U.S. patent application number 11/507784 was filed with the patent office on 2008-02-28 for packaging of frequency-doubled, extended-cavity, surface-emitting laser components on a common substrate.
This patent application is currently assigned to TEXAS INSTRUMENTS INCORPORATED. Invention is credited to Terry A. Bartlett, Bradley M. Haskett, Steven M. Penn.
Application Number | 20080049299 11/507784 |
Document ID | / |
Family ID | 39113129 |
Filed Date | 2008-02-28 |
United States Patent
Application |
20080049299 |
Kind Code |
A1 |
Haskett; Bradley M. ; et
al. |
February 28, 2008 |
PACKAGING OF FREQUENCY-DOUBLED, EXTENDED-CAVITY, SURFACE-EMITTING
LASER COMPONENTS ON A COMMON SUBSTRATE
Abstract
In one embodiment, a laser module comprising an optical element,
a frequency converter, a selective reflector, and one or more
surface-emitters, each coupled to a common substrate, wherein the
emitters, the optical element, the frequency converter, and the
selective reflector are positioned with respect to each other such
that at least a portion of the coherent light emitted from the
surface-emitters travels through the optical element, through the
frequency converter and through the selective reflector. In a
method embodiment, a method for frequency converting light
generated by a surface-emitter, wherein the light passes through an
optical element, a frequency converter, and a selective reflector,
each coupled to a common substrate.
Inventors: |
Haskett; Bradley M.; (Allen,
TX) ; Penn; Steven M.; (Plano, TX) ; Bartlett;
Terry A.; (Dallas, TX) |
Correspondence
Address: |
TEXAS INSTRUMENTS INCORPORATED
P O BOX 655474, M/S 3999
DALLAS
TX
75265
US
|
Assignee: |
TEXAS INSTRUMENTS
INCORPORATED
|
Family ID: |
39113129 |
Appl. No.: |
11/507784 |
Filed: |
August 22, 2006 |
Current U.S.
Class: |
359/326 |
Current CPC
Class: |
H01S 5/423 20130101;
H01S 3/08059 20130101; H01S 3/0815 20130101; H01S 5/02325 20210101;
H01S 3/109 20130101; H01S 5/141 20130101; H01S 5/0071 20130101;
G02F 1/37 20130101 |
Class at
Publication: |
359/326 |
International
Class: |
G02F 1/35 20060101
G02F001/35 |
Claims
1. A laser module comprising: a substrate; at least one prism, a
frequency converter, a selective reflector, and at least one
surface-emitter; each positioned with respect to each other such
that at least a portion of the light emission from the at least one
surface-emitter travels through the at least one prism, through the
frequency converter and through the selective reflector and at
least another portion of the light emission cycles between the
selective reflector and the at least one surface-emitter; and
wherein each of the at least one prism, the frequency converter,
the selective reflector, and the at least one surface-emitter is
coupled to the substrate.
2. A laser module comprising: a substrate; an optical element, a
frequency converter, a selective reflector, and a surface-emitter,
positioned with respect to each other such that at least a portion
of the light emission from the surface-emitter travels through the
optical element, through the frequency converter, and through the
selective reflector; and wherein the optical element, frequency
converter, selective reflector, and surface-emitter are each
coupled to the substrate.
3. The laser module of claim 2, wherein the surface-emitter and the
optical element are positioned such that the optical element
redirects at least a portion of the light emitted from the
surface-emitter.
4. The laser module of claim 2, wherein the surface-emitter and the
optical element are positioned such that the optical element does
not redirect the light emission from the surface-emitter.
5. The laser module of claim 2, wherein the optical element
polarizes at least a portion of the light emission from the
surface-emitter.
6. The laser module of claim 2, wherein the optical element is
capable of beam-splitting the light transmitted from the frequency
converter such that light having a first set of frequencies is
directed in a first direction and light having a second set of
frequencies is directed in a second direction.
7. The laser module of claim 2, wherein the surface-emitter, the
optical element, the frequency converter, and the selective
reflector are further positioned such that at least a portion of
the light emission from the surface-emitter may cycle between
surface-emitter and the selective reflector.
8. The laser module of claim 2, wherein the surface-emitter forms a
part of a vertical external cavity surface-emitting laser.
9. The laser module of claim 2, wherein the frequency converter
comprises crystals capable of harmonic generation.
10. The laser module of claim 2, wherein the selective reflector is
capable of selectively transmitting and reflecting specific
frequencies of light.
11. The laser module of claim 2, wherein the frequency converter is
temperature controlled by components coupled to the substrate and
is substantially thermally isolated from the surface-emitter.
