U.S. patent application number 12/243884 was filed with the patent office on 2009-01-29 for optical switch matrix.
Invention is credited to Christopher M. Look, Jeffery J. Maki.
Application Number | 20090028499 12/243884 |
Document ID | / |
Family ID | 39916550 |
Filed Date | 2009-01-29 |
United States Patent
Application |
20090028499 |
Kind Code |
A1 |
Maki; Jeffery J. ; et
al. |
January 29, 2009 |
Optical Switch Matrix
Abstract
A method for routing optical signals within an optical switch
matrix is described herein. In one embodiment, exemplary routing
within the optical switch matrix includes, but is not limited to,
providing a plurality of switching nodes and a plurality of
intermediate wavelengths. Furthermore, any one of a plurality of
input waveguides is coupled with any one of a plurality of output
waveguides, using one or more of the switching nodes and the
intermediate waveguides. In addition, a switching node couples the
respective input waveguide and the respective output waveguide. The
switching node includes a first switch coupling the respective
input waveguide to an intermediate waveguide and a second switch
coupling the intermediate waveguide to the respective output
waveguide. The second switch is an X switch having a first and
second input ports and a first and second output ports, the first
input port receiving the intermediate waveguide and the first
output port coupling to the respective output waveguide
Inventors: |
Maki; Jeffery J.; (Fremont,
CA) ; Look; Christopher M.; (Pleasanton, CA) |
Correspondence
Address: |
BLAKELY SOKOLOFF TAYLOR & ZAFMAN LLP
1279 OAKMEAD PARKWAY
SUNNYVALE
CA
94085-4040
US
|
Family ID: |
39916550 |
Appl. No.: |
12/243884 |
Filed: |
October 1, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
10867948 |
Jun 14, 2004 |
7447397 |
|
|
12243884 |
|
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Current U.S.
Class: |
385/17 ;
385/18 |
Current CPC
Class: |
G02B 6/3546 20130101;
G02B 6/3512 20130101; G02B 6/3588 20130101 |
Class at
Publication: |
385/17 ;
385/18 |
International
Class: |
G02B 6/26 20060101
G02B006/26 |
Claims
1. A method for routing optical signals within an optical switch
matrix, the method comprising: providing a plurality of switching
nodes and a plurality of intermediate waveguides; and coupling any
one of a plurality of input waveguides with any one of a plurality
of output waveguides, using one or more of the switching nodes and
the intermediate waveguides, wherein at least one switching node
includes a first switch coupling an incoming waveguide to an
intermediate waveguide and a second switch coupling the
intermediate waveguide to an outgoing waveguide, and wherein the
second switch includes a first and second input ports and a first
and second output ports, the first input port receiving the
intermediate waveguide and the first output port coupling to the
outgoing waveguide.
2. The method of claim 1, further comprising partially switching at
least one of the second switches to divert at least a portion of an
optical signal traversing through the second output port of the
respective second switch, while routing a remainder of the optical
signal traveling through the first output port.
3. The method of claim 2, further comprising coupling at least one
photonic detector to a second output port of at least one of the
second switches, wherein the photonic detector receives the portion
of the optical signal diverted via the second output port.
4. The method of claim 3, wherein the photonic detector includes a
photo diode.
5. The method of claim 3, wherein the photonic detector detects and
converts the optical signal into one or more electrical signals,
which are used to measure one or more properties of the optical
signal.
6. The method of claim 1, further comprising coupling at least one
of a plurality of auxiliary input waveguides to the second input
port of a second switch of at least one switching node, each of the
auxiliary input waveguides corresponding to each of the plurality
of input waveguides.
7. The method of claim 6, wherein the second switch of the at least
one switching node routes an optical signal received by the at
least one auxiliary input waveguide to one of the output
waveguides, while blocking at least a portion of the corresponding
optical signal received by the corresponding input waveguide.
8. The method of claim 1, wherein the first switch is one of an X
and Y switches having a first and second output ports, wherein the
first output port is coupled to the respective intermediate
waveguide.
9. The method of claim 8, wherein the second output port of the
first switch is coupled to an auxiliary output waveguide
corresponding to the respective output waveguide, and wherein the
first switch is capable of partially switching to divert at least a
portion of an optical signal received by the corresponding input
waveguide to a corresponding auxiliary output waveguide, while a
remainder of the optical signal is routed to the corresponding
output waveguide.
10. The method of claim 1, wherein the first and second switches
are total internal reflection (TIR) switches implemented based on a
carrier injection in a semiconductor material.
11. A method for routing optical signals within an optical switch
matrix, the method comprising: interconnecting any one of the input
waveguides to any one of the output waveguides using at least a
portion of a plurality of switching elements and intermediate
waveguides, wherein at least one of the switching elements includes
a first input port, a first output port, and second output port,
the first input port receiving an incoming waveguide and the first
output port coupling to an outgoing waveguide; and coupling at
least one photonic detector to the second output port of the at
least one switching element, wherein the switching element is
capable of partially switching to divert at least a portion of an
optical signal received from the first input port to the second
output port, while allowing a remainder of the optical signal to be
routed to the first output port, and wherein the respective
photonic detector detects the portion of the optical signal from
the second output port.
12. The method of claim 11, wherein at least one photonic detector
converts the portion of an optical signal into one or more
electrical signals, and wherein the electrical signals are used to
measure one or more attributes of the optical signal.
13. The method of claim 11, wherein the photonic detector includes
a photo diode.
14. The method of claim 11, wherein at least one of the switching
elements is a total internal reflection (TIR) switch implemented
based on a carrier injection in a semiconductor material.
15. A method for routing optical signals within an optical switch
matrix, the method comprising: disposing N input waveguides on an
input side of the matrix, N being an integer greater than 2;
disposing N output waveguides on an output side of the matrix; and
interconnecting any one of the N input waveguides to any one of the
N output waveguides using N switching elements of a plurality of
switching elements and one or more intermediate waveguides.
16. The method of claim 15, wherein at least one of the switching
elements is a total internal reflection (TIR) switch implemented
based on a carrier injection in a semiconductor material.
17. The method of claim 15, wherein at least one of the switching
elements includes a first and second output ports, and wherein the
method further comprises partially switching the at least one
switching element to divert a portion of an optical signal to the
first output port while routing a remainder of the optical signal
to the second output port.
18. The method of claim 17, further comprising coupling a photonic
detector to the first output port to detect and convert the optical
signal into one or more electrical signals, wherein the one or more
electrical signals are used to measure one or more attributes of
the optical signal.
19. A method for routing optical signals within an optical switch
matrix, the method comprising: disposing a plurality of input
waveguides on an input side of the matrix; disposing a plurality of
output waveguides on an output side of the matrix; interconnecting
any one of the input waveguides to any one of the output waveguides
using one or more switching elements and intermediate waveguides;
and disposing a plurality of lateral side elements on one or more
lateral sides other than the input and output side of the matrix,
each of the lateral side elements inwardly directing an optical
signal received from one of the input waveguides towards one of the
output waveguides via at least a portion of the plurality of
switching elements and intermediate waveguides.
