720, and base substrate 702 physically
coupled to translatable mount 1030, at least one waveguide 1022 can
be laser written into writeable glass 1020 by translating base
substrate 702 and all components thereon using translatable mount
1030. At least one input facet 612 (for example at least one
grating input coupler) can also be written into writeable glass
1020 by translating base substrate 702 and all components thereon
using translatable mount 1030. Consequently, writeable glass 1020
becomes a photonic integrated circuit.
[0167] To determine where the at least one waveguide 1022 should be
written, laser diodes 710 could be activated, thus causing beams of
light therefrom to impinge on writeable glass 1020. Writing laser
1010 can be aligned to directly write waveguides and input facets
(e.g. grating couplers as shown in FIG. 12A) at the exact location
where the beams of light from laser diodes 710 impinge on the
writeable glass 1020. In this way, the input facets of the
resulting photonic integrated circuit will be accurately aligned
with the laser diodes, ensuring efficient incoupling of the beams
of light into the photonic integrated circuit.
[0168] Alternatively, the writeable glass 1020 could be
illuminated, such as by being backlit if base substrate 702 is at
least partially transparent. Writing laser 1010 can then be aligned
to directly write waveguides based on locations of shadows caused
by laser diodes 710, CoS's 712 and optical redirector element 718.
In this way, the input facets of the resulting photonic integrated
circuit will be accurately aligned with the laser diodes, ensuring
efficient incoupling of the beams of light into the photonic
integrated circuit.
[0169] Aligning the input facets of the photonic integrated circuit
to the beams of light during the writing stage will be more
accurate than trying to mechanically align a pre-fabricated
photonic integrated circuit, due to deviations that can arise in
the bonding processes of not only the pre-fabricated photonic
integrate circuit, but also the laser diodes. As one example, if
each of four laser diodes is randomly misaligned, it would be
difficult to align a prefabricated photonic integrated circuit to
match the beam of light from each diode, since not only could the
photonic integrated circuit be misaligned during the bonding
processes, but also the spacing between each laser diode may not
match the spacing between each waveguide in the photonic integrated
circuit due to the random misalignment of each of the laser diodes.
Direct laser writing the photonic integrated circuit after all of
the components have been mechanically bonded obviates these issues,
by allowing the position and spacing of each laser diode relative
to the writeable glass to be accounted for after bonding is
complete.
[0170] FIG. 12B is a left side sectional view of photonic
integrated circuit writing system 1200b. Photonic integrated
circuit writing system 1200b includes components that may be
substantively similar to components of photonic integrated circuit
writing system 1200a as discussed with regards to FIG. 12A. Unless
context below dictates otherwise, the disclosure related to
components in FIG. 12A is applicable to similarly numbered
components in FIG. 12B and will not be repeated in the interests of
brevity.
[0171] In FIG. 12B, instead of writing the input facets 612 of the
photonic integrated circuit 600 as grating input couplers, a
reflective surface is instead written to redirect input beams of
light 610 into at least one waveguide 1022 of photonic integrated
circuit 600. For example, the at least one reflective surface could
be a planar region with lower index of refraction than the material
from which writeable glass 1020 is formed. Consequently, laser
light 610 can be redirected by the planar region with lower index
of refraction due to total internal reflection.
[0172] Additionally, FIG. 12B illustrates an implementation in
which at least one laser diode 710 is a vertical-cavity
surface-emitting laser (VCSEL), such that laser light emitted by
the laser diode is directed towards optical window 730 without the
need for an optical redirecting element. Such a laser diode setup
could be implemented in any of the implementations discussed
herein. The implementation of FIG. 12B does not require the use of
a VCSEL, but could instead use a side emitting laser with an
optical redirecting element such as shown in FIGS. 1A and 1B.
[0173] FIG. 13 is a left side sectional view of photonic integrated
circuit writing system 1300. Photonic integrated circuit writing
system 1300 includes components that may be substantively similar
to components of optical engine 900 and components of laser writing
system 1000. Unless context below dictates otherwise, the
disclosure of components in FIG. 9 and FIG. 10 is applicable to
similarly numbered components in FIG. 13 and will not be repeated
in the interests of brevity. Photonic integrated circuit writing
system 1300 includes laser writing system 1000, which, during
operation, writes a photonic integrated circuit in a block of
writeable glass 1020 in a manner similar to the operation of laser
writing system 1000 described above with reference to FIG. 10.
Photonic integrated circuit writing system 1300 can be utilized to
manufacture an optical engine using a process that is similar in at
least some respects to method 1100 of FIG. 11, but with photonic
integrated circuit writing system 1300, act 1114 can be performed
before act 1112, as detailed below.
[0174] Writeable glass 1020 is bonded to base substrate 902 prior
to writing a photonic integrated circuit therein, using any of the
bonding techniques discussed above. The writeable glass 1020 may
comprise a contiguous piece of glass or similar transparent
material that undergoes a change in refractive index when exposed
to high-intensity laser light. Bonding the writeable glass to the
base substrate includes positioning and orienting the writeable
glass 1020 relative to each laser diode 910 to place the writeable
glass 1020 in the path of the beam of light emitted by each laser
diode 910, such that the beam of light emitted by each laser diode
910 impinges on an input edge of the writeable glass.
[0175] Writeable glass 1020 can be butted up against optical window
930, such that beams of light from laser diodes 910 passes through
optical window 930 directly into writeable glass 1020.
Alternatively, the writeable glass 1020 may optionally form optical
window 930. Further, writeable glass 1020 may be bonded directly to
at least one of the laser diodes 910 and/or at least one laser CoS
912.
[0176] The entire base substrate 902 and all components bonded
thereto can be physically coupled to translatable mount 1030, such
as with clamps 1021, adhesives, and/or any other appropriate
coupling mechanism. Such coupling mechanism is preferably
removable, such that base substrate 902 and all components bonded
thereto can be detached from translatable mount 1030 after laser
writing of writeable glass 1020 is complete.
[0177] With writeable glass 1020 bonded to base substrate 902 and
base substrate 902 physically coupled to translatable mount 1030,
at least one waveguide 1022 can be laser written into writeable
glass 1020 by translating base substrate 902 and all components
thereon using translatable mount 1030. Consequently, writeable
glass 1020 becomes a photonic integrated circuit.
[0178] To determine where the at least one waveguide 1022 should be
written, laser diodes 910 could be activated, thus causing beams of
light therefrom to impinge on an input edge of writeable block
1020. Writing laser 1010 can be aligned to directly write
waveguides at the exact location where the beams of light from
laser diodes 910 impinge on the writeable block 1020. In this way,
the input of the resulting photonic integrated circuit will be
accurately aligned with the laser diodes, ensuring efficient
incoupling of the beams of light into the photonic integrated
circuit.
[0179] Alternatively, the writeable glass 1020 could be
illuminated, such as by being backlit if base substrate 902 is at
least partially transparent. Writing laser 1010 can then be aligned
to directly write waveguides at locations where shadows of laser
diodes 910 and/or CoS's 912 appear. In this way, the input of the
resulting photonic integrated circuit will be accurately aligned
with the laser diodes, ensuring efficient incoupling of the beams
of light into the photonic integrated circuit.
