U.S. patent application number 12/493855 was filed with the patent office on 2012-09-20 for micro free-space wdm device.
This patent application is currently assigned to Alliance Fiber Optic Products, Inc.. Invention is credited to Daoyi Wang, Frank Wu.
Application Number | 20120237222 12/493855 |
Document ID | / |
Family ID | 43380860 |
Filed Date | 2012-09-20 |
United States Patent
Application |
20120237222 |
Kind Code |
A9 |
Wang; Daoyi ; et
al. |
September 20, 2012 |
Micro Free-Space WDM Device
Abstract
Techniques for designing optical devices that can be
manufactured in volume are disclosed. In an exemplary an optical
assembly, to ensure that all collimators are on one side to
facilitate efficient packaging, all collimators are positioned on
both sides of a substrate. Thus one or more beam folding components
are used to fold a light beam up and down through the collimators
on top of the substrate and bottom of the substrate.
Inventors: |
Wang; Daoyi; (Sunnyvale,
CA) ; Wu; Frank; (Fremont, CA) |
Assignee: |
Alliance Fiber Optic Products,
Inc.
Sunnyvale
CA
|
Prior
Publication: |
|
Document Identifier |
Publication Date |
|
US 20100329678 A1 |
December 30, 2010 |
|
|
Family ID: |
43380860 |
Appl. No.: |
12/493855 |
Filed: |
June 29, 2009 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
11669947 |
Feb 1, 2007 |
7843644 |
|
|
12493855 |
|
|
|
|
Current U.S.
Class: |
398/79 |
Current CPC
Class: |
G02B 6/29367
20130101 |
Class at
Publication: |
398/79 |
International
Class: |
H04J 14/02 20060101
H04J014/02 |
Claims
1. An optical assembly comprising: at least a common collimator; a
substrate; an array of channel collimators including an upper set
of collimators and a lower set of collimators, wherein the upper
set of collimators is mounted on top of the substrate, and the
lower set of collimators is mounted on bottom of the substrate; one
or more beam folding components mounted near an end of the
substrate, wherein the one or more of the beam folding components
turn a light beam traveling through the upper set of collimators to
the lower set of collimators, or a light beam traveling through the
lower set of collimators to the upper set of collimators, wherein
all of the collimators and the common collimator are on one side of
the beam folding components.
2. The optical assembly of claim 1, wherein the one or more beam
folding components are mounted on portions extended from the
substrate.
3. The optical assembly of claim 1, wherein the one or more beam
folding components are mounted on a side wall of the substrate.
4. The optical assembly of claim 1, wherein each of the one or more
beam folding components is cut into two halves, one being mounted
on top of the substrate and the other being mounted on bottom of
the substrate.
5. The optical assembly of claim 4, wherein each of the one or more
beam folding components is slanted to accommodate an arrangement of
the channel collimators and common collimator.
6. The optical assembly of claim 1, wherein the channel collimators
and common collimator are arranged in parallel and boned to the
substrate.
7. The optical assembly of claim 6, wherein a pair of wedges is
used to securely position each of the channel collimators and
common collimator to the substrate.
8. The optical assembly of claim 7, wherein the edges are curved on
one side to accommodate a shape of the each of the channel
collimators and common collimator.
9. The optical assembly of claim 1, where the optical assembly is
enclosed in an enclosure that is shaped in a way to accommodate a
duplicated optical assembly.
10. An optical assembly comprising: at least a common collimator; a
substrate with a certain thickness to form a side surface; an array
of channel collimators including an upper set of collimators and a
lower set of collimators, wherein the upper set of collimators is
mounted on top of the substrate, and the lower set of collimators
is mounted on bottom of the substrate; one or more beam folding
components mounted onto the side surface of the substrate, wherein
the one or more of the beam folding components turn a light beam
traveling through the upper set of collimators to the lower set of
collimators, or a light beam traveling through the lower set of
collimators to the upper set of collimators, wherein all of the
collimators and the common collimator are on one side of the beam
folding components.
11. The optical assembly of claim 10, wherein the channel
collimators and common collimator are arranged in parallel and
boned to the substrate.
12. The optical assembly of claim 11, wherein a pair of wedges is
used to securely position each of the channel collimators and
common collimator to the substrate.