20. The method of claim 19, wherein at least one of the switching
elements comprises a first output port and a second output port,
wherein the method further comprises partially switching the
switching element to divert at least a portion of an optical signal
to the first output port while routing a remainder of the optical
signal to the second output port.
21. The method of claim 20, further comprising coupling a photonic
detector to the first output port of at least one switching element
to detect the portion of the optical signal diverted to the first
output port while the remaining portion of the optical signal is
routed to the second output port.
22. The method of claim 21, wherein the photonic detector comprises
a photo diode.
23. The method of claim 21, wherein the at least one of the
switching elements having a photonic detector is located
immediately adjacent to an output waveguide.
24. The method of claim 21, wherein the at least one of the
switching elements having a photonic detector is an interior
switching element within the input and output waveguides and the
lateral side elements.
25. The method of claim 21, wherein the photonic detector detects
and converts the received optical signal to one or more electrical
signals for measuring one or more attributes of the optical
signal.
26. The method of claim 19, wherein at least one of the switching
elements is a total internal reflection (TIR) switch implemented
based on a carrier injection in a semiconductor material.
27. The method of claim 19, wherein at least one of the lateral
side elements comprises a waveguide bend to direct optical signals
from a direction of the input side towards another direction of the
output side.
28. The method of claim 19, wherein at least one of the lateral
side element comprises an optical mirror to direct optical signals
from a direction of the input side towards a direction of the
output side.
29. The method of claim 19, wherein at least one of the lateral
side element comprises a side-switching element to direct optical
signals from a direction of the input side towards another
direction of the output side.
30. The method of claim 29, wherein at least one of the
side-switching element comprises a plurality of output ports, and
wherein the at least one switching element is capable of partially
switching to divert at least a portion of an optical signal to one
of the output ports while routing a remainder of the optical signal
to one or more other output ports.
31. The method of claim 30, further comprises coupling at least one
photonic detector to an output port of the at least one of the
side-switching elements, wherein the photonic detector detects and
converts the optical signal to one or more electrical signals for
analyzing one or more attributes of the optical signal.
32. The method of claim 31, wherein at least one of the
side-switching elements is a total internal reflection (TIR) switch
implemented based on a carrier injection in a semiconductor
material.
33. The method of claim 19, wherein the plurality of lateral side
elements comprises a combination of at least two of a waveguide
bend, an optical mirror, and a side-switching element, to direct
optical signals from a direction of the input side towards another
direction of the output side.
34. The method of claim 33, wherein at least one of the
side-switching elements comprises a plurality of output ports, and
wherein the at least one switching element is capable of partially
switching to divert at least a portion of an optical signal to one
of the output ports while routing a remainder of the optical signal
to one or more other output ports.
35. The method of claim 34, wherein a photonic detector is coupled
to an output port of at least one of the side-switching element to
detect and convert an optical signal to one or more electrical
signals.
36. A method, comprising: coupling an intermediate waveguide to a
first switching element, the first switching element to receive an
optical signal from an incoming waveguide; and coupling a second
switching element to the intermediate waveguide to receive the
directed optical signal from the intermediate waveguide, the second
switching element having a first output port and a second output
port, wherein the first output port outputs at least a portion of
the optical signal to an outgoing waveguide and the second output
port diverts at least a portion of the optical signal for
monitoring purposes.
37. The method of claim 36, further comprising: coupling a photonic
detector to the second output port of the second switching element;
and converting, via the photonic detector, the diverted portion of
the optical signal into one or more electrical signals.
38. The method of claim 37, further comprising measuring one or
more attributes of the optical signal based on the one or more
electrical signals.
39. The method of claim 38, wherein the photonic detector comprises
a photo diode.
40. The method of claim 37, wherein at least one of the first and
second switching elements is a total internal reflection (TIR)
switch implemented based on a carrier injection in a semiconductor
material.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This patent application is a divisional of U.S. patent
application Ser. No. 10/867,948, filed Jun. 14, 2004, now U.S. Pat.
No. ______.
FIELD OF THE INVENTION
[0002] The present invention relates generally to fiber optics.
More particularly, this invention relates to an optical switch
matrix.
BACKGROUND OF THE INVENTION
[0003] Integrated optical switches have been widely used recently.
To divert light from one waveguide to another, the waveguides are
coupled by specific geometric arrangements of the two waveguides in
relation to each other, where the coupling is modified by local
electro-optical manipulation of their indices of refraction.
Typical examples of electro-optical switches include the
Mach-Zehnder interferometer 2.times.2 switch, the directional
coupler 2.times.2 switch, the modal-interference 2.times.2 switch
(e.g., two-mode interference switch, bifurcation optical active
switch), the inode-evolution 2.times.2 switch, the imbalanced
y-branch 1.times.2 switch, the digital-optical switch, and the
total internal reflection (TIR) X-switch. Depending oil the voltage
applied to such switches or in some cases the electrical current
actually, light is thus partly or completely diverted from an input
waveguide to an output waveguide.
[0004] By appropriately combining waveguides and switches, a switch
array (also referred to as switch matrix) is formed to switch light
from multiple input waveguides among multiple output waveguides. A
variety of switch array geometries have been used. Switch arrays
based on geometries such as crossbar geometry can be used to divert
input signals to output channels arbitrarily. Signals from any
input channels can be directed to any output channel, and even to
multiple output channels, in broadcast and multicast transmission
modes.
[0005] FIG. 1A is a layout illustrating a typical switch array
having crossbar geometry. A set of input waveguides 101 crosses a
set of output waveguides 102 via multiple switching nodes, such as
switching node 103, disposed at the crossing points to divert an
incoming optical signal from any one of the input waveguides 101 to
any one of the output waveguides 102. FIG. 1B is an enlarged
portion of switching node 103 shown in FIG. 1A. Referring to FIG.
1B, an incoming optical signal traveling along waveguide 104 is
routed or diverted to one of waveguides 105 and 106 via the
switching element 110. The switching element 110 may be referred to
herein as an X switch having two input ports and two output
ports.
[0006] Single crossbar switching elements are used in the
structures shown in FIGS. 1A and 1B. Alternatively, a double
crossbar switching node may also be used in place of switching node
103. FIG. 2A is a layout illustrating a typical double crossbar
switching node. The double crossbar switching node 200 includes
switches 203 and 204, which are Y switches. In order to reach from
waveguide 201 to waveguide 202, the incoming optical signal is
routed by switch 204 onto an intermediate waveguide 205 and routed
again by switch 203 onto waveguide 202. In addition, an optical
mirror may be used to direct an optical signal from one direction
into another direction. FIG. 2B is a layout illustrating a typical
optical mirror. The optical mirror 253 is used to direct an
incoming optical signal traveling waveguide 251 from one direction
to waveguide 252 of different direction.