[0180] Aligning the input facets of the photonic integrated circuit
to the beams of light during the writing stage will be more
accurate than trying to mechanically align a pre-fabricated
photonic integrated circuit, due to deviations that can arise in
the bonding processes of not only the pre-fabricated photonic
integrate circuit, but also the laser diodes. As one example, if
each of four laser diodes is randomly misaligned, it would be
difficult to align a prefabricated photonic integrated circuit to
match the beam of light from each diode, since not only could the
photonic integrated circuit be misaligned during the bonding
processes, but also the spacing between each laser diode may not
match the spacing between each waveguide in the photonic integrated
circuit due to the random misalignment of each of the laser diodes.
Direct laser writing the photonic integrated circuit after all of
the components have been mechanically bonded obviates these issues,
by allowing the position and spacing of each laser diode relative
to the writeable glass to be accounted for after bonding is
complete.
[0181] In some implementations, a photonic integrated circuit could
be manufactured using a combination of the techniques described
with reference to FIGS. 10, 11, 12A, 12B, and 13 as discussed
below.
[0182] In one example, a large portion of a photonic integrated
circuit could be first written, except for a small portion of the
photonic integrated circuit at the input of writeable glass.
Subsequently, the photonic integrated circuit could be bonded to
the cap or the base substrate such as in FIG. 12A, 12B, or 13, and
the remaining small portion of the photonic integrated circuit at
the input of the writeable glass could be written to couple the
output of each laser diode to the portion of the photonic
integrated circuit which is already written.
[0183] In another example, a first photonic integrated circuit
could be written as in FIG. 10. Subsequently, the first photonic
integrated circuit could be bonded to the cap similar to as in
FIGS. 7, 12A, or 12B, or to the base substrate as in FIG. 9 or 13,
with the first photonic integrated circuit being spatially
separated from the output of each laser diode such that there is a
gap between the output from each laser diode and the first photonic
integrated circuit. In the area in the output path of each laser
diode, a block of writeable glass could be bonded to the cap or to
the base substrate in the gap between the output from each laser
diode and the first photonic integrated circuit. Subsequently, a
second photonic integrated circuit could be written in the
writeable glass similar to in FIGS. 12A, 12B, and 13 to couple the
output of each laser diode to an input edge of the previously
written first photonic integrated circuit. In such an example, the
writeable glass could be formed as the optical window, and/or could
be formed to cover a portion of the first photonic integrated
circuit. FIGS. 14 and 15 illustrate exemplary implementations of
this setup.
[0184] FIG. 14 is a left side sectional elevational view of a
portion of an optical engine 1400. The optical engine 1400 includes
several components that may be similar or identical to the
components of the optical engines 100, 700 or 900. Thus, some or
all of the discussion above may be applicable to the optical engine
1400, and is not repeated herein for the sake of brevity. For
example, portions of the optical engine 1400 not shown in FIG. 14
may be similar or identical to corresponding portions of the
optical engine 900 of FIG. 9.
[0185] The optical engine 1400 includes a base substrate 1402
having a top surface 1404 and a bottom surface (not shown) opposite
the top surface. The base substrate 1402 may be formed from a
material that is radio frequency (RF) compatible and is suitable
for hermetic sealing. For example, the base substrate 1402 may be
formed from low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), alumina, Kovar.RTM., etc.
[0186] The optical engine 1400 also includes a plurality of chip
submounts 1408 (only one chip submount visible in the sectional
view of FIG. 14) that are bonded (e.g., attached) to the top
surface 1404 of the base substrate 1402. The plurality of chip
submounts 1408 are aligned in a row across a width of the optical
engine 1400 between the left and right sides thereof. Each of the
plurality of chip submounts 1408 includes a laser diode 1410, also
referred to as a laser chip or laser die, bonded thereto. In
particular, an infrared chip submount carries an infrared laser
diode, a red chip submount carries a red laser diode, a green chip
submount carries a green laser diode, and a blue chip submount
carries a blue laser diode. In operation, the infrared laser diode
provides infrared laser light, the red laser diode provides red
laser light, the green laser diode provides green laser light, and
the blue laser diode provides blue laser light. Each of the laser
diodes 1410 may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. Each
of the four laser diode/chip submount pairs may be referred to
collectively as a "laser chip on submount," or a laser CoS 1412.
Thus, the optical engine 1400 includes an infrared laser CoS, a red
laser CoS, a green laser CoS, and a blue laser CoS. In at least
some implementations, one or more of the laser diodes 1410 may be
bonded directly to the base substrate 1402 without use of a
submount 1408.
[0187] Although not shown in FIG. 14, the optical engine 1400 also
includes a laser diode driver circuit (e.g., similar or identical
to the laser diode driver circuit 914) bonded to a surface of the
base substrate 1402 or located remotely therefrom. The laser diode
driver circuit 1414 is operatively coupled to the plurality of
laser diodes 1410 via suitable electrical connections 1416 to
selectively drive current to the plurality of laser diodes.
Generally, the laser diode driver circuit 1414 may be positioned
relative to the CoSs 1412 to minimize the distance between the
laser diode driver circuit 1414 and the CoSs 1412. Although not
shown in FIG. 14, the laser diode driver circuit 1414 may be
operatively coupleable to a controller (e.g., microcontroller,
microprocessor, ASIC) that controls the operation of the laser
diode driver circuit 1414 to selectively modulate laser light
emitted by the laser diodes 1410. In at least some implementations,
the laser diode driver circuit 1414 may be bonded to another
portion of the base substrate 1402, such as the top surface 1404 of
the base substrate. In at least some implementations, the laser
diode driver circuitry 1414 may be remotely located and operatively
coupled to the laser diodes 1410. In order to not require the use
of impedance matched transmission lines, the size scale may be
small compared to a wavelength (e.g., lumped element regime), where
the electrical characteristics are described by (lumped) elements
like resistance, inductance, and capacitance. Exemplary placements
for laser diode driver circuitry are described below with reference
to FIGS. 16A and 16B.
[0188] In at least some implementations, the optical engine 1400
also includes a cap 1420 that includes a vertical sidewall 1422 and
a horizontal wall or top portion 1425. The vertical sidewall 1422
includes a lower first end 1424 and an upper second end 1426
opposite the first end. A flange 1428 may be disposed around a
perimeter of the sidewall 1422 adjacent the lower first end 1424.
Within a portion of the vertical sidewall 1422 there is an optical
window 1430 positioned proximate the laser diodes 1410 to pass
light therefrom out of the cap 1420. The sidewall 1422 and the
optical window 1430 together define an interior volume 1432 sized
and dimensioned to receive the plurality of chip submounts 1408 and
the plurality of laser diodes 1410. The lower first end 1424 and
the flange 1428 of the cap 1420 are bonded to the base substrate
1402 to provide a hermetic or partially hermetic seal between the
interior volume 1432 of the cap and a volume 1434 exterior to the
cap.
[0189] The cap 1420 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 1422 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 1430 may comprise an
entire side of the cap 1420, or may comprise only a portion
thereof. In at least some implementations, the cap 1420 may include
a plurality of optical windows instead of a single optical window
1430.