13. The optical assembly of claim 12, wherein the edges are curved
on one side to accommodate a shape of the each of the channel
collimators and common collimator.
14. The optical assembly of claim 10, wherein each of the one or
more beam folding components is a prism.
15. The optical assembly of claim 10, wherein each of the one or
more beam folding components is a pair of mirrors.
Description
CROSS REFERENCE
[0001] This application is related to U.S. patent Ser. No.
11/379,788, commonly assigned, entitled "Optical devices and method
for making the same", now U.S. Pat. No. 7,224,865.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] The invention is generally related to the area of optical
devices. In particular, the present invention is related to optical
wavelength multiplexing/demultiplexer or add/drop devices with new
optical layouts and manufacturing processes.
[0004] 2. The Background of Related Art
[0005] Optical add/drop and multiplexer/demultiplexer devices are
optical components often used in optical systems and networks.
These devices using wavelength division multiplexing (WDM)
techniques allow a simultaneous transfer of optical signals at
different wavelengths or channels through a single optical link
such as an optical fiber. In operation, a WDM device or system may
need to drop or add a set of channels from or to a transmitting
signal. Multiplexer/demultiplexer (Mux/Demux) is often needed for
this application.
[0006] FIG. 1 replicates a WDM device disclosed in U.S. Pat. No.
5,583,683. A multiple wavelength light beam traveling in a fiber is
separated into multiple narrow spectral bands, each directed to an
individual port. At each of the ports for a channel, a dielectric
thin film filter is used to transmit a specified wavelength in the
multi-wavelength (collimated) light passed by the port but reflects
all other wavelengths. The remaining of the multi-wavelength signal
continues to a next channel port, where an in-band signal at a
specific wavelength is transmitted and all others are reflected.
The remaining of the multi-wavelength signal continues to propagate
along an optical path. After multiple bounces, signals at different
wavelengths are separated. Compared with a conventional three-port
cascading modules, the dimension of the device of FIG. 1 is small
in size as fiber routing in the three-port modules are replaced
with collimated beams, thus the routing overhead is saved.
[0007] It is well known that a fiber is not allowed to bend too
small. For example, for the widely used SMF-28e fiber, the minimum
bend radius is about 30 mm. When being routed, the fiber roll
wastes a specific space, for example, 60 mm in diameter for SMF-28e
fiber. Without fiber routing, a WDM device box could be even
smaller than a square of 30 mm by 30 mm.
[0008] Even so, for the prior art device of FIG. 1, the fiber
input/output (I/O) ports are positioned on both sides of a
mechanical box. In the process of fiber handling, due to the
minimum radius limitation, the space waste could be doubled as
shown in FIG. 2A. One of the features, objects and advantages of
the current invention as will be described below is to have all the
I/O ports deposed on one side of a device as shown in FIG. 2B. For
a one-sided device, as the I/O ports are on one side of the device,
thus fiber routing could be eliminated.
[0009] The one-sided optical layout is realized by beam folding
components. Prisms or mirrors are commonly used as beam folding
components as shown in FIGS. 3A-3C. These components are all to be
used and covered by different embodiments of the present
invention.
[0010] FIG. 4 replicates an optical device of U.S. Pat. No.
6,847,450 using turning prisms to bend light beams from adding
channel collimators vertical to the main plane (beam cascading
plane). Compared with the prior art device of FIG. 1, the length of
the device of FIG. 4 is reduced by a collimator length, but it is
at the cost of the height as the cascading optics is now along with
the height dimension of the device of FIG. 4.
[0011] FIG. 5 replicates a device of U.S. Pat. No. 7,068,880 that
is similar to that of FIG. 4. The major difference is that in U.S.
Pat. No. 7,068,880, the beam bending is at the collimator lens
while in U.S. Pat. No. 6,847,450 the bending occurs after
collimators. In either case, the beams are bent by 90 degrees. The
common problem is that the height of the device is now big. As will
be described below, the beams are also turned twice to reduce the
height of a resulting device. Further unlike these prior art
devices, the beam folding occurs along a zigzag optical path,
resulting in the height being smaller, compared with prior art
devices of FIG. 4 and FIG. 5. As will be appreciated from the
disclosure herein, the height of the prior art devices is the width
of the zigzagging optics (typically >5 mm) plus two collimator
mounting space while the height of a device designed in accordance
with the present disclosure is the height of a substrate(typically
.about.2 mm) plus two collimator spaces.