12. The laser module of claim 2, and further comprising a heat sink
coupled to the substrate that controls the temperature of the
surface-emitter.
13. The laser module of claim 2, wherein the optical element
comprises one or more mirrors.
14. The laser module of claim 2, wherein the optical element
comprises one or more prisms.
15. A method for frequency converting light generated by a
surface-emitter comprising: coupling a surface-emitter, an optical
element, a frequency converter, and a selective reflector to a
common substrate; and directing the coherent light emission from
the surface-emitter through the optical element, and through the
frequency converter to the selective reflector.
16. The method of claim 15, wherein the surface-emitter, the
optical element, the frequency converter, and the selective
reflector are positioned such that at least a portion of the light
emission from the surface-emitter may cycle between the
surface-emitter and the selective reflector through the frequency
converter.
17. The method of claim 15, wherein the surface-emitter forms a
part of a vertical external cavity surface-emitting laser.
18. The method of claim 15, wherein the frequency converter
comprises crystals capable of harmonic generation.
19. The method of claim 15, wherein the surface-emitter and the
optical element are positioned such that the optical element
redirects at least a portion of the light emitted from the
surface-emitter.
20. The method of claim 15, wherein the surface-emitter and the
optical element are positioned such that the optical element does
not redirect the light emission from the surface-emitter.
Description
TECHNICAL FIELD OF THE INVENTION
[0001] This invention relates in general to lasers, and, in
particular, to an improved method of packaging the same.
BACKGROUND OF THE INVENTION
[0002] Within the optics industry, numerous applications require a
light source capable of producing multiple Watts of visible light.
For example, DLP.RTM. high definition televisions (HDTV)
incorporate high-power lamps or light-emitting diodes (LED). More
recently, vertical external cavity surface-emitting lasers
(VECSELs) have been developed which, when combined with a
frequency-doubling crystal, form a laser module capable of
producing sufficient visible light to power video displays.
Conventional packaging of the optical components that make up the
laser module is expensive and difficult to manufacture for a
variety of reasons.
SUMMARY
[0003] In one embodiment, a laser module comprising an optical
element, a frequency converter, a selective reflector, and one or
more surface-emitters, each coupled to a common substrate, wherein
the emitters, the optical element, the frequency converter, and the
selective reflector are positioned with respect to each other such
that at least a portion of the light emitted from the
surface-emitters travels through the optical element, through the
frequency converter and through the selective reflector.
[0004] In a method embodiment, a method for frequency converting
light generated by a surface-emitter, wherein the light passes
through an optical element, a frequency converter, and a selective
reflector, each coupled to a common substrate.
[0005] Depending on the specific features implemented, particular
embodiments of the present invention may exhibit some, none, or all
of the following technical advantages. Various embodiments may be
capable of aligning within tight tolerances using precision
semiconductor-type equipment. In addition, various embodiments may
have temperature control components integrated into the common
substrate. Other technical advantages will be readily apparent to
one skilled in the art from the following figures, description and
claims. Moreover, while specific advantages have been enumerated,
various embodiments may include all, some or none of the enumerated
advantages.
BRIEF DESCRIPTION OF THE DRAWINGS
[0006] For a more complete understanding of the present invention,
and for further features and advantages thereof, reference is now
made to the following description taken in conjunction with the
accompanying drawings, in which:
[0007] FIG. 1A is a perspective view illustrating a method of
forming a portion of a laser module;
[0008] FIG. 1B is one example of a cross sectional view
illustrating one embodiment of a portion of a laser module;
[0009] FIG. 2A is a perspective view illustrating a method of
forming a portion of a laser module;
[0010] FIG. 2B is one example of a cross sectional view
illustrating one embodiment of a portion of a laser module;
[0011] FIGS. 3A and 3B are cross sectional views illustrating
alternative examples of a method of forming a portion of a laser
module.
[0012] FIG. 4 is a cross section view of one embodiment of a
portion of laser module 400 comprising a single output.
DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS
[0013] Particular examples specified throughout this document are
intended for example purposes only, and are not intended to limit
the scope of the present disclosure. In particular, this document
is not intended to be limited to a particular application, such as,
video display. Moreover, the illustrations in FIGS. 1A through 4
are not intended to be to scale.
[0014] FIG. 1A is a perspective view of one embodiment of a portion
of a laser module 100. In this example, a laser module 100
comprises a system of components attached to a common substrate 102
and is capable of producing sufficient visible light for display
applications. Substrate 102 may comprise, for example, silicon or a
multi-layer co-fired ceramic header.
[0015] In this particular example, a surface-emitter 104 and
substrate 102 are attached in substantially parallel planes.
