U.S. patent application number 13/012712 was filed with the patent office on 2012-07-05 for core-selective optical switches.
Invention is credited to Christopher Doerr, Peter Winzer.
Application Number | 20120170933 13/012712 |
Document ID | / |
Family ID | 46380542 |
Filed Date | 2012-07-05 |
United States Patent
Application |
20120170933 |
Kind Code |
A1 |
Doerr; Christopher ; et
al. |
July 5, 2012 |
CORE-SELECTIVE OPTICAL SWITCHES
Abstract
An optical device includes a substrate with first and second
arrays of optical couplers located along a planar surface thereof.
The optical couplers of the first array are laterally arranged
along the surface to end-couple in a one-to-one manner to
corresponding optical cores of a first multi-core fiber whose end
is facing and adjacent to the first array. The optical couplers of
the second array of optical couplers are laterally arranged along
the surface to end-couple in a one-to-one manner to corresponding
optical fiber cores of one or more optical fiber ends facing and
adjacent to the second array. An optical switch network is
optically connected to selectively couple some of the optical
couplers of the first array to the optical couplers of the second
array in a one-to-one manner.
Inventors: |
Doerr; Christopher;
(Middletown, NJ) ; Winzer; Peter; (Aberdeen,
NJ) |
Family ID: |
46380542 |
Appl. No.: |
13/012712 |
Filed: |
January 24, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61428154 |
Dec 29, 2010 |
|
|
|
Current U.S.
Class: |
398/48 ; 29/428;
385/17 |
Current CPC
Class: |
G02B 6/4249 20130101;
H01S 3/094019 20130101; H01S 3/302 20130101; H01S 3/1608 20130101;
G02B 6/4204 20130101; Y10T 29/49826 20150115; G02B 6/02042
20130101; H01S 3/0637 20130101; H01S 3/06737 20130101 |
Class at
Publication: |
398/48 ; 385/17;
29/428 |
International
Class: |
H04J 14/02 20060101
H04J014/02; B23P 11/00 20060101 B23P011/00; G02B 6/26 20060101
G02B006/26 |
Claims
1. An optical device, comprising: a substrate having a planar
surface; a first array of optical couplers located along the
surface, the optical couplers of the first array being laterally
arranged along the surface to end-couple in a one-to-one manner to
corresponding optical cores of a first multi-core fiber whose end
is facing and adjacent to the first array; a second array of
optical couplers located along the surface, the optical couplers of
the second array being laterally arranged along the surface to
end-couple in a one-to-one manner to corresponding optical fiber
cores of one or more optical fiber ends facing and adjacent to the
second array; and an optical switch network optically connected to
selectively couple some of the optical couplers of the first array
to the optical couplers of the second array in a one-to-one
manner.
2. The optical device recited in claim 1, wherein the optical
couplers of the second array are laterally arranged along the
surface to end-couple in a one-to-one manner to corresponding
optical cores of a second multi-core fiber whose end is facing and
adjacent to the second array.
3. The optical device recited in claim 2, wherein said first and
second arrays of optical couplers each include N optical couplers,
and said optical switch network comprises an array of Mach-Zehnder
interferometer switches configured to implement N.times.N
switching.
4. The optical device recited in claim 2, wherein said first and
second arrays of optical couplers each include N optical couplers,
and said switch network comprises an N.times.N Clos network or an
N.times.N Benes network.
5. The optical device recited in claim 2, wherein said switch
network includes separate first and second optical switching
networks, said first optical switching network being connected to
receive light of a linear polarity from one of the optical couplers
of the first array that is orthogonal to a linear polarity of light
that the second switching network is connected to receive from the
same one of the optical couplers of the first array.
6. The optical device recited in claim 1, further comprising a
plurality of single core optical fibers, and wherein said optical
couplers of the second array are located to couple light to
corresponding ones of the single core fibers.
7. The optical device recited in claim 1, further comprising: a
multi-core optical fiber having an end facing and adjacent to the
first array to end-couple optical cores of said multi-core optical
fiber to corresponding ones of the optical couplers of the first
array.
8. The optical device recited in claim 3, further comprising a
multi-core optical fiber having an end facing and adjacent to the
second array to end-couple optical cores of said multi-core optical
fiber to corresponding ones of the optical couplers of the second
array.
9. The optical device recited in claim 1, wherein an optical path
between said first and second plurality of couplers includes a
wavelength add/drop multiplexer.
10. The optical device recited in claim 2, further comprising a
first demultiplexer configured to separate optical wavelength
channels from a first WDM signal and a second demultiplexer
configured to separate optical wavelength channels from a second
WDM signal, wherein said switch network has first and second sets
of optical ports, the first optical ports connecting to
corresponding outputs of the first optical demultiplexer and the
second optical ports connecting to corresponding outputs of the
second optical demultiplexer.