[0007] A typical switch employs the thermo-optic effect in a
localized manner to control the refractive index within polymer
waveguide structures to switch and attenuate the optical signals,
which may limit the switching speed of the switch. Further, there
has been a lack of commercially available switches possessing
microsecond operation that have integrated variable optical
attenuators and integrated optical power monitoring. The lack of
integrated power monitoring means external components are required,
which makes the overall approach more cumbersome and bulky.
SUMMARY OF THE INVENTION
[0008] A method for routing optical signals within an optical
switch matrix is described herein. In one embodiment, exemplary
routing within the optical switch matrix includes, but is not
limited to, providing a plurality of switching nodes and a
plurality of intermediate wavelengths. Furthermore, any one of a
plurality of input waveguides is coupled with any one of a
plurality of output waveguides, using one or more of the switching
nodes and the intermediate waveguides. In addition, a switching
node couples the respective input waveguide and the respective
output waveguide. The switching node includes a first switch
coupling the respective input waveguide to an intermediate
waveguide and a second switch coupling the intermediate waveguide
to the respective output waveguide. The second switch is an X
switch having a first and second input ports and a first and second
output ports, the first input port receiving the intermediate
waveguide and the first output port coupling to the respective
output waveguide.
[0009] Other features of the present invention will be apparent
from the accompanying drawings and from the detailed description
which follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] The present invention is illustrated by way of example and
not limitation in the figures of the accompanying drawings in which
like references indicate similar elements.
[0011] FIG. 1A is a layout illustrating a typical switch array
having crossbar geometry.
[0012] FIG. 1B is a layout illustrating a typical X switching
element, which may be used in one embodiment of the invention.
[0013] FIG. 2A is a layout illustrating a typical double crossbar
switching element, which may be used in one embodiment of the
invention.
[0014] FIG. 2B is a layout illustrating a typical optical mirror,
which may be used in one embodiment of the invention.
[0015] FIG. 3 is a block diagram illustrating an exemplary optical
switch fabric according to one embodiment of the invention.
[0016] FIGS. 4A and 4B are layouts illustrating an exemplary
optical switching node according to certain embodiments of the
invention.
[0017] FIGS. 5A-5B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to one
embodiment of the invention.
[0018] FIGS. 6A-6B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to an
alternative embodiment of the invention.
[0019] FIGS. 7A-7B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to another
alternative embodiment of the invention.
[0020] FIGS. 8A-8B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to another
embodiment of the invention.
[0021] FIGS. 9A-9B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to another
embodiment of the invention.
[0022] FIGS. 10A-10B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to another
embodiment of the invention.
[0023] FIG. 11 is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to another embodiment
of the invention.
[0024] FIG. 12 is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to another embodiment
of the invention.
[0025] FIGS. 13A-13B are layouts illustrating a plain view of
exemplary optical switch matrix architecture according to another
embodiment of the invention.
[0026] FIGS. 14A-14B are layouts illustrating routing algorithm
within a switch matrix according to certain embodiments of the
invention.
DETAILED DESCRIPTION
[0027] An optical switch matrix is described herein. In the
following description, numerous specific details are set forth
(e.g., such as logic resource partitioning/sharing/duplication
implementations, types and interrelationships of system components,
and logic partitioning/integration choices). However, it is
understood that embodiments of the invention may be practiced
without these specific details. In other instances, well-known
circuits, software instruction sequences, structures and techniques
have not been shown in detail in order not to obscure the
understanding of this description.
[0028] References in the specification to "one embodiment", "an
embodiment", "an example embodiment", etc., indicate that the
embodiment described may include a particular feature, structure,
or characteristic, but every embodiment may not necessarily include
the particular feature, structure, or characteristic. Moreover,
such phrases are not necessarily referring to the same embodiment.
Further, when a particular feature, structure, or characteristic is
described in connection with an embodiment, it is submitted that it
is within the knowledge of one skilled in the art to effect such
feature, structure, or characteristic in connection with other
embodiments whether or not explicitly described.
[0029] In the following description and claims, the terms "coupled"
and "connected," along with their derivatives, may be used. It
should be understood that these terms are not intended as synonyms
for each other. Rather, in particular embodiments, "connected" may
be used to indicate that two or more elements are in direct contact
with each other (e.g., physically, electrically, optically, etc.).
"Coupled" may similarly mean that two or more elements are in
direct contact (physically, electrically, optically, etc.).
However, "coupled" may alternatively mean that two or more elements
are not in direct contact with each other, but yet still co-operate
or interact with each other.
[0030] FIG. 3 is a block diagram illustrating an exemplary optical
switch fabric according to one embodiment of the invention.
Referring to FIG. 3, exemplary switch fabric 300 includes, but is
not limited to, an optical switch matrix (also referred to as an
optical switch array) 302 having multiple switching elements to
receive multiple input optical fibers 301, one or more variable
optical attenuators (VOAs) 303, and one or more photonic detectors
305 to monitor, via one or more tap mechanisms 304, the optical
signals traveling along multiple output optical fibers 306.
[0031] In one embodiment, the switch matrix 302 may be an 8.times.8
switch matrix that routes any one of the optical signals received
by the input fibers 301 to any one of the output fibers 306 using
multiple optoelectrical switches, such as, for example, directional
couplers, BOA couplers, digital-optical-switches, and X or Y
switches. In a typical embodiment, the switches (also referred to
as optical cross-connect switches, switching elements, switching
nodes, and/or switches) employed in the exemplary switch matrix 302
may be able to perform one microsecond operation (or shorter in
time) with fully integrated variable optical attenuation and output
optical power monitoring, which enables constant output power
operation over multiple channels. In one embodiment, the switches
employed within the switch matrix 302 may be manufactured using a
semiconductor material and local manipulation of the refractive
index by the carrier-induced plasma effect generated by
appropriately placed electrodes and current injected from the
application of a forward-biased voltage (closely related are the
Pockels and Kerr effects that rely upon strong electric fields
rather than strong electrical currents).
[0032] The switches may possess multiple functionality, such as,
for example, attenuation, and power monitoring, etc. For example,
according to one embodiment, at least one of the switching elements
that make up the switching matrix may be capable of partially
switching to divert a portion of an optical signal to one output
port while routing the remaining portion of the optical signal to
another output port. Note that although components 302-304 are
shown as separate functional blocks, it will be appreciated that
these components are integrated within each other on a single
substrate (e.g., single integrated chip).
[0033] FIG. 4A is a layout illustrating an exemplary optical
switching node according to one embodiment of the invention. In one
embodiment, exemplary switching node (also referred to as a
coupling node) 400 includes, but not limited to, a first switching
element to receive an optical signal from an incoming waveguide, an
intermediate waveguide coupled to the first switching element to
received the optical signal directed by the first switching
element, and a second switching element coupled to the intermediate
waveguide to receive the directed optical signal from the
intermediate waveguide, the second switching element having a first
output port and a second output port, wherein the first output port
outputs at least a portion of the optical signal to an outgoing
waveguide and the second output port diverts at least a portion of
the optical signal for monitoring purposes.