[0190] The optical engine 1400 also includes a waveguide medium or
material 1460 disposed on the top surface 1404 of the base
substrate 1404 between the optical window 1430 of the cap 1420 and
a photonic integrated circuit 1450. The waveguide medium 1460
includes waveguides 1462 (e.g., four waveguides, only one visible
in the sectional view of FIG. 14) that are operative to couple the
plurality of beams of light emitted by the plurality of laser
diodes 1410 from the optical window 1430 of the cap 1420 to input
couplers (e.g., edge couplers, grating couplers) on an edge 1452 or
top surface 1454 of the photonic integrated circuit 1450. Each of
the plurality of waveguides 1462 is positioned and dimensioned to
receive light from a corresponding one of the laser diodes 1410
through the optical window 1430. The waveguides 1462 may be
directly written using the direct laser writing process described
above with reference to FIGS. 10, 11, 12A, 12B, or 13, or any other
suitable process.
[0191] The waveguides 1462 couple the beams of light into the
photonic integrated circuit 1450 via input optical edge couplers or
grating couplers. The photonic integrated circuit 1450 may be
bonded to the top surface 1404 of the base substrate 1402 proximate
the waveguide medium 1460. As discussed above, in operation, the
photonic integrated circuit 1450 receives a plurality of beams of
light at the input couplers, and wavelength multiplexes the
plurality of beams to provide a coaxially superimposed aggregate
beam of light that exits the photonic integrated circuit at an
output optical edge.
[0192] In at least some implementations, at least some of the
components may be positioned differently. As noted above, a laser
diode driver circuit operatively coupled to the laser diodes 1410
may be mounted on the top surface 1404 or the bottom surface of the
base substrate 1402, or may be positioned remotely therefrom,
depending on the RF design and other constraints (e.g., package
size). In at least some implementations, the optical engine 1400
may include optical director element (e.g., optical director
element 118 of FIG. 1), and the laser light may be directed from
the laser diodes 1410 toward the waveguide medium 1460 via an
intermediate optical director element. In at least some
implementations, photonic integrated circuit 1450 and waveguide
medium 1460 may be positioned on top of cap 1420, and the optical
window 1430 may be in top portion 1425 of cap 1420, with light
beams from laser diodes 1410 passing through the optical window
1430 on the top portion of cap 1420 into waveguide medium 1460 and
subsequently photonic integrated circuit 1450. Additionally, in at
least some implementations, one or more of the laser diodes 1410
may be mounted directly on the base substrate 1402 without use of a
submount. Further, in at least some implementations, in the case of
an inorganic or acceptably organic waveguide, coupling may be
accomplished inside the encapsulated package. Such feature
eliminates the requirement for a separate window, as the waveguide
medium 1460 services as the window (e.g., optical window 1430). In
such implementations, the at least one optical input coupler of the
photonic integrated circuit may be positioned inside the interior
volume of the encapsulated package and the at least one optical
output edge of the photonic integrated circuit may be positioned
outside of the interior volume, for example.
[0193] In at least some implementations, the waveguides 1462 may be
directly written into the waveguide medium 1460 using any suitable
direct writing process, such as that described above with reference
to FIGS. 10, 12A, 12B, and 13. The waveguide medium 1460 may
comprise any suitable photosenstive material. In at least some
implementations, the waveguide medium comprises organically
modified ceramic (ORMOCER) material, for example. As noted above,
coupling to the photonic integrated circuit 1450 may be done either
via edge coupling or grating coupling.
[0194] In the illustrated implementation, the written waveguide
1462 and medium 1460 is spaced apart from the optical window 1430,
and a lens shaped surface 1464 is formed in the medium 1460. The
lens shaped surface 1464 may be sized, dimensioned and oriented to
couple beams of light from the laser diodes 1410 into the
waveguides 1462 of the waveguide medium 1460. In other
implementations, the waveguide 1462 and or waveguide medium 1460
may be positioned adjacent (e.g., in contact with) at least one of
the optical window 1430 of the cap 1430 or the photonic integrated
circuit 1450.
[0195] FIG. 15 shows a left side sectional elevational view of a
portion of an optical engine 1500. The optical engine 1500 includes
several components that may be similar or identical to the
components of the optical engines 100, 700, 900, or 1400. Thus,
some or all of the discussion above may be applicable to the
optical engine 1500, and is not repeated herein for the sake of
brevity. For example, portions of the optical engine 1500 not shown
in FIG. 15 may be similar or identical to corresponding portions of
the optical engine 900 of FIG. 9.
[0196] The optical engine 1500 includes a base substrate 1502
having a top surface 1504 and a bottom surface (not shown) opposite
the top surface. The base substrate 1502 may be formed from a
material that is radio frequency (RF) compatible and is suitable
for hermetic sealing. For example, the base substrate 1502 may be
formed from low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), alumina, Kovar.RTM., etc.
[0197] The optical engine 1500 also includes a plurality of chip
submounts 1508 (only one chip submount visible in the sectional
view of FIG. 15) that are bonded (e.g., attached) to the top
surface 1504 of the base substrate 1502. The plurality of chip
submounts 1508 are aligned in a row across a width of the optical
engine 1500 between the left and right sides thereof. Each of the
plurality of chip submounts 1508 includes a laser diode 1510, also
referred to as a laser chip or laser die, bonded thereto. In
particular, an infrared chip submount carries an infrared laser
diode, a red chip submount carries a red laser diode, a green chip
submount carries a green laser diode, and a blue chip submount
carries a blue laser diode. In operation, the infrared laser diode
provides infrared laser light, the red laser diode provides red
laser light, the green laser diode provides green laser light, and
the blue laser diode provides blue laser light. Each of the laser
diodes 1510 may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. Each
of the four laser diode/chip submount pairs may be referred to
collectively as a "laser chip on submount," or a laser CoS 1512.
Thus, the optical engine 1500 includes an infrared laser CoS, a red
laser CoS, a green laser CoS, and a blue laser CoS. In at least
some implementations, one or more of the laser diodes 1510 may be
bonded directly to the base substrate 1502 without use of a
submount 1508.
[0198] Although not shown in FIG. 15, the optical engine 1500 also
includes a laser diode driver circuit (e.g., similar or identical
to the laser diode driver circuit 914) bonded to a surface of the
base substrate 1502 or located remotely therefrom, similarly to as
described with regards to FIGS. 16A and 16B below. The laser diode
driver circuit 1514 is operatively coupled to the plurality of
laser diodes 1510 via suitable electrical connections 1516 to
selectively drive current to the plurality of laser diodes.
[0199] The optical engine 1500 also includes a photonic integrated
circuit 1550 bonded to the top surface 1504 of the base substrate
1502 proximate facets 1511 of the laser diodes 1510. In operation,
the photonic integrated circuit 1550 receives a plurality of beams
of light at input couplers (e.g., edge couplers, grating couplers),
and wavelength multiplexes the plurality of beams to provide a
coaxially superimposed aggregate beam of light that exits the
photonic integrated circuit at an output optical edge (not shown in
FIG. 15).
[0200] In the illustrated implementation, the laser CoSs 1512 and
electrical connections 1516 (e.g., wirebonds) are covered with a
waveguide and sealing medium 1560, which may also cover at least a
portion of an edge 1552 and a top surface 1554 of the photonic
integrated circuit 1550. Advantageously, the waveguide and sealing
medium acts as a sealing material for the laser CoSs 1512,
eliminating the need for a separate cap (e.g., cap 1420 of FIG. 14)
to provide a hermetically or partially hermetically sealed
package.
