This application is related to U.S. Patent
Application No. 13/538,525 (the 525 Application) filed
on June 29, 2012 and incorporated by reference herein.
This application is further related to U.S. Patent
Application No. 13/800,403 {Attorney Docket Number
812258-US-NP) (the '258 Application") filed on even date
herewith and incorporated by reference herein. The
present application claims the benefit to the previously
filed U.S. Provisional Patent Application No. 61/667,374
also of the same title, filed July 2 , 2012, and which is
incorporated herein by reference in its entirety. The
present application further claims the benefit to the
previously filed U.S. Provisional Patent Application No.
61/667,380 (the 380 Application) of the same title,
filed July 2 , 2012, and which is incorporated herein by
reference in its entirety.
TECHNICAL FIELD
This application is directed, in general, to optical
communications systems and methods.
BACKGROUND
This section introduces aspects that may be helpful
to facilitating a better understanding of the inventions.
Accordingly, the statements of this section are to be
read in this light and are not to be understood as
admissions about what is in the prior art or what is not
in the prior art.
Optical switching networks employ a switching
topology that may be referred to as an "optical switch
fabric." A s the size and speed of such networks grows,
new optical switch fabrics that provide greater
capability are needed to keep pace with such growth. One
aspect of capability to be addressed is configuration of
such optical networks.
BRIEF SUMMARY OF ILLUSTRATIVE EMBODIMENTS
One aspect provides a system, e.g. a reconf igurable
optical channel router. The system includes an input
waveguide optically connected to a wavelength
demultiplexer and configured to propagate a plurality of
wavelength channels of an optical carrier signal. A first
input microcavity resonator set is located adjacent the
input waveguide. The set includes a plurality of
microcavity resonators that are each configured to
controllably couple to a corresponding one of a plurality
of frequency channels of an optical signal propagating
within the input waveguide.
Another aspect provides a method, e.g. for forming
an optical system, e.g. a reconf igurable optical channel
router. The method includes forming an input waveguide
optically connected to a wavelength demultiplexer.
Microcavity resonators of a first input set of
microcavity resonators are formed located adjacent the
input waveguide. Each microcavity resonator is configured
to controllably couple to a corresponding one of a
plurality of frequency channels propagating within the
input waveguide .
Yet another aspect provides a method, e.g. for
forming an optical system, e.g. a reconf igurable optical
router. In a first step of the method a first substrate
is provided. The first substrate has an input waveguide
optically connected to a wavelength demultiplexer. A
first input microcavity resonator set including a
plurality of microcavity resonators located adjacent the
input waveguide. The microcavity resonator set includes a
plurality of microcavity resonators, each being
configured to couple to a different frequency channel of
an optical signal propagating within the input waveguide .
In a second step of the method a second substrate is
provided. The second substrate has an electronic
controller formed thereover. The controller is configured
to control each of the microcavity resonators to
controllably couple to a corresponding one of the
frequency channels. In a third step of the method the
first and second substrates are joined, thereby operably
connecting the controller to the microcavity resonators.
In any embodiment a plurality of output waveguides
may be formed, each waveguide being optically connected
to the wavelength demultiplexer. In such embodiments the
wavelength demultiplexer may be configured to route each
carrier signal to a corresponding one of the output
waveguides . Any embodiment may include forming a
plurality of output microcavity resonator sets. Each
resonator set includes a corresponding plurality of
microcavity resonators. Each microcavity resonator of
each output set is located adjacent a same corresponding
one of the output waveguides such that the microcavity
resonators of each output set may controllably couple to
a corresponding different wavelength channel propagating
within the corresponding output waveguide.
In some such embodiments a plurality of optoelectric
transducers may be formed, with each of the transducers
being optically coupled to a corresponding one of the
output microcavity resonators. Each transducer is
configured to convert an optical signal within its
corresponding resonator to an electrical signal.
In any embodiment the wavelength demultiplexer may
include an arrayed waveguide grating (AWG) . In any
embodiment the AWG may be configured to provide cyclic
permutations of optical paths of the wavelength channels
between inputs and outputs of the A G . In any embodiment
the waveguide and wavelength demultiplexer may be formed
from silicon. Any embodiment may include control
electronics configured to modulate a resonant frequency
of the microcavity resonators. In any embodiment the
microcavity resonators may be ring resonators.
One embodiment is a system comprising a first
plurality of separate sets of optical ring resonators, a
second plurality of separate sets of optical ring
resonators, and an optical multiplexer/demultiplexer. The
optical multiplexer/demultiplexer has a set of optical
inputs and a set of optical outputs. Each set of the
first plurality of separate sets is optically connected
to a corresponding one of the optical inputs of the
optical multiplexer/demultiplexer. Each set of the
second plurality of separate sets is optically connected
to a corresponding one of the optical outputs of the
optical multiplexer/ demultiplexer .