11. The optical device recited in claim 2, further comprising a
first multiplexer configured to combine optical wavelength channels
to a first WDM signal and a second multiplexer configured to
combine optical wavelength channels to a second WDM signal, wherein
said switch network has first and second sets of optical ports, the
first optical ports connecting to corresponding inputs of the first
optical multiplexer and the second optical ports connecting to
corresponding inputs of the second optical multiplexer.
12. A method, comprising: forming a first planar array of optical
couplers along a surface of a substrate, the optical couplers of
the first array being located to couple in a one-to-one manner to
corresponding optical cores of a first multi-core fiber whose end
is facing and adjacent to the first array; forming a second planar
array of optical couplers on the planar substrate, the optical
couplers of the second array being located to couple in a
one-to-one manner to corresponding optical fiber cores of one or
more optical fiber ends facing and adjacent to the second array;
and forming an optical switch network on the substrate such that
optical ports of the switch array connect in a one-to-one manner to
the optical couplers of the first array and optical ports of the
switch array connect in a one-to-one manner to the optical couplers
of the second array.
13. The method recited in claim 12, wherein the optical couplers of
the second array are laterally arranged along the surface to
end-couple in a one-to-one manner to corresponding optical cores of
a second multi-core fiber whose end is facing and adjacent to the
second array.
14. The method recited in claim 13, wherein said first and second
arrays of optical couplers each include N optical couplers, and
said optical switch network comprises an array of Mach-Zehnder
switches configured to implement N.times.N switching.
15. The method recited in claim 13, wherein said first and second
arrays of optical couplers each include N optical couplers, and
said switch network comprises an N.times.N Clos network or an
N.times.N Benes network.
16. The method recited in claim 13, wherein said switch network
includes separate first and second optical switching networks, said
first optical switching network being connected to receive light of
a linear polarity from one of the optical couplers of the first
array that is orthogonal to a linear polarity of light that the
second switching network is connected to receive from the same one
of the optical couplers of the first array.
17. The method recited in claim 12, wherein said optical couplers
of said second array are configured to couple light to a
corresponding plurality of single core fibers.
18. The method recited in claim 13, further comprising a multi-core
optical fiber having an end facing and adjacent to the second array
to end-couple optical cores of said multi-core optical fiber to
corresponding ones of the optical couplers of the second array.
19. The method recited in claim 12, wherein an optical path between
said first and second plurality of couplers includes a wavelength
add/drop multiplexer.
20. The method recited in claim 13, further comprising configuring
a first demultiplexer to separate optical wavelength channels from
a first WDM signal and configuring a second demultiplexer to
separate optical wavelength channels from a second WDM signal,
wherein said switch network has first and second sets of optical
ports, the first optical ports connecting to corresponding outputs
of the first optical demultiplexer and the second optical ports
connecting to corresponding outputs of the second optical
demultiplexer.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of provisional patent
application Ser. No. 61/428,154 to Doerr, et al., filed on Dec. 29,
2010, incorporated herein by reference. This application is related
to application Ser. No. ______ titled "Optical Amplifier for
Multi-Core Optical Fiber" by Doerr, et al. (Docket No.
809102-US-NP) filed concurrently herewith and incorporated herein
by reference in its entirety.
TECHNICAL FIELD
[0002] This application is directed, in general, to optical devices
and methods of using optical devices.
BACKGROUND
[0003] Optical multi-core fibers include several core regions,
wherein each core region is capable of propagating substantially
independent optical signals. Such fibers may provide significantly
greater data capacity than a single core fiber. Thus, multi-core
fibers enable significant increases to the rate of data transfer in
optical systems for lower cost than would be the case for one or
multiple single mode fibers.
SUMMARY
[0004] One aspect provides an optical device. The optical device
includes a substrate and first and second arrays of optical
couplers located along a planar surface thereof. The optical
couplers of the first array are laterally arranged along the
surface to end-couple in a one-to-one manner to corresponding
optical cores of a first multi-core fiber whose end is facing and
adjacent to the first array. The optical couplers of the second
array of optical couplers are laterally arranged along the surface
to end-couple in a one-to-one manner to corresponding optical fiber
cores of one or more optical fiber ends facing and adjacent to the
second array. An optical switch network is optically connected to
selectively couple some of the optical couplers of the first array
to the optical couplers of the second array in a one-to-one
manner.
[0005] Another aspect provides a method. The method includes
forming on a planar substrate surface first and second arrays of
optical couplers. The optical couplers of the first array are
laterally arranged along the surface to end-couple in a one-to-one
manner to corresponding optical cores of a first multi-core fiber
whose end is facing and adjacent to the first array. The optical
couplers of the second array of optical couplers are laterally
arranged along the surface to end-couple in a one-to-one manner to
corresponding optical fiber cores of one or more optical fiber ends
facing and adjacent to the second array. The method includes
optically connecting an optical switch network to selectively
couple some of the optical couplers of the first array to the
optical couplers of the second array in a one-to-one manner.