Surface-emitter 104 may comprise, for example, a plurality of
vertical-cavity surface-emitters that produce diffraction-limited
Gaussian beams of infrared (IR) light; however, any suitable device
that emits light that may be used directly or indirectly by a light
modulator may be used.
[0016] In this particular example, an optical element 106 is
capable of reflecting, polarizing, and beam-splitting light.
Optical element 106 comprises, in this embodiment, two right
triangle-shaped total internal reflection (TIR) prisms 106a and
106b bonded together and separated by a beam-splitting and
polarizing surface as indicated by reference number 10. A surface
indicated by reference number 120 of prism 106a is attached
substantially parallel to substrate 102 and outwardly from
surface-emitter 104. In this example, prism 106b is disposed
outwardly from prism 106a. Depending on the desired optical output
from laser module 100, other embodiments may not include prism
106b. Although this example uses TIR prisms, other selectively
reflective elements may be used without departing from the scope of
the present disclosure.
[0017] In this example, a frequency converter 108 is attached to
substrate 102. Frequency converter 108 may comprise, for example,
crystals capable of harmonic generation such as, for example,
periodically poled lithium niobate (PPLN) crystals or Lithium
Triborate LiB305 (LBO) crystals.
[0018] In this example, a selective reflector 112 is attached to
substrate 102 and is substantially parallel to surface-emitter 104.
Selective reflector 112 may comprise, for example, one or more
selective mirrors, each mirror transmitting specific frequencies of
visible light while reflecting IR.
[0019] Conventional packaging of the optical components that make
up visible laser modules is expensive and difficult to manufacture
for a variety of reasons. For example, as recognized by the
teachings of the invention, the various conventional optical
components do not have practical mounting surfaces that are on a
common plane, or even mutually parallel planes. This complicates
aligning the components within tight tolerance requirements. In
addition, the laser emitter generates a significant amount of heat
that must be efficiently removed from the module, while the
frequency-doubling crystal must be maintained at a very specific
temperature and therefore must be thermally isolated from the laser
emitter.
[0020] Unlike conventional laser modules described in the
background, surface-emitter 104, optical element 106, and frequency
converter 108 are attached to a common substrate, where they may be
aligned within tight tolerances using precision semiconductor-type
die attach equipment. In addition, selective reflector 112 may be
aligned to the remainder of laser module 100 based on the optical
output from laser module 100. Each component may be held in place
by, for example, solder or a very stable adhesive.
[0021] Unlike conventional laser modules described in the
background, frequency converter 108 and surface-emitter 104 are
attached to a common substrate comprising temperature-controlling
components. For example, frequency converter 108 may be thermally
isolated from surface-emitter 104 by means of an insulative
substrate material, such as alumina for example. In addition,
frequency converter 108 may be heated to a controlled temperature,
as measured by thermistor 110, by a heater 114 integrated into
substrate 102. To remove the heat generated by surface-emitter 104,
a heat sink 116 may be brazed or otherwise attached to substrate
102. Heat sink 116 may comprise, for example, a highly conductive
metal such as copper-tungsten or a thermally conductive ceramic
such as aluminum-nitride.
[0022] FIG. 1B is a cross section view of one embodiment of a
portion of laser module 100. In this example, surface-emitter 104
comprises a plurality of vertical-cavity surface-emitters that
produce diffraction-limited Gaussian beams of infrared (IR) light;
however, any suitable device that emits light that may be used
directly or indirectly by a light modulator may be used.
[0023] In this particular example, the IR output from
surface-emitter 104 is folded 90 degrees and polarized by optical
element 106 as indicated by reference number 122. The IR output
from optical element 106 as indicated by reference number 124
passes through a frequency converter 108, which converts at least a
portion of the IR beam into visible light. Although this example
uses TIR prisms, other reflective elements may be used without
departing from the scope of the present disclosure.
[0024] In this example, selective reflector 112 is capable of
transmitting specific frequencies of visible light converted within
frequency converter 108, while reflecting other frequencies of
light. Laser module 100 outputs the visible light transmitted
through selective reflector 112 as indicated by reference number
126.
[0025] In this example, light reflected from selective reflector
112 returns back through frequency converter 108 as indicated by
reference number 128. As the IR reflected from selective reflector
112 returns through frequency converter 108, at least a portion of
the IR beam converts to visible light.
[0026] In this example, the beam-splitting surface 118 within
optical element 106 reflects a range of visible light 90 degrees,
as indicated by reference number 130, while transmitting other
frequencies, including IR. The reflected visible light folds
another 90 degrees, as indicated by reference number 132, by a
surface of 106b and outputs from laser module 200 in direction
parallel to the light transmitted through selective reflector 112,
as indicated by reference number 134. The transmitted IR folds 90
degrees by a surface of 106a, as indicated by reference number 122,
reflects off surface-emitter 104 and combines with the output from
surface-emitter 104.