SUMMARY OF THE INVENTION
[0012] This section is for the purpose of summarizing some aspects
of the present invention and to briefly introduce some preferred
embodiments. Simplifications or omissions in this section as well
as in the abstract and the title may be made to avoid obscuring the
purpose of this section, the abstract and the title. Such
simplifications or omissions are not intended to limit the scope of
the present invention.
[0013] In general, the present invention pertains to improved
designs of optical devices, particularly for adding or dropping a
selected wavelength or a group of wavelengths as well as
multiplexing a plurality of signals into a multiplexed signal or
demultiplexing a multiplexed signal into several signals. For
simplicity, a group of selected wavelengths or channels will be
deemed or described as a selected wavelength hereinafter. According
to one aspect of the present invention, an assembly is described.
To ensure that all collimators are on one side to facilitate
efficient packaging, all collimators are positioned on both sides
of a substrate. Thus one or more beam folding components are used
to fold a light beam up and down through the collimators on top of
the substrate and bottom of the substrate.
[0014] Depending on implementation, different means are provided to
ensure that the collimators are securely boned to the substrate.
According to one embodiment, wedges are used to hold each of the
collimators. Depending on the shape of the collimators, the wedges
are designed in different shape to prove a best contact with the
collimators.
[0015] The present invention may be implemented in many ways as a
subsystem, a device or a method. According to one embodiment, the
present invention is an optical assembly. The optical assembly
comprises at least a common collimator; a substrate; an array of
channel collimators including an upper set of collimators and a
lower set of collimators, wherein the upper set of collimators is
mounted on top of the substrate, and the lower set of collimators
is mounted on bottom of the substrate; one or more beam folding
components mounted near an end of the substrate, wherein the one or
more of the beam folding components turn a light beam traveling
through the upper set of collimators to the lower set of
collimators, or a light beam traveling through the lower set of
collimators to the upper set of collimators, wherein all of the
collimators and the common collimator are on one side of the beam
folding components.
[0016] Objects, features, and advantages of the present invention
will become apparent upon examining the following detailed
description of an embodiment thereof, taken in conjunction with the
attached drawings
BRIEF DESCRIPTION OF THE DRAWINGS
[0017] These and other features, aspects, and advantages of the
present invention will become better understood with regard to the
following description, appended claims, and accompanying drawings
where:
[0018] FIG. 1 replicates a WDM device disclosed in U.S. Pat. No.
5,583,683;
[0019] FIG. 2A shows that a could be doubled due to the minimum
radius limitation;
[0020] FIG. 2B shows that all the I/O ports are deposed on one side
of a device;
[0021] FIGS. 3A-3C shows some exemplary beam folding
components;
[0022] FIG. 4 replicates an optical device of U.S. Pat. No.
6,847,450 using turning prisms to bend light beams from adding
channel collimators vertical to the main plane (beam cascading
plane);
[0023] FIG. 5 replicates a device of U.S. Pat. No. 7,068,880 that
is similar to that of FIG. 4;
[0024] FIG. 6A shows an structure according to one embodiment of
the present invention;
[0025] FIG. 6B illustrates a ray-tracing plot for the structure of
FIG. 6A;
[0026] FIG. 7A shows an exemplary 4-channel free-space Demux with
one prism block;
[0027] FIG. 7B shows an exemplary corresponding 4-channel
free-space Mux with one prism block;
[0028] FIG. 8 shows that two halves of a prism can even be mounted
to the two horizontal surfaces of the substrate;
[0029] FIG. 9 shows a structure with two reflection filters or
mirrors
[0030] FIG. 10 shows one embodiment overcoming the slant
collimators and uses a prism to redirect the beam so as to keep to
keep the collimator parallel
[0031] FIG. 11 shows another embodiment using a slant mounted
retro-reflection prism to send the beam from the common port to the
lower level and project to a first channel filter and then a first
channel collimator;
[0032] FIG. 12A and FIG. 12B show respectively filters can be
directly bonded with a prisms to avoid the requirement of having a
good sidewall of the substrate;
[0033] FIG. 13 shows a structure with a substrate end for two
extruded widgets;
[0034] FIG. 14A and FIG. 14B show two different mounting means
using wedges;
[0035] FIG. 15A shows an exemplary structure for mounting two
4-channel devices in one enclosure;
[0036] FIG. 15B shows ports of two devices are laid out in a
complementary arrangement;
[0037] FIG. 16A-FIG. 16D demonstrate respectively four coarse WDM
(CWDM) channel plans for Mux/Demux pair ("M" for Mux, "D" for
"Demux");
[0038] FIG. 17A and FIG. 17B show two more different settings from
FIGS. 16A-16D; and
[0039] FIG. 18A shows an exemplary stacking of three devices;
and
[0040] FIG. 18B shows an exemplary stacking of four devices.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
[0041] The detailed description of the present invention is
presented largely in terms of procedures, steps, logic blocks,
processing, or other symbolic representations that directly or
indirectly resemble the operations of optical devices or systems
that can be used in optical networks. These descriptions and
representations are typically used by those skilled in the art to
most effectively convey the substance of their work to others
skilled in the art.