BRIEF DESCRIPTION
[0006] Reference is made to the following descriptions taken in
conjunction with the accompanying drawings, in which:
[0007] FIG. 1 illustrates an embodiment of an optical switch, e.g.
an example N.times.N core-selective switch;
[0008] FIG. 2 illustrates a portion of an integrated monolithic
planar array of optical couplers that may be used in the optical
switch of FIG. 1;
[0009] FIG. 3 illustrates optical coupling between a multicore
fiber (MCF) and an integrated planar optical coupler;
[0010] FIGS. 4A and 4B illustrate location and orientation features
of the coupling of a single core of an MCF to a 1-D planar grating
coupler;
[0011] FIG. 5 illustrates an embodiment of an optical switch
configured to independently switch different polarization modes of
received optical signals;
[0012] FIG. 6 illustrates an embodiment of an optical switch
configured to switch optical signals between two input MCFs and two
output MCFs;
[0013] FIG. 7 illustrates an embodiment of a polarization diverse
core-selective switch in which some grating couplers are configured
to couple to corresponding single-core fibers (SCFs);
[0014] FIGS. 8A-8C illustrate aspects of an embodiment in which an
optical switch, e.g. a Mach-Zehnder switch, is located at
intersections of waveguides;
[0015] FIGS. 9A and 9B, illustrate embodiments of Mach-Zehnder
switches that may be used in the core-selective switch of FIG.
5A;
[0016] FIGS. 10A and 10B respectively illustrate embodiments of a
Benes network and a Clos network, respectively, that may be used in
the core-selective switch of FIG. 8A;
[0017] FIG. 11 illustrates an embodiment in which a core-selective
switch, e.g. an N.times.N switch array, may be used to switch
channels of WDM signals between MCFs;
[0018] FIG. 12 illustrates a method of forming a core-selective
optical switch such as the device of FIG. 1; and
[0019] FIG. 13 illustrates an embodiment of coupling optical
signals controlled by a switch network to SMFs via edge facet
couplers.
DETAILED DESCRIPTION
[0020] Some optical multi-core fibers (MCFs) provide an integrated
optical transport medium in which each optical core can transport
an optical signal stream, simultaneously with the other optical
core(s), without causing significant optical crosstalk with optical
signal streams carried by the other optical core(s). For these
reasons, there is a potential to replace several single-core fibers
(SCFs) with a single MCF. Thus, such use of MCFs may reduce the
cost and space associated with transport media for optical signals
within an optical communications system. However, it is sometimes
necessary to access an optical signal stream carried by a single
optical core of an MCF, such as for optical processing or routing
of the optical signal stream.
[0021] One device for separately accessing an individual optical
core of an MCF fuses a fan-out of the optical cores of the MCF to
an optical waveguide fan-out section. In such a device, single
cores from the fan-out of the MCF end-connect to single optical
waveguides of the optical waveguide fan-out section. Thus, the
optical signals carried by the individual optical cores of the MCF
are transferred to corresponding individual single-core optical
fibers or optical waveguides, e.g., single-mode fibers. Once routed
to individual single-core optical fibers of optical waveguides, the
optical signals from the different optical cores may be separately
processed by optical components designed to interface to the
single-core optical fibers or optical waveguides. Nevertheless,
these devices can be expensive to fabricate, physically cumbersome,
and not easily mass-produced. The limitations of devices based on
such fan-out sections may present an impediment to the large-scale
adoption of MCFs in telecommunications architectures.
[0022] Some embodiments described herein provide the
functionalities of devices based on fan-out sections of MCFs
without an actual fan-out section therein. In particular, the
embodiments include an integrated photonic device (IPD) having one
or more integrated planar arrays of optical couplers that can
couple to individual optical cores of MCF(s).
[0023] Such IPDs may be formed on a surface of many
micro-electronics and integrated optical substrates, e.g., a
portion of a semiconductor wafer. In such IPDs, optical components
may be formed on the planar surface using conventional material
deposition and patterning processes. Such components may include,
but are not limited to, optical gratings, waveguides, couplers,
switches, lasers and photodiodes. The components of the integrated
planar array are integral to each other, e.g. cannot be separated
nondestructively and reassembled. An array of optical couplers is
considered to be "planar" when formed on an approximately planar
surface of an optical device. Such arrays may be formed, e.g. at
about a same height over a substantially planar substrate such as a
semiconductor wafer. A substantially planar substrate may be a
planar surface or a surface having a roughly planar orientation and
a surface relief patterned thereon, e.g., a relief produced by
micro-electronics deposition, growth, and/or etching
techniques.
[0024] In various embodiments of IPDs herein, the arrays of optical
couplers may be arranged to directly end-couple to the optical
cores of an MCF. The optical signals carried by the separate
optical cores of the MCF may be separately processed on the IPD
and/or may be separately coupled to single-core optical waveguides,
other MCFs or a combination thereof. The IPDs may be produced,
e.g., using conventional processing methods for micro-electronics
devices and integrated optical devices.