[0034] Referring to FIG. 4A, the exemplary switching node 400
includes a first switching element 401, a second switching element
402, and an intermediate waveguide 403. The first switching element
401 receives an optical signal from an incoming waveguide 410. The
first switching element 401 can either allow the optical signal to
continue traveling through waveguide 411 or switches the optical
signal to the intermediate waveguide 403. In one embodiment, the
first switching element 401 may be capable of partially switching
that allows a portion of the optical signal to continue traveling
through waveguide 411, while the remaining portion of the optical
signal is rerouted to the intermediate waveguide 403. In this
example, the first switching element 401 is a Y switching element
having one input port and two output ports. Alternatively, the
first switching element 401 may be an X switching having two input
ports and two output ports.
[0035] The second switching element 402 receives the optical signal
from the intermediate waveguide 403 and may route the optical
signal to another waveguide 420. In one embodiment, the second
switching element 402 may be an X switching element having two
input ports and two output ports. According to one embodiment, one
of the output ports is coupled to the outgoing waveguide 420, while
the other output port 404 may be used for other purposes, such as,
monitoring or testing purposes. In one embodiment, the second
switching element 402 is capable of partially switching to divert a
portion of the optical signal received from the intermediate
waveguide 403 to the outgoing waveguide 420, while routing the
remaining portion of the optical signal to the other output port
404. Optionally, according to one embodiment, one or more
monitoring or testing devices 405 may be coupled to the output port
404 for monitoring and/or testing purposes. For example, device 405
may be a photonic detector that detects an optical signal received
from the output port 404 and converts the received optical signal
into one or more electrical signals for the purposes of monitoring
and/or testing purposes. In a particular embodiment, the device 405
may be photo diode device.
[0036] FIG. 4B is a layout of illustrating an exemplary optical
switching node according to an alternative embodiment of the
invention. In this embodiment, both switching elements 401 and 402
are switching elements having multiple input ports and multiple
output ports, such as, for example, X switching elements. As a
result, one or more monitoring and/or testing devices 405 and 407
may be coupled to the auxiliary output ports 404 and 406
respectively. The monitoring and/or testing devices 405 and 407 may
be a photonic detector, such as, for example, a photo diode. Other
configurations may exist.
[0037] FIG. 5A is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. In one embodiment, the exemplary switch matrix 500
includes, but is not limited to, multiple input waveguides disposed
on an input side of the matrix, multiple output waveguides disposed
on an output side of the matrix, multiple switching elements and
intermediate waveguides to interconnect any one of the input
waveguides and any one of the output waveguides, and multiple
lateral side elements disposed on one or more lateral sides other
than the input and output side of the matrix, each of the lateral
side elements inwardly directing an optical signal received from
one of the input waveguides towards one of the output waveguides
via at least a portion of the plurality of switching elements and
intermediate waveguides.
[0038] In another embodiment, the exemplary switch matrix 500
includes, but is not limited to, N input waveguides disposed on an
input side of the matrix, N being an integer greater than 2, N
output waveguides disposed on an output side of the matrix,
multiple switching elements and intermediate waveguides to
interconnect any one of the N input waveguides and any one of the N
output waveguides, where an optical signal received at one of the N
input waveguides reaches one of the N output waveguides via N
switching elements of the multiple switching elements.
[0039] Referring to FIG. 5A, the exemplary switch matrix 500
includes an input side where multiple input waveguides 501 are
disposed and an output side where multiple output waveguides 502
are disposed. The input waveguides 501 are used to receive input
optical signals. The input optical signal may be one of the
wavelengths (also referred to as lambdas), for example, in a
wavelength division multiplex (WDM) network or a dense WDM (DWDM)
network. The switch matrix 500 may also be referred to as N.times.N
switch matrix, where there are N input waveguides and N output
waveguides. In a particular embodiment, there are 8 inputs and 8
outputs. It will be appreciated that more or less inputs and/or
outputs may be implemented.
[0040] An optical signal from any one of the input waveguides 501
may be routed to any one of the output waveguides 502 via one or
more optical switching elements such as switching element 503 and
one or more intermediate waveguides between the input waveguides
501 and output waveguides 502, such as, for example, intermediate
waveguides 504 and 506. The elements disposed on the lateral sides
510 and 520 other than the input and output sides 501 and 502 may
be referred to as lateral side elements. The elements disposed
within the input and output sides 501-502, and the lateral sides
510 and 520 may be referred to as interior elements. For example,
switching element 511 may be referred to as one of the interior
elements, while element 505 may be referred to as a lateral side
element. The layout 500 shown in FIG. 5A may also be referred to as
a colinear layout, which forms a rectangular
photonic-integrated-circuit chip that is long and narrow.
[0041] Some of the switching elements of FIG. 5A may include one or
more physical switches (e.g., sub-switches) therein. In one
embodiment, the switching elements may be total internal reflection
(TIR) switches which may be implemented based on a carrier
injection technology in a semiconductor material. In one
embodiment, some of the switching elements may be able to function
as variable optical attenuators (VOAs), in addition to the normal
switching functionality. For example, according to one embodiment,
a switching element may include multiple output ports, such as, for
example, a first output port and a second output port. The
switching element may be capable of partially switching to divert
at least a portion of the optical signal received from an input
port of the switching element to a first output port, while
directing the remaining portion of the optical signal to the second
output port. As a result, the switching element functions as a part
of a VOA.
[0042] In one embodiment, a switching element may be an X switch
having two input ports and two output ports, such as, for example,
switching node 103 of FIG. 1B. Alternatively, a switching element
may be a Y switch having one input port and two output ports, or
one output port and two input ports, similar to those shown in FIG.
2A. According to one embodiment, one of the output ports may be
used as an auxiliary output port and one of the input ports may be
used as an auxiliary input port. An auxiliary input optical signal
may be fed into the auxiliary input port and routed to the
corresponding regular output port, while blocking the regular input
optical signal from the same output port (e.g., similar to add/drop
functions).
[0043] In one embodiment, a photonic detector may be coupled to an
output port of some switching elements, where the photonic detector
may receive a portion of an optical signal that has been diverted
by the respective switching element and convert the received
optical signal into one or more electrical signals for a variety of
purposes, such as, for example, monitoring and/or diagnostic
purposes. In one embodiment, the photonic detector may be a photo
diode.
[0044] Referring to FIG. 5A, according to one embodiment, on the
edges or sides other than the input and output sides (e.g., lateral
sides), one or more lateral side elements 505 may be used to change
the direction of the optical signals along the respective edge
towards the output side. In one embodiment, the lateral side
element 505 may be an optical mirror. In one embodiment, the
optical mirrors may be waveguide TIR mirrors. A waveguide TIR
mirror uses an interface with air to generate the TIR effect. Other
elements or configurations may be implemented. FIG. 5B is an
enlarged version of a portion of the switch matrix shown in FIG.