[0042] Reference herein to "one embodiment" or "an embodiment"
means that a particular feature, structure, or characteristic
described in connection with the embodiment can be included in at
least one embodiment of the invention. The appearances of the
phrase "in one embodiment" in various places in the specification
are not necessarily all referring to the same embodiment, nor are
separate or alternative embodiments mutually exclusive of other
embodiments.
[0043] Referring now to the drawings, in which like numerals refer
to like parts throughout the several views. FIG. 6A shows an
structure 600 according to one embodiment of the present invention.
The structure has two levels, an upper level and a lower level,
separated by a substrate 602. A light beam at the upper level is
turned vertically by a trapezoid prism 604 vertically mounted and
then turned again by the same prism 604 to the lower level. As a
result, the beam comes back to the same side of the structure 600,
namely input and output ports can be mounted on one side of the
structure 600.
[0044] FIG. 6B illustrates a ray-tracing plot 650 for the structure
600 of FIG. 6A. The beam from a common collimator at the upper
level is folded by a prism to the lower level, then split by a thin
film filter through which an in-band signal passes. The passed
signal is then coupled out by a collimator, while all other band
signals are directed to the same retro-reflecting prism and folded
to the upper level again. After several rounds of optical splitting
by filters and optical folding by the prism, different band signals
in the incoming signal are dropped to respective ports (all on the
same side).
[0045] This kind of splitting propagation produces a Demux device.
If the beam travels in a reversed manner, the device works as a
combining mode, resulting in a Mux device. It can be appreciated by
those skilled in the art that each of the embodiments described
herein works in either mode (Mux or Demux). FIG. 7A shows an
exemplary 4-channel free-space Demux 700 with one prism block 702
while FIG. 7B shows an exemplary corresponding 4-channel free-space
Mux 720 with one prism block 704.
[0046] As shown in FIG. 7A and FIG. 7B, the prism block or prism
702 or 722 is mounted to the end of the substrate. If the prism is
cut into two halves as shown in FIG. 3B, they may be mounted on the
end vertical surface of the substrate, just like one-prism design.
FIG. 8 shows that two halves of the prism can even be mounted to
the two horizontal surfaces of the substrate. The edges of two
prisms are standing on the extended surfaces of the substrate. The
substrate may be designed in various forms to support two prisms or
two halves of a prism. Any mechanical designs of the substrate that
supports two reflection components (prisms, mirrors, or even
filters) to make a beam for a U-turn shall be considered within
scope of the present invention.
[0047] FIG. 9 shows a structure 900 with two reflection filters or
mirrors. These two mirrors are mounted on one or two slant wedges
attached to the substrate to fold a beam. These wedges may be
separated with the substrate or be part of the substrate. The beam
from a common collimator or a filter hits the mirror above the
substrate and is turned to vertical or similar direction. The
turned beam hits the other mirror underneath the substrate and is
turned again to the reverse direction to the incident direction.
After reflected by the filters on the lower level, the beam comes
back to the lower mirror that turns it to the upper mirror and then
to the upper filter again. Depending on implementation, the mirrors
may be exchangeable with optical filters.