[0025] In various embodiments herein such coupler arrays are
integrated with optical components on an IPD substrate to provide
optical signal processing functions such as switching from one
optical path to another. Some such embodiments provide inexpensive
ways of integrating MCFs into optical communications architectures
and/or of realizing the potential of MCFs to increase the
signal-carrying capacity of optical signal transmission paths.
[0026] FIG. 1 illustrates a 1.times.1 optical device 100, e.g. a
core-selective switch for coupling seven optical cores of one MCF
to seven optical cores of another MCF. The device 100 includes a
first integrated planar array 110 of optical couplers and a second
integrated planar array 120 of optical couplers. Each of the
integrated planar arrays 110, 120 includes a plurality of optical
couplers 230, described below. As used herein, "array" excludes the
trivial case of only a single optical coupler 230. Each optical
coupler 230 of each of the integrated planar arrays 110, 120 is
configured to optically couple to a corresponding optical core of
an MCF (not shown). In various embodiments the integrated planar
arrays 110, 120 may operate to either receive data from an MCF or
to provide data to an MCF.
[0027] Each of the waveguides 130 optically couples a corresponding
one of the optical couplers 230 of the integrated planar array 110
to a port of a switch network 140. Similarly, each of the
waveguides 150 optically couples a corresponding one of the optical
couplers 230 of the integrated planar array 120 to a port of the
switch network 140. As discussed further below, the switch network
140 may provide selective switching of any one of the optical
couplers 230 of the integrated planar array 110 to any one of the
optical couplers 230 of the integrated planar array 120. When the
integrated planar arrays 110, 120 are each optically coupled to a
corresponding MCF, the switch network 140 may provide
core-selective switching from any core of one MCF to any core of
the other MCF.
[0028] In the illustrated embodiment, the switch network 140 may
switch any of seven optical cores that couple to the seven output
optical couplers 230 of the integrated planar arrays 110, 120.
However, the various embodiments are not limited to any particular
number of optical cores in the MCFs therein.
[0029] Optionally a wavelength add/drop multiplexer 160 may be
configured to add or remove one or more channels on an optical
signal propagating within one or more of the waveguides 130. The
wavelength add/drop multiplexer 160 may include, e.g., a
controllable phase adjuster 170, e.g. a heater, to control the
add/drop function. The wavelength add/drop multiplexer 160 may be
used, e.g. when the signal within the adjacent waveguide 130
propagates a wavelength-division multiplexed (WDM) signal, e.g.,
the added and/or dropped channel(s) may be selected wavelength
channel(s).
[0030] FIG. 2 illustrates a single coupler array, e.g. the
integrated planar array 110 or the integrated planar array 120. The
illustrated single coupler array includes segments of the seven
optical waveguides 130. In the coupler array, each optical
waveguide segment may include an optical coupling segment 210 and a
transition segment 220. Each optical coupling segment 210 has an
optical coupler 230 located thereon or therein. The optical coupler
230 is laterally positioned to optically end-couple a single
corresponding optical core of an MCF (not shown). The optical
coupling segments 210 may be customized to enhance their couplings
to the optical cores of an MCF via the corresponding optical
couplers 230, e.g., each optical coupling segment 210 may be wider
than the remainder of the corresponding optical waveguide. Each
transition segment 220 provides a coupler between the optical
coupling segment 210 and the communication segment (shown to the
right in FIG. 2) of the same waveguide. The transition segment 220
may be configured to reduce coupling/insertion losses between the
differently sized coupling and communication segments of the same
optical waveguide.
[0031] Examples of some grating couplers that may be suitable for
use as the optical couplers 230 may be described, e.g., in U.S.
patent application Ser. No. 12/972,667 (the '667 Application) to
Christopher Doerr, incorporated herein by reference in its
entirety.
[0032] The optical couplers 230 are often arranged in a lateral
pattern that corresponds in form and size to a lateral pattern of
optical cores within an MCF whose end would approximately face and
be adjacent to the optical coupler, e.g., as discussed in the '667
application. In the illustrated embodiment, the example coupler
array of FIG. 2 is configured to couple to seven optical cores
arranged at corners and the center of a regular hexagon. However,
embodiments are not limited to such an arrangement of optical cores
in the MCF or to a particular number of cores in the MCF.
[0033] FIG. 3 illustrates a perspective view of a coupler array,
e.g. the integrated planar array 110, located along a planar
surface of a substrate 310. An MCF 320 has an end located over the
coupler array and is rotationally aligned so that the individual
optical cores of the MCF 320 face and optically couple to
corresponding individual ones of the optical couplers of the
integrated planar array 110. For example, each optical core 330 may
be positioned and oriented to be able to project a light spot 360
onto a single one of the optical couplers of the integrated planar
array 110 without projecting light onto other optical couplers
thereof. Additional details of coupling between the MCF 320 and the
integrated planar array 110 are provided in the '667
Application.