[0027] Thus, by packaging the laser module 100 components on a
common substrate each component may be aligned in a single active
alignment using precision equipment. This greatly facilitates the
manufacturability of laser module 100 while possibly shrinking the
package size. Other embodiments may comprise alternative components
or alternative component placements without departing from the
scope of the present disclosure. For example, FIGS. 2A and 2B
illustrate an alternative coupling for surface-emitter 104 and the
corresponding optical components that direct the light path.
However, the embodiment in FIG. 1 may be preferable since it can be
implemented with fewer component alignment steps. FIGS. 3A and 3B
illustrate examples of alternative components that may make up the
optical element 106. FIG. 4 illustrates an example of an
alternative embodiment of a laser module that that produces a
single output.
[0028] FIG. 2A is a perspective view of an alternative embodiment
of a portion of a laser module 200. In this example, laser module
200 comprises a system of components attached to a common substrate
202 and is capable of producing multiple Watts of visible light.
Substrate 202 may comprise, for example, silicon or a multi-layer
co-fired ceramic header.
[0029] In this particular example, surface-emitter 204 is attached
to a surface of a right-angle block 216 disposed outwardly from
substrate 202. Right-angle block 216 and substrate 202 are attached
in substantially parallel planes. Right-angle block 216 may
comprise, for example, a highly conductive metal such as
copper-tungsten or a thermally conductive ceramic such as
aluminum-nitride. Surface-emitter 204 may comprise, for example, a
plurality of vertical-cavity surface-emitters that produce
diffraction-limited Gaussian beams of infrared (IR) light; however,
any suitable device that emits light that may be used directly or
indirectly by a light modulator may be used.
[0030] In this particular example, an optical element 206 is
capable of polarizing and beam-splitting the optical output from
surface-emitter 204. In addition, optical element 206 comprises two
right triangle-shaped total internal reflection (TIR) prisms 206a
and 206b bonded together and separated by a beam-splitting and
polarizing surface, in this example, as indicated by reference
number 218. A surface indicated by reference number 220 of prism
206a is attached substantially parallel to substrate 202 while
another surface of 202a is substantially parallel to
surface-emitter 204. In this example, TIR prism 206b is disposed
outwardly from TIR prism 206a. Depending on the desired optical
output from laser module 200, other embodiments may not include
prism TIR 206b. Although this example uses TIR prisms, other
reflective elements may be used without departing from the scope of
the present disclosure.
[0031] In this example, a frequency converter 208 is attached to
substrate 202. Frequency converter 208 may comprise, for example,
crystals capable of harmonic generation such as, for example,
periodically poled lithium niobate (PPLN) crystals or Lithium
Triborate LiB305 (LBO) crystals.
[0032] In this example, a selective reflector 212 is attached to
substrate 202 and is substantially perpendicular to the
surface-emitter 204 surface; however, other configurations may be
used, involving those in which the reflector is closer to parallel
than perpendicular to the surface-emitter 204 surface. Selective
reflector 212 may comprise, for example, one or more selective
mirrors, each mirror transmitting specific frequencies of visible
light while reflecting IR.
[0033] Unlike conventional laser modules described in the
background, right-angle block 216, optical element 206, and
frequency converter 208 are attached to a common substrate, wherein
they may be aligned within tight tolerances using precision
semiconductor-type die attach equipment. In addition, the selective
reflector 212 may be aligned to the remainder of laser module 200
based on the optical output from laser module 200. Each component
may be held in place by, for example, solder or a very stable
adhesive.
[0034] Unlike conventional laser modules described in the
background, frequency converter 208 and surface-emitter 204 are
attached to a common substrate comprising temperature-controlling
components. For example, frequency converter 208 may be thermally
isolated from surface-emitter 204 by means of an insulative
substrate material, such as alumina for example. In addition,
frequency converter 208 may be heated to a controlled temperature,
as measured by thermistor 210, by a heater 214 integrated into
substrate 202. Right-angle block 216 is capable of removing from
substrate 202 the heat generated by surface-emitter 204.
[0035] FIG. 2B is a cross section view of one embodiment of a
portion of laser module 200. In this example, surface-emitter 204
comprises a plurality of vertical-cavity surface-emitters that
produce diffraction-limited Gaussian beams of infrared (IR) light;
however, any suitable device that emits light that may be used
directly or indirectly by a light modulator may be used.