[0048] The design of FIG. 9 takes the benefit of simplicity. But
due to the existence of common collimators being slanted, the fiber
I/O is not entirely one-sided as commonly understood. If the
incidence angle is large, this angular offset of the common port is
serious and may not be acceptable for packaging in some
applications.
[0049] FIG. 10 shows that one embodiment 1000 overcomes the
arrangement of having a slanted collimator and uses a prism to
redirect the beam so as to keep the collimator in parallel. As a
result, a common collimator can be aligned with other channel
collimators.
[0050] FIG. 11 shows another embodiment 1100 using a slant mounted
retro-reflection prism to send the beam from the common port to the
lower level and project to a first channel filter and then a first
channel collimator. Through the reflection of the first filter, the
beam enters the cycle of splitting by filters and folding by a
second prism. The filters can be bonded to the substrate surfaces.
This requires a good sidewall for each of the filters. To avoid the
requirement of having a good sidewall of the substrate, these
filters can be directly bonded with the prisms as shown in FIG. 12A
and FIG. 12B.
[0051] FIG. 13 shows a structure 1300 with a substrate end for two
extruded wegets. Mounting holes are designed in the widgets to hold
the collimators. A type of adhesive (e.g., epoxy) is applied to
secure the position of the collimators to the widget. The mounting
holes are an example to hold the collimators, other means such as
V-grooves may be used to hold the collimators as well.
[0052] Another mounting method is to use flexible bridges or
wedges. To mount a collimator to a flat substrate, the bridge block
has two touch surfaces: one with the collimator, the other with
substrate. Since the substrate is flat, the best contact is a flat
surface. But a collimator has a cylindrical or similar outer shape,
the contact surface can be more flexible. If this contact surface
is also flat, then the bridge block is a wedge. FIG. 14A and FIG.
14B show two different mounting means using such wedges.
[0053] If the surface is curved, curved wedges may be used as shown
respectively in FIG. 14C and FIG. 14D. Depending on implementation,
there are other types of wedges that may be used. The wedges can be
used individually, but for better bonding, the wedges are better to
be used in pair. With a pair of bridges, four contact surfaces are
involved to secure the support between collimators and the
substrate.
[0054] In some network designs, two or more similar devices are
required to be mounted at the same location. Mux/Demux pair is a
typical setting. In one embodiment, an array of Mux/Demux devices
is mounted on one substrate and within one enclosure to save space
and cost. FIG. 15A shows an exemplary structure for mounting two
4-channel devices in one enclosure. The ports of two devices are
laid out in a complementary manner as shown in FIG. 15B.
[0055] For a first device D1, there are three ports ("D1-COM",
"D1-Ch2", and "D1-Ch4") are on the upper row and two ("D1-Ch1" and
"D1-Ch3") on the lower row. For a second device, there are two
ports ("D2-Ch1" and "D2-Ch3") are on the upper row and three ports
("D2-COM","D2-Ch2", and "D2-Ch4") on the lower row. These two
devices operate independently. Two individual optical signal inputs
or outputs "D1-COM" or "D2-COM" port are Demux or Mux,
respectively. The drop or add signals are separated via the channel
ports ("D1-Ch1","D1-Ch2, . . . ).
[0056] It should be noted that the wavelength band for each port
and each device can be allocated in a customizable manner, mostly
based on application request. And each device in the shared
enclosure may have a different wavelength channel layout. FIG.
16A-FIG. 16D demonstrate respectively four coarse WDM (CWDM)
channel plans for Mux/Demux pair ("M" for Mux, "D" for "Demux"). It
should be also noted that the devices in the array can have the
same or different channel count. FIG. 17A and FIG. 17B show two
more different settings.
[0057] More than two devices may be lined up side by side in a
similar fashion and the devices in the array can have the same or
different channel count. FIG. 18A shows an exemplary stacking of
three devices. FIG. 18B shows an exemplary stacking of four
devices.
[0058] While the present invention has been described with
reference to specific embodiments, the description is illustrative
of the invention and is not to be construed as limiting the
invention. Various modifications to the present invention can be
made to the preferred embodiments by those skilled in the art
without departing from the true spirit and scope of the invention
as defined by the appended claim. Accordingly, the scope of the
present invention is defined by the appended claims rather than the
forgoing description of embodiments.
* * * * *