[0034] FIGS. 4A and 4B illustrate orientational and locational
aspects of the coupling of the optical signal 340 to one of the
optical couplers 230, e.g. a 1-D array of gratings. The projected
light spot 360 produces an approximate Gaussian distribution 410
located over the corresponding optical coupler 230 with sufficient
overlap to couple light from the optical signal 340 to the optical
coupling segment 210.
[0035] In the illustrated embodiment the optical core 330 of the
MCF makes an angle with respect the surface normal of the optical
coupling segment 210 to produce a polarization-separating optical
coupler. At a particular angle .phi. determined in part by the
wavelength of the optical signal 340, a TE polarization mode 420 of
the optical signal 340 may couple to the optical coupling segment
210 with a propagation direction to the right as FIG. 4B is
oriented. Similarly, a TM polarization mode 430 of the optical
signal 340 may couple to the optical coupling segment 210 with a
propagation direction to the left as FIG. 4B is oriented. Such
coupling of TE and TM polarization modes may be used to form
polarization-diverse embodiments of core-selective switches, as
described further below. Additional information regarding such
polarization splitting may be found in Yongbo Tang, et al.,
"Proposal for a Grating Waveguide Serving as Both a Polarization
Splitter and an Efficient Coupler for Silicon-on-Insulator
Nanophotonic Circuits", IEEE Photonics Technology Letters, Vol. 21,
No. 4, pp 242-44, Feb. 15, 2009, incorporated herein by reference
in its entirety.
[0036] FIG. 13 illustrates a portion of an embodiment in which
conventional edge facet couplers 1310 conventionally couple one or
more of the optical waveguides connected to the switch network 140.
Planar waveguides 1320 are representative of any of the waveguides
130, 150 of FIG. 1. The waveguides 1320 terminate at edge facets
1330 located at or near an edge of a substrate 1340. Single core
fibers 1350 are located such that fiber cores 1360 optically
end-couple to the edge facets 1330 such that optical signals may
propagate therebetween. An edge facet coupler may be used to
end-couple an optical fiber to the switch network 140 of FIG. 1.
Additional embodiments of edge facet couplers that may be used with
embodiments of this disclosure may be found in U.S. Patent
Application No. 2011/xxx,xxx titled "Multi-Core Optical Cable to
Photonic Circuit Coupler" by Doerr, et al. (Docket No.
809103-US-CIP), filed concurrently herewith and incorporated herein
by reference in its entirety.
[0037] FIG. 5 illustrates another 1.times.1 optical device 500,
i.e., a core-selective switch for coupling one MCF to another MCF.
In addition to those components described in FIG. 1, the device 500
includes a switch network 510 and optical waveguides 520, 530. The
optical waveguides 520 couple optical couplers 230 of the
integrated planar array 110 to the switch network 510, and the
optical waveguides 530 couple optical couplers 230 of the
integrated planar array 120 to the switch network 140.
[0038] The operation of the optical device 500 is described with
respect to an example configuration in which the integrated planar
array 110 receives optical signals from an input MCF, and the
integrated planar array 120 provides received optical signals to an
output MCF. As described above, the optical couplers 230 of the
integrated planar array 110 couple TE and TM polarized light from
the received signals in opposite directions. Thus, TE components of
optical signals received from an MCF by the integrated planar array
110 propagate to the right via the waveguides 130, and TM
components thereof propagate to the left via the optical waveguides
520. The switch network 140 receives the TE components, while the
switch network 510 receives the TM components. The switch networks
140, 510 separately switch, e.g., the TE and TM components of
received optical signals from the optical couplers 230 of the
integrated planar array 110 and the optical couplers 230 of the
integrated planar array 120, e.g., in any routing combinations.
[0039] In some embodiments of the optical device 500 of FIG. 5,
routing via the two switch networks 140 and 510 may be coordinated
such that associated TE and TM components of light received via a
particular input optical coupler 230 are routed to a same output
optical coupler 230. In such cases the optical device 500 operates,
e.g. as a polarization-diverse core-selective switch, because the
routed optical intensity is substantially independent of the
polarization of the received light.
[0040] In other embodiments, the TE and TM components of light
received from the same input optical coupler 230 may be routed
differently by the two switch networks 140 and 510, i.e., routed to
different output optical couplers 230. In such embodiments, the
optical device 500 functions as a polarization-dependent switch,
which may be used, e.g., in dual-polarization optical transmitters,
routers, and/or receivers.
[0041] FIG. 6 illustrates an embodiment of a 2.times.2 optical
device 600, i.e., a core-selective optical switch. The optical
device 600 has first and second integrated planar arrays 110-1,
110-2 that may operate, e.g., to receive optical signals from first
and second input MCFs and has first and second integrated planar
arrays 120-1, 120-2 that may operate to transmit the received
optical signals to first and second output MCFs in an optical
core-selective manner.