Some such embodiments further comprise a plurality
of first devices, each first device being connected to
modulate digital data streams onto optical carriers via
the ring resonators of a corresponding one of the sets of
the first plurality. Some such embodiments further
:omprise a plurality of first apparatuses, each first
apparatus being connected to demodulate digital data
streams from optical carriers via the ring resonators of
a corresponding one of the sets of the second plurality.
Some such embodiments further comprise a plurality of
first apparatuses, each first apparatus being connected
to demodulate digital data streams from optical carriers
via the ring resonators of a corresponding one of the
sets of the second plurality. Some such embodiments
further comprise an electronic controller capable of
separately adjusting resonant frequencies of some of the
ring resonators of the sets of the first plurality. Some
such embodiments further comprise a plurality of first
optical fibers, each first optical fiber connecting a
corresponding one of the sets of the first plurality to a
multi-wavelength channel optical source. In some such
embodiments each first optical fiber connects to a
corresponding one of the optical inputs of the optical
multiplexer/ demultiplexer .
BRIEF DESCRIPTION
Reference is now made to the following descriptions
taken in conjunction with the accompanying drawings, in
which :
FIG. 1 illustrates a system, e.g. an MxN
reconf igurable optical network according to one
embodiment, that provides optical domain switching of
received wavelength channels of wavelength division
multiplexed (WDM) signals;
FIG. 1A schematically illustrates operation of the
optical network of FIG. 1 in a nonlimiting embodiments to
optically provide data connections between input
electrical devices and output electrical devices;
FIG. 2 illustrates aspects of a frequency comb
including a number of wavelength channels;
FIG. 3 illustrates an opto-electric domain converter
used in various embodiments to convert a modulated
optical signal to the electrical domain;
FIGs. 4A-4C illustrate signal routing in one
illustrative embodiment by an arrayed waveguide grating
that may be used in a switching stage of the system of
FIG. 1 ;
FIG. 5A-5C illustrate various embodiments in which
portions of the system are formed on separate substrates
that are joined to form the system, e.g. the system of
FIG. 1 ; and
FIG. 6 presents a f ow diagram of a method, e.g. for
forming a system, e.g. the system of FIG. 1 , according to
various embodiments; and
FIG. 7 presents a flow diagram of a method, e.g. for
forming a system, e.g. the system of FIG. 1 , according to
various embodiments .
DETAILED DESCRIPTION
The inventors believe that a compact and flexible
architecture for switching data in an optical network may
be implemented using microcavity resonators coupled to
waveguides to, e.g. selectively add and drop modulated
optical signals within an opto-electric switching matrix.
Embodiments may be used to provide compact and low-cost
signal routing at a small scale, e.g. within a photonic
integrated circuit, a medium scale, e.g. within a data
center, or large-scale, e.g. long-haul optical
communication system.
Some structures and/or methods described in 380
Application, and/or the 258 Application, may be suitable
for making or using similar structures and/or methods of
the present application.
FIG. 1 presents a system 100, e.g. an embodiment of
an MNxNM reconf igurable electrical cross-connect 100. The
cross-connect 100 uses optical wavelength channels to
selectively route digital data signal streams between M
electrical ports of N output devices to N ports of M
input devices in a one-to-one manner with respect to
individual ports of the input and output devices. The
individual input ports are indexed by a pair of integers
{m, n ) , i.e., m = 1 , 2 , ... M and n = 1 , 2 , ... , and the
individual output ports are indexed by a pair of integers
(n, ) , i.e., n = 1 , 2 , ... N and = 1 , 2 , ... M . The
parameter N describes a number o f wavelength division
multiplexed (WDM) carriers available to transmit data.
The system 100 includes three principal sections that are
described in turn, a location-distributed transmitter
stage 105, a passive switching stage 110, and a locationdistributed
receiver stage 115. The system 100 is
configurable to support different values o f M and N .
Accordingly a generalized architecture is used to
describe the system 100, with more specific examples
being used to describe some detailed aspects o f the
system 100.
The transmit stage 105 includes N optical power
waveguides 120-1, 120-2... 120-N, collectively referred to
as waveguides 120. The transmit stage 105 further
includes input microcavity resonator sets 125-1, 125-2...
125-N, wherein each set is optically coupled to a
corresponding one o f the optical power waveguides 120-1,
120-2 to 120-N. Each of the microcavity resonator sets
125-1 to 125-N includes M avitv resonators 130, as
further described below. Each microcavity resonator set
125 may include, e.g. an optical ring resonator
(microring) or an optical disk resonator (microdisk)
reconf igurably configured to resonate at an optical
wavelength, e.g. in the S band {1460 n - 1530 n ), the C
band (1530 n - 1565 nm) or the L band (1565 n - 1625
n ) . The remaining discussion refers to the microcavity
resonators as ring resonators without limitation thereto.
The microcavity resonator sets 125 may therefore also be
referred to as ring resonators sets 125.
Each of the N waveguides 120-1 to 120-N receives an
unmodulated, multi-channel, optical signal 200 (see FIG.