5A.
[0045] FIG. 6A is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to an alternative
embodiment of the invention. Referring to FIG. 6A, the exemplary
switch matrix 600 includes an input side where multiple input
waveguides 601 are disposed and an output side where multiple
output waveguides 602 are disposed. The input waveguides 601 are
used to receive input optical signals. The input optical signal may
be one of the wavelengths (also referred to as lambdas), for
example, in a wavelength division multiplex (WDM) network or a
dense WDM (DWDM) network. The switch matrix 600 may also be
referred to as N.times.N switch matrix, where there are N input
waveguides and N output waveguides.
[0046] An optical signal from any one of the input waveguides 601
may be routed to any one of the output waveguides 602 via one or
more optical switching elements such as switching element 603 and
one or more intermediate waveguides between the input waveguides
601 and output waveguides 602, such as, for example, intermediate
waveguides 604 and 606.
[0047] Some of the switching elements of FIG. 6A may include one or
more physical switches (e.g., sub-switches) therein. In one
embodiment, the switching elements may be total internal refraction
(TIR) switches which may be implemented based on a carrier
injection technology in a semiconductor material. In one
embodiment, some of the switching elements may be able to function
as variable optical attenuators (VOAs), in addition to the normal
switching functionality. For example, according to one embodiment,
a switching element may include multiple output ports, such as, for
example, a first output port and a second output port. The
switching element may be capable of partially switching to divert
at least a portion of the optical signal received from an input
port of the switching element to a first output port, while
directing the remaining portion of the optical signal to the second
output port. As a result, the switching element functions as a part
of a VOA.
[0048] In one embodiment, a switching element may be an X switch
having two input ports and two output ports, such as, for example,
switching node 103 of FIG. 1B. Alternatively, a switching element
may be a Y switch having one input port and two output ports, or
one output port and two input ports, similar to those shown in FIG.
2A. According to one embodiment, one of the output ports may be
used as an auxiliary output port and one of the input ports may be
used as an auxiliary input port. An auxiliary input optical signal
may be fed into the auxiliary input port and routed to the
corresponding regular output port, while blocking the regular input
optical signal from the same output port (e.g., similar to add/drop
functions).
[0049] In one embodiment, a photonic detector may be coupled to an
output port of some switching elements, where the photonic detector
may receive a portion of an optical signal that has been diverted
by the respective switching element and convert the received
optical signal into one or more electrical signals for a variety of
purposes, such as, for example, monitoring and/or diagnostic
purposes. In one embodiment, the photonic detector may be a photo
diode.
[0050] In this example, instead of using optical mirrors as the
lateral side elements on the lateral sides as shown in FIGS. 5A and
5B, one or more additional switching elements, such as switching
element 605, may be used to direct the optical signals from one
direction to another direction.
[0051] FIG. 6B is an enlarged version of a portion of the switch
matrix shown in FIG. 6A. Switching element 605 may have one or more
characteristics described above. For example, switching element 605
may include multiple output ports and the switching element 605 may
be capable of partially switching that directs a portion of the
optical signal to one or more output ports. In one embodiment, one
of the output ports of switching element 605 may be coupled to a
photonic detector that receives at least a portion of the optical
signal for a variety of purposes, such as, for example, monitoring
and/or diagnostic purposes. Alternatively, one of the output ports
may be used as an auxiliary output, in addition to the regular
outputs. Other elements or configurations may be implemented.
[0052] FIG. 7A is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to another alternative
embodiment of the invention. Referring to FIG. 7A, the exemplary
switch matrix 700 includes an input side where multiple input
waveguides 701 are disposed and an output side where multiple
output waveguides 702 are disposed. The input waveguides 701 are
used to receive input optical signals. The input optical signal may
be one of the wavelengths (also referred to as lambdas), for
example, in a wavelength division multiplex (WDM) network or a
dense WDM (DWDM) network. The switch matrix 700 may also be
referred to as N.times.N switch matrix, where there are N input
waveguides and N output waveguides.
[0053] An optical signal from any one of the input waveguides 701
may be routed to any one of the output waveguides 702 via one or
more optical switching elements such as switching element 703 and
one or more intermediate waveguides between the input waveguides
701 and output waveguides 702, such as, for example, intermediate
waveguides 704 and 706.
[0054] Some of the switching elements of FIG. 7A may include one or
more physical switches (e.g., sub-switches) therein. In one
embodiment, the switching elements may be total internal refraction
(TIR) switches which may be implemented based on a carrier
injection technology in a semiconductor material. In one
embodiment, some of the switching elements may be able to function
as variable optical attenuators (VOAs), in addition to the normal
switching functionality. For example, according to one embodiment,
a switching element may include multiple output ports, such as, for
example, a first output port and a second output port. The
switching element may be capable of partially switching to divert
at least a portion of the optical signal received from an input
port of the switching element to a first output port, while
directing the remaining portion of the optical signal to the second
output port. As a result, the switching element functions as a part
of a VOA.
[0055] In one embodiment, a switching element may be an X switch
having two input ports and two output ports, such as, for example,
switching node 103 of FIG. 1B. Alternatively, a switching element
may be a Y switch having one input port and two output ports, or
one output port and two input ports, similar to those shown in FIG.
2A. According to one embodiment, one of the output ports may be
used as an auxiliary output port and one of the input ports may be
used as an auxiliary input port. An auxiliary input optical signal
may be fed into the auxiliary input port and routed to the
corresponding regular output port, while blocking the regular input
optical signal from the same output port (e.g., similar to add/drop
functions).
[0056] In one embodiment, a photonic detector may be coupled to an
output port of some switching elements, where the photonic detector
may receive a portion of an optical signal that has been diverted
by the respective switching element and convert the received
optical signal into one or more electrical signals for a variety of
purposes, such as, for example, monitoring and/or diagnostic
purposes. In one embodiment, the photonic detector may be a photo
diode.
[0057] In this example, instead of using optical mirrors on the
edges other than the input and output sides as shown in FIGS. 5A
and 5B, or the additional switching elements as shown in FIGS. 6A
and 6B, one or more waveguide bends, such as waveguide bend 705,
may be used to direct the optical signals from one direction to
another direction. Other elements or configurations may be
implemented. FIG. 7B is an enlarged version of a portion of the
switch matrix shown in FIG. 7A.
[0058] FIG. 8A is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. In one embodiment, the exemplary switch matrix 800
includes, but is not limited to, multiple input waveguides disposed
on an input side of the matrix, multiple output waveguides disposed
on an output side of the matrix, multiple switching elements and
intermediate waveguides to interconnect any one of the input
waveguides and any one of the output waveguides, each of the
switching elements having a first output port and a second output
port, where at least one of the switching elements adjacent to one
of the output waveguides is capable of partially switching to
divert at least a portion of an optical signal to the first output
port while routine a remainder of the optical signal to the second
output port, and for at least one of the switching elements
adjacent to one of the output waveguides, a photonic detector
coupled to the first output port while an output waveguide is
coupled to the second output port.