[0042] The first and second integrated planar arrays 110-1, 110-2
are configured to end-couple to the ends of the first and second
input MCFs (not shown). The first and second integrated planar
arrays 120-1, 120-2 are configured to end-couple to the ends of the
first and second output MCFs (not shown). Optical waveguides 610
connect the optical couplers 230 of the first and second integrated
planar arrays 110-1, 110-2 to a switch network 620. Optical
waveguides 630 connect the optical couplers 230 of the first and
second integrated planar arrays 120-1, 120-2 to the switch network
620. Similarly, optical waveguides 640 connect the optical couplers
230 of the first and second integrated planar arrays 110-1, 110-2
to a switch network 660, and optical waveguides 650 connect the
optical couplers 230 of the first and second integrated planar
arrays 120-1, 120-2 to the switch network 660.
[0043] The switch network 620 may be able, e.g., to route the TE
component light signals received by any one of the optical couplers
230 of the first and second integrated planar arrays 110-1, 110-2
to any one of the optical couplers 230 of the first and second
integrated planar arrays 120-1, 120-2. Similarly, the switch
network 660 may be able, e.g., to route the TM component light
signals received by any one of the optical couplers 230 of the
first and second integrated planar arrays 110-1, 110-2 to any one
of the optical couplers 230 of the first and second integrated
planar arrays 120-1, 120-2. Thus, the optical device 600 may switch
an optical signal received via an optical core of an input MCF to
any optical core of a plurality of output MCFs. In some
embodiments, the switch networks 620 and 660 perform correlated
routing so that the 2.times.2 optical device 600 is polarization
diverse. In other embodiments, the switch networks 620 and 660
perform separate routing of received TM and TE light so that the
2.times.2 optical device 600 is optical core selective and
polarization selective.
[0044] FIG. 7 illustrates an embodiment of an optical device 700
for coupling two MCFs to an MCF and another MCF or a set of
single-core fibers (SCFs). The basis of operation of the optical
device 700 is as described, e.g. for the optical device 600. In the
illustrated embodiment, however, the integrated planar array 110-1
is replaced with an SCF coupler 710 for each optical coupler 230 in
the integrated planar array 110-1. In some embodiments of the
optical device 700, the SCF couplers 710 are placed with sufficient
distance from each other that the end of a SCF may be located over
each of the SCF couplers 710 simultaneously. In such embodiments,
the optical device 700 may switch an optical signal between any one
of the SCF couplers 710 and any one of the optical couplers 230 of
the integrated planar arrays 120-1, 120-2. Thus, the optical device
700 may provide fan-in of multiple SCFs to one or more MCFs by a
single, compact IPD.
[0045] FIGS. 8A-8C illustrate aspects of one embodiment of a switch
network 800 that may be used, e.g. as the switch networks 140, 510,
620, and 660 of FIGS. 1 and 5-7. The switch network 800 includes N
input/output ports 801 and N output/input ports 802, where e.g.
N=7. An N.times.N array of 2.times.2 switches 810 (FIG. 8B) couples
the input/output ports 801 and the output/input ports 802, e.g., in
a one-to-one manner. In the illustrated embodiment, the
input/output ports 801 may receive or provide optical signals
from/to the waveguides 150, and the output/input ports 802 may
provide or receive optical signals to/from the waveguides 130. The
array of switches 810 may provide N.times.N switching of signals
propagated by the waveguides 130 and the signals propagated by the
waveguides 150. Herein, an N.times.N array of switches 810 may
connect the input/output ports 801 to the output/input ports 802 in
a one-to-one manner.
[0046] Each embodiment of the 2.times.2 switch 810 is located at an
intersection of a vertical waveguide 820 (FIG. 8B) and a horizontal
waveguide 830. In one embodiment the 2.times.2 switch 810 is a
2.times.2 Mach-Zehnder interferometer (MZI). FIG. 9A illustrates an
embodiment in which the 2.times.2 switch 810 comprises an MZI
switch 905. In the 2.times.2 MZI, a 2.times.2 input optical coupler
910 couples two input waveguides 915, 920 to two internal optical
waveguides. In the 2.times.2 MZI, a 2.times.2 output coupler 925
couples the two internal optical waveguides to two output
waveguides 930, 935. In the (MZI) 940, one of the two internal
optical waveguides has an optical path length that is controllable,
e.g. by an optical phase shifter electrically controlled via a
control 945. As appreciated by those skilled in the optical arts,
suitably controlling the relative phase of the optical paths of the
MZI 940 can switch light received by one of the input waveguides
915, 920 to either selected one of the output waveguides 930, 935.
Multiple, e.g. N.sup.2, instances of the of the 2.times.2 MZI
switch 905 may provide the individual switches for performing the
routing between the N input/output ports 801 and the N output/input
ports 802 of the switch network 800.