[0201] The waveguide medium 1560 includes directly written
waveguides 1562 (e.g., four waveguides, only one visible in the
sectional view of FIG. 15) that are operative to couple the
plurality of beams of light emitted at the facets 1511 of the
plurality of laser diodes 1510 to input couplers (e.g., edge
couplers, grating couplers) on the edge 1552 or top surface 1554 of
the photonic integrated circuit 1550. Each of the plurality of
waveguides 1562 is positioned and dimensioned to receive light from
a corresponding one of the laser diodes 1510. The waveguides 1562
may be directly written using any suitable process, such as direct
laser writing as described with reference to FIGS. 10, 12A, 12B,
and 13 above.
[0202] The waveguides 1562 couple the beams of light into the
photonic integrated circuit 1550 via an input optical edge couplers
or grating couplers. The photonic integrated circuit 1550 may be
bonded to the top surface 1504 of the base substrate 1502 proximate
the waveguide medium 1560. As discussed above, in operation, the
photonic integrated circuit 1550 receives a plurality of beams of
light at the input couplers, and wavelength multiplexes the
plurality of beams to provide a coaxially superimposed aggregate
beam of light that exits the photonic integrated circuit at an
output optical edge.
[0203] In at least some implementations, photonic integrated
circuit 1550 may be positioned above laser diodes 1510, and
waveguide and sealing medium 1560 may be formed to cover laser
diodes 1510 and photonic integrated circuit 1550. At least one
waveguide 1562 can be directly written in waveguide medium 1560 to
couple beams of light emitted by laser diodes 1510 to input
couplers on photonic integrated circuit 1550, using for example the
techniques discussed above regarding FIGS. 10, 12A, 12B, and
13.
[0204] Although several different materials may be used for direct
waveguide writing, in at least some implementations, an ORMOCER
material may be used which is tailored to the particular needs
concerning writing as well as transmission wavelengths.
[0205] FIGS. 16A and 16B are isometric views showing
implementations of optical engines having differing positions for a
laser diode driver circuit. The implementations shown in FIGS. 16A
and 16B are similar in at least some respects to the
implementations of FIGS. 1A, 1B, 7, 9, 12A, 12B, 13, 14, and 15,
and one skilled in the art will appreciate that the description
regarding FIGS. 1A, 1B, 7, 9, 12A, 12B, 13, 14, and 15 are
applicable to the implementations of FIGS. 16A and 16B unless
context clearly dictates otherwise.
[0206] FIG. 16A shows an optical engine 1600a which includes a base
substrate 1602. The base substrate 1602 may be formed from a
material that is radio frequency (RF) compatible and is suitable
for hermetic sealing. For example, the base substrate 1602 may be
formed from low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), alumina, Kovar.RTM., etc.
[0207] The optical engine 1600a also includes a plurality of laser
diodes aligned in a row across a width of the optical engine 1600a,
including an infrared laser diode 1610a, a red laser diode 1610b, a
green laser diode 1610c, and a blue laser diode 1610d. In
operation, the infrared laser diode 1610a provides infrared laser
light, the red laser diode 1610b provides red laser light, the
green laser diode 1610c provides green laser light, and the blue
laser diode 1610d provides blue laser light. Each of the laser
diodes may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. In
FIG. 16A, laser diodes 1610a, 1610b, 1610c, and 1610d are shown as
being bonded (e.g., attached) directly to base substrate 1602, as
described above with regards to act 504 in FIG. 5, but one skilled
in the art will appreciate that laser diodes 1610a, 1610b, 1610c,
and 1610d could each be mounted on a respective submount, similar
to as in FIGS. 1A and 1B.
[0208] The optical engine 1600a also includes a laser diode driver
circuit 1614 which can be bonded to the same surface of base
substrate 1602 as the laser diodes 1610a, 1610b, 1610c, 1610d. In
alternative implementations, laser diode driver circuit 1614 can be
bonded to a separate base substrate, such as in FIG. 16B discussed
later. The laser diode driver circuit 1614 is operatively coupled
to the plurality of laser diodes 1610a, 1610b, 1610c, and 1610d via
respective electrical connections 1616a, 1616b, 1616c, 1616d to
selectively drive current to the plurality of laser diodes. In at
least some implementations, the laser diode driver circuit 1614 may
be positioned relative to the laser diodes 1610a, 1610b, 1610c, and
1610d to minimize the distance between the laser diode driver
circuit 1614 and the laser diodes. Although not shown in FIG. 16A,
the laser diode driver circuit 1614 may be operatively coupleable
to a controller (e.g., microcontroller, microprocessor, ASIC) which
controls the operation of the laser diode driver circuit 1614 to
selectively modulate laser light emitted by the laser diodes 1610a,
1610b, 1610c, and 1610d. In at least some implementations, the
laser diode driver circuit 1614 may be bonded to another portion of
the base substrate 1602, such as the bottom surface of the base
substrate 1602. In at least some implementations, the laser diode
driver circuitry 1614 may be remotely located and operatively
coupled to the laser diodes 1610a, 1610b, 1610c, and 1610d. In
order to not require the use of impedance matched transmission
lines, the size scale may be small compared to a wavelength (e.g.,
lumped element regime), where the electrical characteristics are
described by (lumped) elements like resistance, inductance, and
capacitance.
[0209] Proximate the laser diodes 1610a, 1610b, 1610c, and 1610d
there is optionally positioned an optical director element 1618.
Like the laser diodes 1610a, 1610b, 1610c, and 1610d, the optical
director element 1618 is bonded to the top surface of the base
substrate 1602. The optical director element 1618 may be bonded
proximate to or adjacent each of the laser diodes 1610a, 1610b,
1610c, and 1610d. In the illustrated example, the optical director
element 1618 has a triangular prism shape that includes a plurality
of planar faces, similar to optical director element 168 in FIGS.
1A and 1B. The optical director element 1618 may comprise a mirror
or a prism, for example.
[0210] The optical engine 1600a also includes a cap 1620 similar to
cap 120 in FIGS. 1A and 1B or cap 920 in FIG. 9. For clarity, cap
1620 is shown as being transparent in FIG. 16A, though this is not
necessarily the case, and cap 1620 can be at least partially formed
of an opaque material. In the illustrated implementation, cap 1620
can include a horizontal optical window 1630 that forms the "top"
of the cap 1620. Although optical window 1630 in FIG. 16A is shown
as comprising the entire top of cap 1620, in alternative
implementations optical window could comprise only a portion of the
top of cap 1620. Cap 1620 including optical window 1630 defines an
interior volume sized and dimensioned to receive the plurality of
laser diodes 1610a, 1610b, 1610c, 1610d, and the optical director
element 1618. Cap 1620 is bonded to the base substrate 1602 to
provide a hermetic or partially hermetic seal between the interior
volume of the cap 1620 and a volume exterior to the cap 1620. The
optical director element 1618 is positioned and oriented to direct
(e.g., reflect) laser light received from each of the plurality of
laser diodes 1610a, 1610b, 1610c, and 1610d upward toward the
optical window 1630 of the cap 1620, wherein the laser light exits
the interior volume, similar to FIGS. 1A and 1B.