[0059] Referring to FIG. 8A, similar to the structure shown in FIG.
5A, the exemplary switch matrix 800 includes an input side where
multiple input waveguides 801 are disposed and an output side where
multiple output waveguides 802 are disposed. The input waveguides
801 are used to receive input optical signals. The input optical
signal may be one of the wavelengths (also referred to as lambdas),
for example, in a wavelength division multiplex (WDM) network or a
dense WDM (DWDM) network. The switch matrix 800 may also be
referred to as N.times.N switch matrix, where there are N input
waveguides and N output waveguides.
[0060] An optical signal from any one of the input waveguides 801
may be routed to any one of the output waveguides 802 via one or
more optical switching elements such as switching element 803 and
one or more intermediate waveguides between the input waveguides
801 and output waveguides 802, such as, for example, intermediate
waveguides 804 and 806. Some of the switching elements of FIG. 8
may include one or more characteristics of switching elements shown
in FIGS. 5A and 5B.
[0061] According to one embodiment, on the edges or sides other
than the input and output sides, one or more optical mirrors, such
as optical mirror 805, may be used to change the direction of the
optical signals along the respective edge towards the output side.
In one embodiment, the optical mirrors may be waveguide TIR
mirrors. A waveguide TIR mirror uses an interface with air to
generate the TIR effect.
[0062] In addition, according to one embodiment, one or more
switching elements that are immediately adjacent to or directly
coupled to one or more output waveguides 802, such as, for example,
switching element 808, may include multiple output ports. One of
the output ports may be coupled to one of the output waveguides 802
while another one of the output ports may be coupled to a photonic
detector, such as, for example, photonic detector 807. The photonic
detector may receive a portion of an optical signal that has been
diverted by the respective switching element and convert the
received optical signal into one or more electrical signals for a
variety of purposes, such as, for example, monitoring and/or
diagnostic purposes. Other elements or configurations may be
implemented. FIG. 8B is an enlarged version of a portion of the
structure shown in FIG. 8A.
[0063] FIG. 9A is layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. In one embodiment, the exemplary switch matrix 900
includes, but is not limited to, multiple input waveguides disposed
on an input side of the matrix, multiple output waveguides disposed
on an output side of the matrix, multiple switching elements and
intermediate waveguides to interconnect any one of the input
waveguides and any one of the output waveguides, each of the
switching elements having a first output port and a second output
port, where at least one of the switching elements disposed along
one or more sides other than the input and output sides of the
matrix is capable of partially switching to divert at least a
portion of an optical signal to the first output port while routing
a remainder of the optical signal to the second output port, and
for at least one of the switching elements that is capable of
partially switching, a photonic detector coupled to the first
output port while a waveguide is coupled to the second output
port.
[0064] Referring to FIG. 9A, similar to the structures shown in
FIGS. 5A and 6A, the exemplary switch matrix 900 includes an input
side where multiple input waveguides 901 are disposed and an output
side where multiple output waveguides 902 are disposed. The input
waveguides 901 are used to receive input optical signals. The input
optical signal may be one of the wavelengths (also referred to as
lambdas), for example, in a wavelength division multiplex (WDM)
network or a dense WDM (DWDM) network.
[0065] An optical signal from any one of the input waveguides 901
may be routed to any one of the output waveguides 902 via one or
more optical switching elements such as switching element 903 and
one or more intermediate waveguides between the input waveguides
901 and output waveguides 902, such as, for example, intermediate
waveguides 904 and 906. Some of the switching elements of FIG. 9A
may include one or more characteristics of switching elements
described above and shown in FIGS. 5A and 6A.
[0066] According to one embodiment, on the edges or sides other
than the input and output sides, one or more optical mirrors, such
as optical mirror 905, may be used to change the direction of the
optical signals along the respective edge towards the output side.
In one embodiment, the optical mirrors may be waveguide TIR
mirrors. A waveguide TIR mirror uses an interface with air to
generate the TIR effect. Alternatively, some of the optical mirrors
disposed on the edges other than the input and output sides may be
replaced with additional switching elements, such as, for example,
switching element 908. It will be appreciated that a combination of
an optical mirror, an optical switch, a waveguide bend, and/or
other redirection couplers may be utilized.
[0067] In one embodiment, switching element 908 may include
multiple output ports. One of the output ports may be coupled to
one of the an intermediate waveguide such as intermediate waveguide
904 or an output waveguide, while another one of the output port
may be coupled to a photonic detector, such as, for example,
photonic detector 907. The photonic detector may receive a portion
of an optical signal that has been diverted by the respective
switching element and convert the received optical signal into one
or more electrical signals for a variety of purposes, such as, for
example, monitoring and/or diagnostic purposes. Other elements or
configurations may be implemented. FIG. 9B is an enlarged version
of a portion of the structure shown in FIG. 9A.
[0068] FIG. 10A is layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. In one embodiment, the exemplary switch matrix 1000
includes, but is not limited to, multiple input waveguides,
multiple output waveguides, for each of the input waveguides and
each of the output waveguides, a switching node coupling the
respective input waveguide and the respective output waveguide,
where the switching node includes a first switch coupling the
respective input waveguide to an intermediate waveguide and a
second switch coupling the intermediate waveguide to the respective
output waveguide, and wherein the second switch is an X switch
having a first and second input ports and a first and second output
ports, the first input port receiving the intermediate waveguide
and the first output port coupling to the respective output
waveguide.
[0069] Referring to FIG. 10A, similar to the structures shown in
FIG. 5A, the exemplary switch matrix 1000 includes an input side
where multiple input waveguides 1001 are disposed and an output
side where multiple output waveguides 1002 are disposed. The input
waveguides 1001 are used to receive input optical signals. The
input optical signal may be one of the wavelengths (also referred
to as lambdas), for example, in a wavelength division multiplex
(WDM) network or a dense WDM (DWDM) network.
[0070] An optical signal from any one of the input waveguides 1001
may be routed to any one of the output waveguides 1002 via one or
more optical switching nodes such as switching node 1003 and one or
more intermediate waveguides between the input waveguides 1001 and
output waveguides 1002, such as, for example, intermediate
waveguides 1004 and 1006. Some of the switching elements of FIG.
10A may include one or more characteristics of switching elements
described above and shown in FIG. 5A.
[0071] According to one embodiment, on the edges or sides other
than the input and output sides, one or more optical mirrors, such
as optical mirror 1005, may be used to change the direction of the
optical signals along the respective edge towards the output side.
In one embodiment, the optical mirrors may be waveguide TIR
mirrors. A waveguide TIR mirror uses an interface with air to
generate the TIR effect. Alternatively, some of the optical mirrors
disposed on the edges other than the input and output sides may be
replaced with additional switching elements and/or waveguide bends,
similar to those shown in FIGS. 9A and 9B.