[0047] FIG. 9B illustrates an embodiment in which the switch 810
includes four MZI switches 905 cross-coupled as illustrated. Each
MZI switch 905 is configured such that one input waveguide 915, 920
or one output waveguide 930, 935 is unused. Thus two instances of
the MZI switch 905 have only one input, and two instances of the
MZI switch 905 have only one output. The embodiment of FIG. 9B may,
e.g. provide better isolation between the optical signals received
by the switch 810.
[0048] Returning to FIG. 8C, illustrated is an embodiment in which
more than one switch 810 may be operated simultaneously to effect
splitting of an optical signal. For example, an optical signal
received on the vertical waveguide 820 may be split between the
horizontal waveguide 830 and another horizontal waveguide 850 by
simultaneously partially operating the switch 810 and a switch 840.
Each switch 810, 840 may include, e.g. a 2.times.2 MZI switch 905.
The 2.times.2 MZI switch 905 may be operated such that a portion of
the optical power received at one of the input waveguides 915, 920
is routed to each of the output waveguides 930, 935. The switch 810
may thus be operated, e.g. such that less than all the optical
power received thereby from the vertical waveguide 820 is directed
to the horizontal waveguide 830. The switch 840 may be operated
such that all the remaining optical signal power is directed to the
horizontal waveguide 850. In some embodiments the switch 840
directs only a portion of the power received thereby to the
horizontal waveguide 850, with the remaining portion directed to
another switch.
[0049] In some embodiments, the switch networks 140, 510, 620, and
660 may have other constructions than networks of interconnected
MZIs. For example, the switch networks 140, 510, 620, and 660 may
include a Benes network 1010 as illustrated in FIG. 10A or a Clos
network 1020 as illustrated in FIG. 10B or a fan-out-and-select
network (not shown) may be used. Further information on Benes and
Clos networks may be respectively found in, e.g. Guido Maier, et
al., "Optical-Switch Benes Architecture based on 2-D MEMS", 2006
Workshop on High Performance Switching and Routing (IEEE), pp. 6,
doi: 10.1109/HPSR.2006.1709718, and U.S. Pat. No. 6,696,917 to
Heitner, et al. Each of the networks 1010, 1020 is an N.times.N
network, and includes N inputs and N outputs, where N equals, e.g.
seven. In another embodiment the switch networks 140, 510, 620, and
660 include a fanout-and-select architecture. In this architecture,
a tree arrangement of 1.times.2 switches branches N input ports to
N.sup.2 waveguides and then a tree arrangement of 2.times.1
switches connects the N.sup.2 waveguides to N output ports. In some
embodiments switches may include the use of
micro-electrical-mechanical (MEM) devices such as individually
actuated micromirrors to provide for reconfigurable optical routing
via free space devices rather than integrated optical devices.
[0050] FIG. 11 schematically illustrates an embodiment of an IPD
1100 in which a switch network 1105 may be used to effect
wavelength-selective switching of individual channels of a WDM
signal between optical couplers 1125, 1130, 1170, 1175. First and
second fiber cores 1107, 1110 provide N, e.g. first and second
input WDM signals 1115, 1120. In various embodiments, the fiber
cores 1107, 1110 may be optical cores from a single MCF or
different optical fibers. In some embodiments at least one of the
fiber cores 1107, 1110 is a core from an SCF.
[0051] The first input WDM signal 1115 includes m channels, e.g.
with wavelengths .lamda..sub.11, .lamda..sub.12, .lamda..sub.13,
.lamda..sub.14. The second input WDM signal 1120 also includes m
channels, e.g. with wavelengths .lamda..sub.21, .lamda..sub.22,
.lamda..sub.23, .lamda..sub.24. In other embodiments, the number of
channels provided by the WDM signal 1115 may be different than the
number of channels provided by the WDM signal 1120. Optical
couplers 1125, 1130, e.g. such as those described by the optical
coupler 230, couple the WDM signals 1115, 1120 to respective first
and second demultiplexers 1135, 1137. The demultiplexer 1135
separates a first WDM input channel set 1140, and the demultiplexer
1137 separates a second WDM input channel set 1142. In some
embodiments an add/drop multiplexer 1143 may be used to remove one
or more wavelength-channels from and/or add one or more
wavelength-channels to, the set(s) of wavelength channels of the
WDM signals 1115, 1120.
[0052] The switch network 1105 receives the input
wavelength-channel sets 1140, 1142 at m*N inputs. The switch
network 1105 provides output wavelength-channel sets 1147, 1155 at
m*N outputs. In some embodiments the switch network 1105 may be
controlled to switch any of the wavelength-channels of the first
input channel set 1140 with any of the wavelength-channels of the
second input channel set 1142. Thus, as in the illustrated example,
the .lamda..sub.12 channel is grouped with .lamda..sub.21,
.lamda..sub.23, .lamda..sub.24 channels in the channel group 1155,
and the .lamda..sub.22 channel is grouped with .lamda..sub.11,
channels in the channel group 1147. In various embodiments, WDM
wavelength-channels at a particular wavelength, e.g. .lamda..sub.12
and .lamda..sub.22, may be swapped among two or more output cores
so that no WDM wavelength-channels are superimposed onto a same
output core, as in the illustrated embodiment.