[0211] The cap 1620 may have a round shape, rectangular shape, or
other shape, similarly to as described regarding FIGS. 1A and 1B
above. The optical window 1630 may comprise an entire top of the
cap 1620, or may comprise only a portion thereof. In alternative
implementations, optical window 1630 could be positioned on a side
of cap 1620 to allow beams of light from laser diodes 1610a, 1610b,
1610c, and 1610d to exit the cap through a side portion thereof. In
such an implementation, each of laser diodes 1610a, 1610b, 1610c,
and 1610d can be a side-emitting laser, and optical engine 1600a
may not include optical redirector element 1618.
[0212] In at least some implementations, the cap 1620 may include a
plurality of optical windows instead of a single optical
window.
[0213] The optical engine 1600a can also include four
collimation/pointing lenses similarly to as discussed regarding
FIGS. 1A and 1B above. Each of the collimation lenses can be
operative to receive laser light from a respective one of the laser
diodes 1610a, 1610b, 1610c, or 1610d, and to generate a single
color beam.
[0214] The optical engine 1600a may also include, or may be
positioned proximate to, a beam combiner that is positioned and
oriented to combine the light beams received from each of the
collimation lenses or laser diodes 1610a, 1610b, 1610c, or 1610d
into a single aggregate beam. As an example, the beam combiner may
include one or more diffractive optical elements (DOE) and/or one
or more refractive/reflective optical elements that combine the
different color beams in order to achieve coaxial superposition.
Exemplary beam combiners are shown and discussed with reference to
FIGS. 3, 7, 9, 12A, 12B, or 13.
[0215] In at least some implementations, the laser diodes 1610a,
1610b, 1610c, 1610d, the optical director element 1618, and/or the
collimation lenses may be positioned differently. As noted above,
laser diode driver circuit 1614 may be mounted on a top surface or
a bottom surface of the base substrate 1602, depending on the RF
design and other constraints (e.g., package size). In at least some
implementations, the optical engine 1600a may not include the
optical director element 1618, and the laser light may be directed
from the laser diodes 1610a, 1610b, 1610c, and 1610d toward
collimation lenses without requiring an intermediate optical
director element. Additionally, in at least some implementations,
one or more of the laser diodes may be mounted indirectly on the
base substrate 1602 with a submount.
[0216] Optical engine 1600a in FIG. 16A also includes an
electrically insulating cover 1640. In FIG. 16A, laser diodes
1610a, 1610b, 1610c, and 1610d are each connected to laser diode
driver circuitry 1614 by a respective electrical connection 1616a,
1616b, 1616c, or 1616d positioned as described above with regards
to act 508 in FIG. 5. Electrical connections 1616a, 1616b, 1616c,
and 1616d run across a surface of the base substrate 1602. As
described above with regards to act 510 in FIG. 5, electrically
insulating cover 1640 is placed, adhered, formed, or otherwise
positioned over electrical connections 1616a, 1616b, 1616c, and
1616d, such that each of the electrical connections 1616a, 1616b,
1616c, and 1616d run through electrically insulating cover 1640.
Also as described above with regards to act 510 in FIG. 5, cap 1620
is placed, adhered, formed, or otherwise positioned over
electrically insulating cover 1640, such that cap 1620 does not
contact any of the electrical connections 1616a, 1616b, 1616c, or
1616d. For clarity, cap 1620 is shown as being transparent in FIG.
16A, though this is not necessarily the case, and cap 1620 can be
at least partially formed of an opaque material. Electrically
insulating cover 1640 can be formed of a material with low
electrical permittivity such as a ceramic, such that electrical
signals which run through electrical connections 1616a, 1616b,
1616c, and 1616d do not run into or through electrically insulating
cover 1640. In this way, electrical signals which run through
electrical connections 1616a, 1616b, 1616c, and 1616d can be
prevented from running into or through cap 1620, which can be
formed of an electrically conductive material. Although FIG. 16A
shows electrically insulating cover 1640 as extending along only
part of a side of cap 1620, one skilled in the art will appreciate
that electrically insulating cover 1640 can extend along an entire
side length of cap 1620.
[0217] One skilled in the art will appreciate that the positions of
laser diode driver circuitry 1614, electrical connections 1616a,
1616b, 1616c, 1616d, and electrically insulating cover 1640 as
shown in FIG. 16A could also be applied in other implementations of
the subject systems, devices and methods. For example, in the
implementations of FIGS. 1A and 1B, laser diode driver circuitry
114 could be positioned on top surface 104 of base substrate 102,
and electrical connections 116 could run across top surface 104
under an electrically insulating cover, such that electrical
connections 116 do not contact any conductive portion of cap
120.
[0218] FIG. 16B is an isometric view an optical engine 1600b
similar in at least some respects to optical engine 1600a of FIG.
16A. One skilled in the art will appreciate that the description of
optical engine 1600a in FIG. 16A is applicable to optical engine
1600b in FIG. 16B, unless context clearly dictates otherwise. The
optical engine 1600b includes a base substrate 1603a. Similar to
base substrate 1602 in FIG. 16A, base substrate 1603a may be formed
from a material that is radio frequency (RF) compatible and is
suitable for hermetic sealing. For example, the base substrate
1603a may be formed from low temperature co-fired ceramic (LTCC),
alumina, Kovar.RTM., etc.
[0219] One difference between optical engine 1600b in FIG. 16B and
optical engine 1600a in FIG. 16A relates to what components are
bonded (e.g. attached) to base substrate 1603a. In optical engine
1600b, each of: laser diodes 1610a, 1610b, 1610c, 1610d; cap 1620;
electrical connections 1616a, 1616b, 1616c, 1616d; and electrically
insulating cover 1640 are bonded (e.g., attached) to base substrate
1603a. However, laser diode driver circuit 1614 is not necessarily
bonded directly to base substrate 1603a. Instead, laser diode
driver circuit 1614 could be bonded to a separate base substrate
1603b. Similar to base substrate 1602 in FIG. 16A and base
substrate 1603a in FIG. 16B, base substrate 1603b may be formed
from a material that is radio frequency (RF) compatible and is
suitable for hermetic sealing. For example, the base substrate
1603b may be formed from low temperature co-fired ceramic (LTCC),
alumina, Kovar.RTM., etc. In an alternative implementation, laser
diode drive circuit 1614 may not need to be bonded to a substrate
at all, and could simply be mounted directly to a frame of a
WHUD.
[0220] For implementations where laser diode drive circuit 1614 is
not bonded to base substrate 1603a, electrical contacts 1617a,
1617b, 1617c, and 1617d could be bonded to base substrate 1603a,
each at an end of a respective electrical connection 1616a, 1616b,
1616c, or 1616d as described above with regards to act 508 in FIG.
5. In this way, electrical contacts 1617a, 1617b, 1617c, and 1617d
could be used to electrically couple laser diode drive circuit 1614
to electrical connections 1616a, 1616b, 1616c, and 1616d and
consequently laser diodes 1610a, 1610b, 1610c, and 1610d.
[0221] Although the implementations of FIGS. 16A and 16B illustrate
examples which include cap 1620, cap 1620 could be replaced by a
waveguide and sealing medium similar to as described with reference
to FIG. 15.