[0072] In one embodiment, switching node 1003 may include multiple
switches therein. In order to route an optical signal from one
waveguide to another waveguide, multiple switches within the
switching node may be utilized. For example, referring to FIG. 10B,
which is an enlarged version of a portion of exemplary switch
matrix 1000 of FIG. 10A, in order to route an optical signal from
waveguide 1006 to waveguide 1004, switches 1008 and 1009 of
switching node 1003 may be utilized. That is, the optical signal
traveling along waveguide 1006 may be switched onto intermediate
waveguide 1007 via switch 1009. The optical signal traveling along
the intermediate waveguide 1007 is then switched via the switch
1008 onto the target waveguide 1004.
[0073] In one embodiment, the switches 1008-1009 may be X switches
having two input ports and two output ports, which may be able to
switch optical signals along the waveguides 1010-1011.
Alternatively, switches 1008-1009 may be Y switches.
[0074] In one embodiment, some of the output ports that are not
used by the optical signals may be coupled to a photonic detector.
The photonic detector may receive a portion of an optical signal
that has been diverted by the respective switching element and
convert the received optical signal into one or more electrical
signals for a variety of purposes, such as, for example, monitoring
and/or diagnostic purposes. Other elements or configurations may be
implemented. Other configurations may be implemented.
[0075] FIG. 11 is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to another embodiment
of the invention. Referring to FIG. 11, similar to the structures
shown in FIGS. 5A and 5B, the exemplary switch matrix 1100 includes
an input side where multiple input waveguides 1101-1108 are
disposed and an output side where multiple output waveguides
1109-1116 are disposed. The input wave guides 1101-1108 are used to
receive input optical signals. The input optical signal may be one
of the wavelengths (also referred to as lambdas), for example, in a
wavelength division multiplex (WDM) network or a dense WDM (DWDM)
network.
[0076] An optical signal from any one of the input waveguides
1101-1108 may be routed to any one of the output waveguides
1109-1116 via one or more optical switching nodes and one or more
intermediate waveguides between the input waveguides 1101-1108 and
output waveguides 1109-1116. Some of the switching elements of FIG.
11 may include one or more characteristics of switching elements
described above. For example, a switching node may be an X or a Y
switching element. Alternatively, a switching node may be a double
crossbar structures having an X and a Y switching elements shown in
FIGS. 4A and 4B or alternatively, two Y switching elements.
[0077] In one embodiment, some of the switching elements may
include multiple output ports and one of the output ports may be
coupled to one or more photonic detectors. A photonic detector may
receive a portion of an optical signal that has been diverted by
the respective switching element and convert the received optical
signal into one or more electrical signals for a variety of
purposes, such as, for example, monitoring and/or diagnostic
purposes. Other elements or configurations may be implemented.
[0078] In addition, an extra set of waveguides 1117-1124 on the
input side may be used as auxiliary input waveguides. An auxiliary
optical signal may be fed into one of the auxiliary input
waveguides 1117-1124 and routed to the corresponding output
waveguides 1109-1116. In the case that an auxiliary input optical
signal is received, the corresponding regular input waveguide from
the input waveguides 1101-1108 may effectively be blocked from any
output waveguide by simply allowing it to pass through one or more
switching elements to its respective alternative output 1125-1132
(e.g., auxiliary output waveguides). This configuration effectively
functions similar to those performed by an add/drop multiplexer
(ADM). Other configurations may be implemented.
[0079] FIG. 12 is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. In one embodiment, exemplary switch matrix 1200
includes, but is not limited to, multiple input waveguides and
multiple output waveguides, for each of the input waveguides and
each of the output waveguides, a switching element coupling the
respective input waveguide and the respective output waveguide,
where the switching element includes a first and second input ports
and a first and second output ports, the first input port receiving
the respective input waveguide and the first output port coupling
to the respective output waveguide, and at least one photonic
detector coupled to the second output port of at least one
switching element, where the switching element is capable of
partially switching to divert at least a portion of an optical
signal received from one of the first and second input ports to the
second output port, while allowing a remainder of the optical
signal to be routed to the first output port, and where the
respective photonic detector detects the portion of the optical
signal from the second output port.
[0080] Referring to FIG. 12, similar to the structures shown in
FIG. 1A, the exemplary switch matrix 1200 includes an input side
where multiple input waveguides 1201 are disposed and an output
side where multiple output waveguides 1202 are disposed. The input
waveguides 1201 are used to receive input optical signals. The
input optical signal may be one of the wavelengths (also referred
to as lambdas), for example, in a wavelength division multiplex
(WDM) network or a dense WDM (DWDM) network.
[0081] An optical signal from any one of the input waveguides 1201
may be routed to any one of the output waveguides 1202 via one or
more optical switching nodes such as switching node 1205 and one or
more intermediate waveguides between the input waveguides 1201 and
output waveguides 1202, such as, for example, intermediate
waveguides 1204 and 1206. Some of the switching elements of FIG. 12
may include one or more characteristics of switching elements
described above. For example, switching node 1205 may be a type of
X-switch. Alternatively, switching node 1205 may include multiple
switches therein, similar to the double crossbar structures shown
in FIGS. 10A-10B and 11A-11B.
[0082] In one embodiment, some of the switching elements,
particularly, those relatively close to the output waveguides 1202
may be coupled to one or more photonic detectors, such as, for
example, photonic detectors 1203. The locations of the photonic
detectors 1203 are shown for the purposes of illustrations only.
Other locations may be implemented. The photonic detector may
receive a portion of an optical signal that has been diverted by
the respective switching element and convert the received optical
signal into one or more electrical signals for a variety of
purposes, such as, for example, monitoring and/or diagnostic
purposes. Other elements or configurations may be implemented.
[0083] In addition, an extra set of waveguides 1204 on the input
side may be used as auxiliary input waveguides. An auxiliary
optical signal may be fed into one of the auxiliary input
waveguides 1204 and routed to the corresponding output waveguides
1202. In the case that an auxiliary input optical signal is
received, the corresponding regular input waveguide from the input
waveguides 1201 may effectively be blocked from any output
waveguide by simply allowing it to pass through one or more
switching elements to its respective alternative output 1203. This
configuration effectively functions similar to those performed by
an add/drop multiplexer (ADM). Other configurations may be
implemented.
[0084] FIG. 13A is a layout illustrating a plain view of exemplary
optical switch matrix architecture according to one embodiment of
the invention. Referring to FIG. 13A, similar to the structures
shown in FIG. 12, the exemplary switch matrix 1300 includes an
input side where multiple input waveguides 1301 are disposed and an
output side where multiple output waveguides 1302 are disposed. The
input waveguides 1301 are used to receive input optical signals.