[0053] A first multiplexer 1145 combines the first output
wavelength-channel set 1147 to produce a first output WDM signal
1150. A second multiplexer 1160 combines the second output
wavelength-channel set 1155 to produce a second output WDM signal
1165. The first and second output optical couplers 1170, 1175
respectively couple the output WDM signals 1150, 1165 to first and
second output fiber cores 1180, 1185. In various embodiments the
fiber cores 1180, 1185 may be optical cores from a same MCF or
optical cores of different optical fibers. In some embodiments at
least one of the fiber cores 1180, 1185 is a core from an SCF.
[0054] FIG. 12 illustrates a method 1200 for forming an optical
device, e.g., the optical devices 100, 500, 600, and 700 of FIGS.
1, 5, 6, and 7. The method 1200 will be described without
limitation by making exemplary references to the various
embodiments described herein, e.g. by FIGS. 1-11. The steps of the
method 1200 may be performed in an order other than the illustrated
order.
[0055] A step 1210 includes forming a first integrated planar array
of optical couplers, e.g. the integrated planar array 110, having a
first plurality of optical couplers, e.g. instances of the optical
coupler 230. The optical couplers of the first plurality are
configured to couple a corresponding plurality of optical signals
to a first plurality of optical cores of a first multi-core fiber,
e.g. the MCF 320.
[0056] A step 1220 includes forming a second integrated planar
array of optical couplers, e.g. the integrated planar array 120,
having a second plurality of optical couplers, e.g. instances of
the optical coupler 230. The optical couplers of the second array
are configured to couple the plurality of optical signals to a
second plurality of optical cores, e.g., of the MCF 320.
[0057] A step 1230 includes forming a switch network that is able
to optically couple in a one-to-one manner optical couplers of the
first plurality of optical couplers to optical couplers of the
second plurality of optical couplers.
[0058] The following provides various optional features of the
method 1200. In some cases these optional features may be
combined.
[0059] The optical couplers of the second array may be laterally
arranged along the substrate surface to end-couple in a one-to-one
manner to corresponding optical cores of a second multi-core fiber
whose end is facing and adjacent to the second array. The first and
second pluralities of optical couplers may each include N optical
couplers. The switch network may include an array of 2.times.2
Mach-Zehnder interferometers configured to implement N.times.N
switching. The first and second pluralities of optical couplers may
each include N optical couplers, and the switch network may
comprise an N.times.N Clos network or an N.times.N Benes
network.
[0060] The switch network may include a first switch network
connected to switch a first polarization mode of received optical
signals and a second switch network connected to switch a second
polarization mode of the received optical signals.
[0061] The second plurality of optical couplers may include grating
couplers configured to couple light to a corresponding plurality of
single core fibers.
[0062] The couplers of the second plurality of optical couplers may
include edge facet couplers.
[0063] An optical path between the first and second plurality of
the optical couplers may include an add/drop multiplexer.
[0064] Each of the first plurality of optical couplers may be
coupled to a corresponding optical core of a multi-core optical
fiber.
[0065] The switch network may include separate first and second
optical switching networks. The first optical switching network may
be connected to receive light of a linear polarity from one of the
optical couplers of the first array that is orthogonal to a linear
polarity of light that the second switching network is connected to
receive from the same one of the optical couplers of the first
array.
[0066] The optical couplers of the second array may be configured
to couple light to a corresponding plurality of single core
fibers.
[0067] The optical device may further include a multi-core optical
fiber having an end facing and adjacent to the second array to
end-couple optical cores of said multi-core optical fiber to
corresponding ones of the optical couplers of the second array.
[0068] An optical path between said first and second plurality of
couplers may include an add/drop multiplexer.
[0069] A first demultiplexer may be configured to separate optical
wavelength channels from a first WDM signal. A second demultiplexer
may be configured to separate optical wavelength channels from a
second WDM signal. First optical ports of the switch network may
connect to corresponding outputs of the first optical
demultiplexer, and the second optical ports of the switch network
may connect to corresponding outputs of the second optical
demultiplexer.
[0070] First and second multiplexers may be configured such that
the first multiplexer is configured to combine optical wavelength
channels to a first WDM signal, and the second multiplexer is
configured to combine optical wavelength channels to a second WDM
signal. The inputs of the first optical multiplexer may be
connected to a first set of optical ports of the switch network.
The inputs of the second optical multiplexer may be connected to a
second set of optical ports of the switch network.
[0071] Those skilled in the art to which this application relates
will appreciate that other and further additions, deletions,
substitutions and modifications may be made to the described
embodiments.
* * * * *