[0222] For example, a waveguide and sealing medium could be
disposed on base substrate 1602 in FIG. 16A to cover the plurality
of laser diodes 1610a, 1610b, 1610c, and 1610d; optical director
element 1618 (if included); and at least a portion or all of
electrical connections 1616a, 1616b, 1616c, and 1616d. Laser diode
driver circuitry 1614 could optionally be covered as well, or left
uncovered. In this way, electrical connections 1616a, 1616b, 1616c,
and 1616d will connect laser diode circuitry 1614 to laser diodes
1610a, 1610b, 1610c, and 1610d through the waveguide and sealing
medium.
[0223] As another example, a waveguide and sealing medium could be
disposed on base substrate 1603a in FIG. 16B to cover the plurality
of laser diodes 1610a, 1610b, 1610c, and 1610d; optical director
element 1618 (if included); and a portion of electrical connections
1616a, 1616b, 1616c, and 1616d. Electrical contacts 1617a, 1617b,
1617c, and 1617d could be left uncovered, such that laser diode
circuitry 1614 can be coupled thereto. In this way, electrical
connections 1616a, 1616b, 1616c, and 1616d will connect laser diode
circuitry 1614 to laser diodes 1610a, 1610b, 1610c, and 1610d via
electrical contacts 1617a, 1617b, 1617c, and 1617d, through the
waveguide and sealing medium.
[0224] FIG. 17A is a left side sectional elevational view of an
optical engine 1700. FIG. 17B is a front side elevational view of
the optical engine 1700. The optical engine 1700 includes several
components that may be similar or identical to the components of
the optical engines discussed above. Thus, some or all of the
discussion above may be applicable to the optical engine 1700.
[0225] The optical engine 1700 includes a base substrate 1702
having a top surface 1704 and a bottom surface 1706 opposite the
top surface. The base substrate 1702 may be formed from a material
that is radio frequency (RF) compatible and is suitable for
hermetic sealing. For example, the base substrate 1702 may be
formed from low temperature co-fired ceramic (LTCC), aluminum
nitride (AlN), alumina, etc.
[0226] The optical engine 1700 also includes a plurality of chip
submounts 1708 (four chip submounts 1708a-1708d shown in FIG. 17B)
that are bonded (e.g., attached) to the top surface 1704 of the
base substrate 1702. The plurality of chip submounts 1708 are
aligned in a row across a width of the optical engine 1700 between
the left and right sides thereof. Each of the plurality of chip
submounts 1708 includes a laser diode 1710, also referred to as a
laser chip or laser die, bonded thereto. In particular, an infrared
chip submount 1708a carries an infrared laser diode, a red chip
submount 1708b carries a red laser diode, a green chip submount
1708c carries a green laser diode, and a blue chip submount 1708d
carries a blue laser diode. In operation, the infrared laser diode
provides infrared laser light, the red laser diode provides red
laser light, the green laser diode provides green laser light, and
the blue laser diode provides blue laser light. Each of the laser
diodes 1710 may comprise one of an edge emitter laser or a
vertical-cavity surface-emitting laser (VCSEL), for example. Each
of the four laser diode/chip submount pairs may be referred to
collectively as a "laser chip on submount," or a laser CoS 1712.
Thus, the optical engine 1700 includes an infrared laser CoS, a red
laser CoS, a green laser CoS, and a blue laser CoS. In at least
some implementations, one or more of the laser diodes 1710 may be
bonded directly to the base substrate 1702 without use of a
submount 1708.
[0227] The optical engine 1700 also includes a laser diode driver
circuit 1714 bonded to the bottom surface 1706 of the base
substrate 1702. The laser diode driver circuit 1714 is operatively
coupled to the plurality of laser diodes 1710 via suitable
electrical connections 1716 to selectively drive current to the
plurality of laser diodes. Generally, the laser diode driver
circuit 1714 may be positioned relative to the CoSs 1712 to
minimize the distance between the laser diode driver circuit 1714
and the CoSs 1712. Although not shown in FIG. 17, the laser diode
driver circuit 1714 may be operatively coupleable to a controller
(e.g., microcontroller, microprocessor, ASIC) that controls the
operation of the laser diode driver circuit 1714 to selectively
modulate laser light emitted by the laser diodes 1710. In at least
some implementations, the laser diode driver circuit 1714 may be
bonded to another portion of the base substrate 1702, such as the
top surface 1704 of the base substrate, similar to the
implementation shown in FIG. 16A. In at least some implementations,
the laser diode driver circuitry 1714 may be remotely located and
operatively coupled to the laser diodes 1710, similar to the
implementation shown in FIG. 16B. For example, the laser diode
driver circuitry 1714 may be bonded to another substrate separate
from base substrate 1702, or may be mounted directly to a frame or
support structure of a WHUD in which the optical engine 1700 is
implemented. The electrical connections 1616a-1616d, electrical
contacts 1617a-1617d, and electrically insulating cover 1640 of
FIGS. 16A and 16B could also be implemented in optical engine 1700
shown in FIGS. 17A and 17B. In order to not require the use of
impedance matched transmission lines, the size scale may be small
compared to a wavelength (e.g., lumped element regime), where the
electrical characteristics are described by (lumped) elements like
resistance, inductance, and capacitance.
[0228] The optical engine 1700 also includes a cap 1720 that
includes a vertical sidewall 1722 and a horizontal wall or top
portion 1725. The vertical sidewall 1722 includes a lower first end
1724 and an upper second end 1726 opposite the first end. A flange
1728 may be disposed around a perimeter of the sidewall 1722
adjacent the lower first end 1724. Within a portion of the vertical
sidewall 1722 there is an optical window 1730 positioned proximate
the laser diodes 1710 to pass light therefrom out of the cap 1720.
The sidewall 1722 and the optical window 1730 together define an
interior volume 1732 sized and dimensioned to receive the plurality
of chip submounts 1708 and the plurality of laser diodes 1710. The
lower first end 1724 and the flange 1728 of the cap 1720 are bonded
to the base substrate 1702 to provide a hermetic seal between the
interior volume 1732 of the cap and a volume 1734 exterior to the
cap.
[0229] The cap 1720 may have a round shape, rectangular shape, or
other shape. Thus, the vertical sidewall 1722 may comprise a
continuously curved sidewall, a plurality (e.g., four) of adjacent
planar portions, etc. The optical window 1730 may comprise an
entire side of the cap 1720, or may comprise only a portion
thereof. In at least some implementations, the cap 1720 may include
a plurality of optical windows (e.g., four optical windows, one for
each of the laser diodes 1710) instead of a single optical window
1730.
[0230] The optical engine 1700 also includes four
collimation/pointing lenses 1736, one for each of the four laser
diodes 1710 that are bonded to the top surface 1704 of the base
substrate 1702 in a row. Each of the plurality of collimations
lenses 1736 may be positioned and oriented to receive light from a
corresponding one of the laser diodes 1710 and to direct collimated
light through the optical window 1730. In at least some
implementations, the collimation lenses 1736 may comprise one
micro-optic lens array that is passively aligned and bonded inside
the hermetic housing provided by the cap 1720. In at least some
implementations, the collimation lenses 1736 may be positioned
outside of the cap 1720 and may receive light from the laser diodes
1710 via the optical window 1730.