[0036] In this example, the IR output from surface-emitter 204 is
polarized as it passes through optical element 206 in a direction
substantially parallel to the surface of substrate 202, as
indicated by reference number 230. Depending on the desired optical
output from laser module 200, other embodiments may not include
prism TIR 206b. Although this example uses TIR prisms, other
selectively reflective elements may be used without departing from
the scope of the present disclosure.
[0037] The IR output from optical element 206 passes through a
frequency converter 208, which converts at least a portion of the
IR beam into visible light.
[0038] In this example, selective reflector 212 is capable of
transmitting specific frequencies of visible light converted within
frequency converter 208, while reflecting other frequencies of
light. Laser module 200 outputs the visible light transmitted
through selective reflector 212, as indicated by reference number
226.
[0039] In this example, light reflected from selective reflector
212 returns back through frequency converter 208. As the IR
reflected from selective reflector 212 returns through frequency
converter 208, as indicated by reference number 228, at least a
portion of the IR beam converts to visible light.
[0040] In this example, the beam-splitting surface within optical
element 206, as indicated by reference number 218, reflects a range
of visible light 90 degrees, as indicated by reference numeral 230,
while transmitting other frequencies, including IR. The reflected
visible light folds 90 degrees, as indicated by reference number
232, by a surface of 206b and outputs from laser module 200 in a
direction parallel to the light transmitted through selective
reflector 212, as indicated by reference number 234. The
transmitted IR reflects off surface-emitter 204 and combines with
the output from surface-emitter 204.
[0041] Other embodiments that require only a single output from
laser module 200 may not reflect light within optical element 206.
Such embodiments may comprise an optical element 206 that performs
the function of polarizing without reflecting or redirecting
light.
[0042] FIG. 3A shows an alternative embodiment of a portion of a
laser module 300. Optical element 306 comprises a plurality of
mirrors 306a and 306b disposed outwardly from a substrate 302. In
this example, optical element 306 is capable of reflecting,
polarizing, and beam-splitting light. Mirror 306a and 306b are
positioned at right angles, in this embodiment. A beam-splitting
and polarizing surface of mirror 306b reflects visible light while
transmitting polarized IR. Mirror 306a reflects visible light and
IR. Surface-emitter 304 is attached to substrate 302 inwardly from
optical element 306.
[0043] FIG. 3B shows an alternative embodiment of a portion of a
laser module 300. In this example, optical element 306 is capable
of reflecting, polarizing, and beam-splitting light. Optical
element 306 comprises one or more mirrors 306a attached to one or
more total internal reflection (TIR) prisms 306b disposed outwardly
from a common substrate. In this example, a beam-splitting and
polarizing surface of prism 306b reflects visible light while
transmitting polarized IR. Mirror 306a reflects visible light and
IR. Surface-emitter 304 is attached to a common substrate inwardly
from optical element 306.
[0044] FIG. 4 is a cross section view of one embodiment of a
portion of laser module 400 comprising optical components attached
to a common substrate. In this particular example, laser module 400
generates a single output.
[0045] In this example, surface-emitter 404 comprises a plurality
of vertical-cavity surface-emitters that produce
diffraction-limited Gaussian beams of infrared (IR) light; however,
any suitable device that emits light that may be used directly or
indirectly by a light modulator may be used.
[0046] In this example, the IR output from surface-emitter 404 is
folded 90 degrees, as indicated by reference number 422, and
polarized by optical element 406. Optical element 406 comprises a
total internal reflection (TIR) prism. Although this example uses a
TIR prism, other reflective elements may be used without departing
from the scope of the present disclosure.
[0047] In this example, the IR output from optical element 406
passes through a frequency converter 408, which converts at least a
portion of the IR beam into visible light. In this example,
selective reflector 412 is capable of transmitting specific
frequencies of visible light converted within frequency converter
408, while reflecting other frequencies of light. Laser module 400
outputs the visible light transmitted through selective reflector
412, as indicated by reference number 426.
[0048] In this example, light reflected from selective reflector
412 returns back through frequency converter 408. As the IR
reflected from selective reflector 112 returns through frequency
converter 408, as indicated by reference number 428, at least a
portion of the IR beam converts to visible light.
[0049] In this example, the light returning from frequency
converter 408 folds 90 degrees within optical element 406, as
indicated by reference number 422, reflects off surface-emitter 404
and follows the same path as the output from surface-emitter
404.
[0050] Although the present invention has been described in several
embodiments, a myriad of changes, variations, alterations,
transformations, and modifications may be suggested to one skilled
in the art, and it is intended that the present invention encompass
such changes, variations, alterations, transformations, and
modifications as falling within the spirit and scope of the
appended claims.
* * * * *