The input optical signal may be one of the wavelengths (also
referred to as lambdas), for example, in a wavelength division
multiplex (WDM) network or a dense WDM (DWDM) network. Input
waveguides 1304 may be used as auxiliary input waveguides.
[0085] An optical signal from any one of the input waveguides 1301
may be routed to any one of the output waveguides 1302 via one or
more optical switching nodes such as switching node 1305 and one or
more intermediate waveguides between the input waveguides 1301 and
output waveguides 1302. Some of the switching nodes of FIG. 13A may
include one or more characteristics of switching elements described
above. In one embodiment, some of the switching nodes may include
multiple input and/or output ports, similar to those shown in FIGS.
4A and 4B. In addition, instead of using photonic detectors similar
to photonic detectors 1203 of FIG. 12, auxiliary output waveguides
1303 may be implemented. Other configurations, such as, for
example, one or more photonic detectors may be coupled to an output
port of a switch of some switching nodes, as shown in FIG. 13B.
[0086] FIGS. 14A and 14B are layouts illustrating an exemplary
routing algorithm within an optical switch matrix, according to one
embodiment of the invention. In one embodiment, only 8 of the 64
nodes are powered at any given time. Furthermore, only one
numerical value and only one particular letter is associated with a
powered TIR X-switch. The switching nodes shown in FIGS. 14A and
14B may be a single or double crossbar switching nodes. In the case
of single crossbar architecture, according to one embodiment, the
routing algorithm may be summarized by the following table.
TABLE-US-00001 output element a b c d e f g h input 1 node switch
switch switch switch switch switch switch switch (TIR X-Sw) mon-1
VOA VOA VOA VOA VOA VOA VOA VOA (TIR X-Sw w/PD) 2 node VOA VOA VOA
VOA VOA VOA switch switch (TIR X-Sw) mon-2 pass pass pass pass pass
pass VOA VOA (TIR X-Sw w/PD) 3 node switch switch switch switch
switch switch VOA VOA (TIR X-Sw) mon-3 VOA VOA VOA VOA VOA VOA pass
pass (TIR X-Sw w/PD) 4 node VOA VOA VOA VOA switch switch switch
switch (TIR X-Sw) mon-4 pass pass pass pass VOA VOA VOA VOA (TIR
X-Sw w/PD) 5 node switch switch switch switch VOA VOA VOA VOA (TIR
X-Sw) mon-5 VOA VOA VOA VOA pass pass pass pass (TIR X-Sw w/PD) 6
node VOA VOA switch switch switch switch switch switch (TIR X-Sw)
mon-6 pass pass VOA VOA VOA VOA VOA VOA (TIR X-Sw w/PD) 7 node
switch switch VOA VOA VOA VOA VOA VOA (TIR X-Sw) mon-7 VOA VOA pass
pass pass pass pass pass (TIR X-Sw w/PD) 8 node switch switch
switch switch switch switch switch switch (TIR X-Sw) mon-8 VOA VOA
VOA VOA VOA VOA VOA VOA (TIR X-Sw w/PD)
[0087] In the case of double crossbar architecture, the routing
algorithm gives whether the two switches of a particular switching
node (e.g., subnode-A and subnode-B) should operate as a 2.times.2
switch or as a 2.times.2 switch with variable optical attenuation,
and whether the monitor 1.times.2 switch should simply pass the
signal to the photodetector or perform as a 1.times.2 switch with
variable optical attenuation. In one embodiment, the routing
algorithm may be summarized by the following table.
TABLE-US-00002 output element a b c d e f g h input 1 first switch
(TIR X-Sw) switch switch switch switch switch switch switch switch
second switch (TIR X-Sw) switch switch switch switch switch switch
switch switch mon-1 VOA VOA VOA VOA VOA VOA VOA VOA (TIR X-Sw w/PD)
2 first switch (TIR X-Sw) VOA VOA VOA VOA VOA VOA switch switch
second switch (TIR X-Sw) switch switch switch switch switch switch
switch switch mon-2 pass pass pass pass pass pass VOA VOA (TIR X-Sw
w/PD) 3 first switch (TIR X-Sw) switch switch switch switch switch
switch VOA VOA second switch (TIR X-Sw) switch switch switch switch
switch switch switch switch mon-3 VOA VOA VOA VOA VOA VOA pass pass
(TRI X-Sw w/PD) 4 first switch (TIR X-Sw) VOA VOA VOA VOA switch
switch switch switch second switch (TIR X-Sw) switch switch switch
switch switch switch switch switch mon-4 pass pass pass pass VOA
VOA VOA VOA (TRI X-Sw w/PD) 5 first switch (TIR X-Sw) switch switch
switch switch VOA VOA VOA VOA second switch (TIR X-Sw) switch
switch switch switch switch switch switch switch mon-5 VOA VOA VOA
VOA pass pass pass pass (TIR X-Sw w/PD) 6 first switch (TIR X-Sw)
VOA VOA switch switch switch switch switch switch second switch
(TIR X-Sw) switch switch switch switch switch switch switch switch
mon-6 pass pass VOA VOA VOA VOA VOA VOA (TIR X-Sw w/PD) 7 first
switch (TIR X-Sw) switch switch VOA VOA VOA VOA VOA VOA second
switch (TIR X-Sw) switch switch switch switch switch switch switch
switch mon-7 VOA VOA pass pass pass pass pass pass (TIR X-Sw w/PD)
8 first switch (TIR X-Sw) switch switch switch switch switch switch
switch switch second switch (TIR X-Sw) switch switch switch switch
switch switch switch switch mon-8 VOA VOA VOA VOA VOA VOA VOA VOA
(TIR X-Sw w/PD)
[0088] Note that the algorithms shown in the above tables are also
valid for the various cases where TIR X-switches are selectively
replaced or completely replaced with TIR Y-switches. Even the TIR
X-switches used to make the power monitor (e.g., mon-1) may be
replaced with TIR Y-switches. The detailed optical properties such
as optical loss, crosstalk, switching characteristics and the
performance of the power monitors may be different between the
cases of using TIR X-switches and TIR Y-switches. Other
configurations may be implemented.
[0089] Also, note that an exemplary switch matrix is not limited to
a specific structure shown in an individual figure described above.
It will be appreciated that an exemplary switch matrix may be
implemented individually or in a combination of one or more
characteristics and/or configurations described above. Further, the
layout of the individual components, such as, for example, the
switching elements, input and output waveguides, optical mirrors,
waveguide bends, and/or photonic detectors, within each of the
structures shown and described above are for illustration purposes
only. Other layouts and/or more or less components may be combined
to implement an optical switch matrix using the aforementioned
techniques.
[0090] Thus, an optical switch matrix has been described. In the
foregoing specification, the invention has been described with
reference to specific exemplary embodiments thereof. It will be
evident that various modifications may be made thereto without
departing from the broader spirit and scope of the invention as set
forth in the following claims. The specification and drawings are,
accordingly, to be regarded in an illustrative sense rather than a
restrictive sense.
* * * * *