[0231] The collimations lenses 1736 couple the collimated beams of
light toward a diffractive grating waveguide combiner 1750 which
combines the light to provide a superimposed collimated beam 1756
(FIG. 17A). In the illustrated implementation, the grating
waveguide combiner 1750 includes two waveguides 1750a and 1750b
stacked proximate each other (e.g., with or without space
therebetween), but in other implementations a different number
(e.g., four) of waveguides may be used, depending on the particular
design. The waveguides 1750a and 1750b may be bonded to the top
surface 1704 of the base substrate 1702 or otherwise positioned
proximate the optical window 1730 to receive the collimated beams
of light from the collimation lenses 1736.
[0232] In the illustrated implementation, the grating waveguide
combiner 1750 includes four input grating couplers 1752a-1752d
which receive a collimated light beam from the collimation lenses
1736a-1736d, respectively, and an output grating coupler 1754 that
outputs the superimposed collimated beam 1756 (FIG. 17A). As an
example, the waveguide 1750a may include input grating couplers
1752a and 1752b for receiving infrared light and red light,
respectively, and the waveguide 1750b may include input grating
couplers 1752c and 1752d for receiving green light and blue light,
respectively. In this example, the waveguide 1750a may pass or
otherwise direct the red light and green light to the waveguide
1750b.
[0233] The output grating coupler 1754 may be disposed on a surface
of the waveguide 1750b facing away from the optical window 1730 to
output the superimposed collimated light 1756 to another component
(e.g., one or more diffractive optical elements) of the optical
engine 1700 or to a laser projector of which the optical engine is
a part. For example, following out-coupling of the aggregate beam
1756 from the output grating 1754 of the waveguide 1750b, the
aggregated beam may be collimated via a common collimation lens
(e.g., lens 802 of FIGS. 8 and 9). In at least some
implementations, the collimation lens may be either an achromatic
lens or an apochromatic lens (or lens assemblies), depending on the
particular optical design and tolerances of the system. In at least
some implementations, one or more diffractive optical elements
(e.g., diffractive optical elements 804 of FIGS. 8 and 9) may be
used to provide wavelength dependent focus correction or other
functionality.
[0234] Waveguide combiner 1750, input grating couplers 1752a-1752d,
and output grating coupler 1754 can be formed and positioned using
any appropriate method. As one example, waveguide combiner 1750,
input grating couplers 1752a-1752d, and output grating coupler 1754
can be formed using the technique described with reference to FIGS.
10 and 11. In particular, waveguide combiner 1750, input grating
couplers 1752a-1752d, and output grating coupler 1754 could be
written in writeable glass and/or waveguide medium user a laser
writing assembly, and subsequently positioned on base substrate
1702. As another example, writeable glass and/or waveguide medium
could be positioned on base substrate, and waveguide combiner 1750,
input grating couplers 1752a-1752d, and output grating coupler 1754
can subsequently be directly laser written therein, such as by
using similar techniques to those described with reference to FIGS.
12A, 12B, 13, 14 and 15.
[0235] Throughout this application, collimation lenses have been
represented in the Figures by a simple curved lens shape. However,
the subject systems, devices, and methods can utilize more advanced
collimation schemes, as appropriate for a given application.
[0236] FIG. 18 shows an exemplary situation where using an advanced
collimation scheme would be helpful. FIG. 18 is an isometric view
of a laser diode 1800. The laser diode 1800 may be similar or
identical to the various laser diodes discussed herein. The laser
diode 1800 outputs a laser light beam 1802 via an output facet 1804
of the laser diode. FIG. 18 shows the divergence of the light 1802
emitting from the laser diode 1800. As shown, the light beam 1802
may diverge by a substantial amount along a fast axis 1806 (or
perpendicular axis) and by a lesser amount in the slow axis 1808
(parallel axis). As a non-limiting example, in at least some
implementations, the light beam 1802 may diverge with full width
half maximum (FWHM) angles of up to 40 degrees in the fast axis
direction 1806 and up to 10 degrees in the slow axis direction
1808. This divergence results in a rapidly expanding elliptical
cone.
[0237] FIGS. 19A and 19B show an exemplary collimation scheme that
can be used to circularize and collimate an elliptical beam such as
that shown in FIG. 18. FIG. 19A illustrates an orthogonal view of
the fast axis 1806 of light beam 1802 emitted from laser diode
1800. FIG. 19B illustrates an orthogonal view of the slow axis 1808
of light beam 1802 emitted from laser diode 1800. As shown in FIG.
19A, a first lens 1900 collimates light beam 1802 along fast axis
1806. As shown in FIG. 19B, first lens 1900 is shaped so as to not
substantially influence light beam 1802 along slow axis 1808.
Subsequently, as shown in FIG. 19B, light beam 1802 is collimated
along slow axis 1808 by a second lens 1902. As shown in FIG. 19A,
second lens 1902 is shaped so as to not substantially influence
light beam 1802 along fast axis 1806. In essence, light beam 1802
is collimated along fast axis 1806 separately from slow axis 1808.
By collimating light beam 1802 along fast axis 1806 separately from
slow axis 1808, the collimation power applied to each axis can be
independently controlled by controlling the power of lens 1900 and
lens 1902 separately. Further, spacing between each of laser diode
1800, lens 1900, and lens 1902 can be controlled to collimate light
beam 1802 to a certain width in each axis separately. If light beam
1802 is collimated along fast axis 1806 to the same width as slow
axis 1808, light beam 1802 can be circularized. Because light beam
1802 will typically diverge faster in the fast axis 1806, it is
generally preferable to collimate light beam 1802 along fast axis
1806 first, then collimate light beam 1802 along slow axis 1808
after. However, it is possible in certain applications to collimate
light beam 1802 along slow axis 1808 first, and subsequently
collimate light beam 1802 along fast axis 1806 after. This can be
achieved by reversing the order of first lens 1900 with second lens
1902, with respect to the path of travel of light beam 1802.
[0238] FIGS. 19C and 19D are isometric views which illustrate
exemplary shapes for lenses 1900 and 1902. Each of lens 1900 and
1902 can be for example a half-cylinder as in FIG. 19C, a full
cylinder as in FIG. 19D, a quarter cylinder, a three-quarter
cylinder, any other partial cylinder, or any other appropriate
shape. Lenses 1900 and 1902 can be similarly shaped, or can have
different shapes.
[0239] FIGS. 20A and 20B illustrate an alternative collimation
scheme. FIG. 20A illustrates an orthogonal view of the fast axis
1806 of light beam 1802 emitted from laser diode 1800. FIG. 20B
illustrates an orthogonal view of the slow axis 1808 of light beam
1802 emitted from laser diode 1800. As shown in FIG. 20A, a first
lens 2000 redirects light beam 1802 along fast axis 1806, to reduce
divergence of light beam 1802 along fast axis 1806. As shown in
FIG. 20B, first lens 2000 is shaped so as to not substantially
influence light beam 1802 along slow axis 1808. Preferably, first
lens 2000 will reduce divergence of light beam 1802 along fast axis
1806 to match divergence of light beam 1802 along slow axis 1808.
That is, first lens 2000 preferably circularizes light beam 1802.
Subsequently, as shown in FIGS. 20A and 20B, light beam 1802 is
collimated along both fast axis 1806 and slow axis 1808 by a second
lens 2002. As shown in FIGS. 20A and 20B, second lens 2002 is
shaped similarly with respect to both the fast axis 1806 and the
slow axis 1808, to evenly collimate light beam 1802. In essence,
first lens 2000 circularizes light beam 1802, and subsequently
second lens 2002 collimates light beam 1802 along both axes. First
lens 2000 can for example be shaped similarly to lens 1900 or lens
1902 discussed above, and shown in FIGS. 19C and 19D. Second lens
2002 can for example be shaped as a double convex lens as
illustrated in FIG. 20C, or a single convex lens (convex on either
side) as illustrated in FIG. 20D, or any other appropriate shape of
collimating lens.
[0240] The collimation schemes illustrated in FIGS. 19A-19D and
20A-20D, and discussed above could be used in place of any of the
collimation lenses described herein, including at least collimation
lenses 136a, 136b, 136c, 136d.
[0241] A person of skill in the art will appreciate that the
teachings of the present systems, methods, and devices may be
modified and/or applied in additional applications beyond the
specific WHUD implementations described herein. In some
implementations, one or more optical fiber(s) may be used to guide
light signals along some of the paths illustrated herein.
[0242] The WHUDs described herein may include one or more sensor(s)
(e.g., microphone, camera, thermometer, compass, altimeter, and/or
others) for collecting data from the user's environment. For
example, one or more camera(s) may be used to provide feedback to
the processor of the WHUD and influence where on the display(s) any
given image should be displayed.
[0243] The WHUDs described herein may include one or more on-board
power sources (e.g., one or more battery(ies)), a wireless
transceiver for sending/receiving wireless communications, and/or a
tethered connector port for coupling to a computer and/or charging
the one or more on-board power source(s).
[0244] The above description of illustrated embodiments, including
what is described in the Abstract, is not intended to be exhaustive
or to limit the embodiments to the precise forms disclosed.
Although specific embodiments of and examples are described herein
for illustrative purposes, various equivalent modifications can be
made without departing from the spirit and scope of the disclosure,
as will be recognized by those skilled in the relevant art. The
teachings provided herein of the various embodiments can be applied
to other portable and/or wearable electronic devices, not
necessarily the exemplary wearable electronic devices generally
described above.
[0245] For instance, the foregoing detailed description has set
forth various embodiments of the devices and/or processes via the
use of block diagrams, schematics, and examples. Insofar as such
block diagrams, schematics, and examples contain one or more
functions and/or operations, it will be understood by those skilled
in the art that each function and/or operation within such block
diagrams, flowcharts, or examples can be implemented, individually
and/or collectively, by a wide range of hardware, software,
firmware, or virtually any combination thereof. In one embodiment,
the present subject matter may be implemented via Application
Specific Integrated Circuits (ASICs). However, those skilled in the
art will recognize that the embodiments disclosed herein, in whole
or in part, can be equivalently implemented in standard integrated
circuits, as one or more computer programs executed by one or more
computers (e.g., as one or more programs running on one or more
computer systems), as one or more programs executed by on one or
more controllers (e.g., microcontrollers) as one or more programs
executed by one or more processors (e.g., microprocessors, central
processing units, graphical processing units), as firmware, or as
virtually any combination thereof, and that designing the circuitry
and/or writing the code for the software and or firmware would be
well within the skill of one of ordinary skill in the art in light
of the teachings of this disclosure.
[0246] When logic is implemented as software and stored in memory,
logic or information can be stored on any processor-readable medium
for use by or in connection with any processor-related system or
method. In the context of this disclosure, a memory is a
processor-readable medium that is an electronic, magnetic, optical,
or other physical device or means that contains or stores a
computer and/or processor program. Logic and/or the information can
be embodied in any processor-readable medium for use by or in
connection with an instruction execution system, apparatus, or
device, such as a computer-based system, processor-containing
system, or other system that can fetch the instructions from the
instruction execution system, apparatus, or device and execute the
instructions associated with logic and/or information.
[0247] In the context of this specification, a "non-transitory
processor-readable medium" can be any element that can store the
program associated with logic and/or information for use by or in
connection with the instruction execution system, apparatus, and/or
device. The processor-readable medium can be, for example, but is
not limited to, an electronic, magnetic, optical, electromagnetic,
infrared, or semiconductor system, apparatus or device. More
specific examples (a non-exhaustive list) of the computer readable
medium would include the following: a portable computer diskette
(magnetic, compact flash card, secure digital, or the like), a
random access memory (RAM), a read-only memory (ROM), an erasable
programmable read-only memory (EPROM, EEPROM, or Flash memory), a
portable compact disc read-only memory (CDROM), digital tape, and
other non-transitory media.
[0248] The various embodiments described above can be combined to
provide further embodiments. To the extent that they are not
inconsistent with the specific teachings and definitions herein, at
least the following are incorporated herein by reference in their
entirety: U.S. Provisional Patent Application Ser. No. 62/438,725,
U.S. Non-Provisional patent application Ser. No. 15/848,265 (U.S.
Publication Number 2018/0180885), U.S. Non-Provisional patent
application Ser. No. 15/848,388 (U.S. Publication Number
2018/0180886), U.S. Provisional Patent Application Ser. No.
62/450,218, U.S. Non-Provisional patent application Ser. No.
15/852,188 (U.S. Publication Number 2018/0210215), U.S.
Non-Provisional patent application Ser. No. 15/852,282, (U.S.
Publication Number 2018/0210213), U.S. Non-Provisional patent
application Ser. No. 15/852,205 (U.S. Publication Number
2018/0210216), U.S. Provisional Patent Application Ser. No.
62/575,677, U.S. Provisional Patent Application Ser. No.
62/591,550, U.S. Provisional Patent Application Ser. No.
62/597,294, U.S. Provisional Patent Application Ser. No.
62/608,749, U.S. Provisional Patent Application Ser. No.
62/609,870, U.S. Provisional Patent Application Ser. No.
62/591,030, U.S. Provisional Patent Application Ser. No.
62/620,600, U.S. Provisional Patent Application Ser. No.
62/576,962, U.S. Provisional Patent Application Ser. No.
62/760,835, U.S. Non-Provisional patent application Ser. No.
16/201,664, U.S. Non-Provisional Patent Application Ser. No.
16/168,690, U.S. Non-Provisional Patent Application Ser. No.
16/171,206, U.S. Non-Provisional patent application Ser. No.
16/203,221, U.S. Non-Provisional patent application Ser. No.
16/216,899, U.S. Non-Provisional patent application Ser. No.
16/231,019, and/or PCT Patent Application PCT/CA2018051344. Aspects
of the embodiments can be modified, if necessary, to employ
systems, circuits and concepts of the various patents, applications
and publications to provide yet further embodiments.
[0249] These and other changes can be made to the embodiments in
light of the above-detailed description. In general, in the
following claims, the terms used should not be construed to limit
the claims to the specific embodiments disclosed in the
specification and the claims, but should be construed to include
all possible embodiments along with the full scope of equivalents
to which such claims are entitled. Accordingly, the claims are not
limited by the disclosure.
* * * * *