2 ) that is a superposition of unmodulated wavelength
components. FIG. 2 schematically illustrates the spectrum
of a representative unmodulated, multi-channel, optical
signal 200 that includes six equally spaced, wavelength
components , ... l . The individual wavelengths may be
spaced by a WDM grid, frequency spacing Af (or equivalent
wavelength spacing Dl ), e.g. a regular, about even spacing
of the wavelength components by a same frequency
difference, e.g. about 100 GHz. Six wavelength components
are shown, but embodiments are not limited to any
particular number of wavelength components .
Returning to FIG. 1 , and considering the ring
resonator set 125-1 as an example, this set includes M
ring resonators 130-11, 130-21... 130-M1 . Each of the ring
resonators 130-11, 130-21... 130-M1 may be controlled to
operate with a resonant wavelength approximately equal to
one of the center wavelengths, i.e., l , l2 / — , of the M
wavelength components of the unmodulated, multi-channel,
optical signal 200.
In the transmitter stage 105, each of the ring
resonators 130-11, 130-21... 130-M1 is optically coupled to
the optical power waveguide 120-1 such that a wavelength
component of an optical signal having a wavelength near
the resonant wavelength of a particular k-th ring
resonator 130-lk couples to that ring resonator. A
controller 135 may provide a quasi-static control signal
that sets a nominal resonant frequency of a unique one of
the ring resonators 130-11, 130-21... 130-M1 to one of the
wavelength components . The nominal resonant frequency may
be changed by electro-optic, thermal or free-carrier
modulation of the optical path lengths of the resonators
130. A data modulator (not shown) may modulate the
resonant frequency of the ring resonators 130 to impart
data on the coupled signal, e.g. by binary phase shift
keying or on-off keying. For example, the resonant
frequency of each resonator 130 may be rapidly switched
between two resonant frequencies offset by a small amount
from the nominal resonant frequency. Additional suitable
examples of such modulation may be described in the 525
Application. Thus the controller 135 may operate to map
the data stream delivered to each ring resonator 130 to a
particular wavelength channel.
The wavelength components l ...l propagating within
each waveguide 120 may b e modulated independently. Thus,
the transmitter stage can produce MxN independently datamodulated
optical carriers . A t outputs o f the waveguides
120-1...12 0- each optical signal may have any one of the
wavelengths l ...l .
In the switching stage 110, a wavelength
demultiplexer 145 includes input ports 150-1...150-N and
output ports 155-1...155-M. A t the input ports 150, the
wavelength demultiplexer 145 receives the modulated
optical signals from the waveguides 120 via corresponding
optical paths 140-1... 140- . While in the illustrated
embodiments the optical paths 140 are shown as being
physically located between the transmit stage 105 and the
switching stage 110, in other embodiments segments of the
optical paths 140 may be physically located between the
switching stage 110 and the receiver stage 115. The
optical paths 140 may include, e.g., segments o f single
mode optical fibers of various lengths . Short path
lengths may be used in embodiments for which the system
100 is implemented as, e.g., an integrated photonic
optical processor. Long path lengths may be used in
embodiments for which the system 100 is implemented as,
e.g., in a long-haul communication system. A medium path
length may be used in embodiments for which the system
100 is implemented as, e.g., a communication network
inside of a data processing center.
In various embodiments, the wavelength demultiplexer
145 demultiplexes the wavelength components of the
optical carrier signals received at each input port 150
and routes these components to the output ports 155 in a
wavelength-selective manner. For example, the wavelength
demultiplexer 145 may route each one of the M wavelength
components received from the waveguide 120-1 to a
corresponding one of the M output ports 155.
In various embodiments, the wavelength demultiplexer
145 typically routes the individual wavelength components
of a WDM optical signal in a sequential and cyclic
fashion to the output ports 155. For example, if the
input 150-1 receives a WDM optical signal with M
wavelength components in a wavelength-sequential sequence
, l2, l3... l , these components may be routed to the
output ports 155 such that a k-th wavelength is output
at the first output 155-1, a next cyclically sequential
wavelength is output at the second output 155-2, and
so on such that the wavelength + - is output at the M -
th output 155-M. Here, {k+M-1} designates the integer
equal to k+M-1 modulo M and located in the interval [1,
M ] .
Thus, the demultiplexer 145 may be any conventional
wavelength-cyclic optical demultiplexer, e.g., an A Gbased
optical demultiplexer. Herein, such a demultiplexer
may be referred to as a cyclic optical demultiplexer.
F Gs . 4A-4D illustrate without limitation the
ordering of channel frequencies at the outputs of the
wavelength demultiplexer 145 in a more specific
embodiment. In the following discussion, for example and
without limitation, N and M are each taken to be 4 , and
the wavelength demultiplexer 145 implements cyclic
permutations of wavelength components . The center
wavelength of each wavelength channel is described as lM.
In FIG. 4A, wavelength components l , l2, l and l
received at the input port 150-1 are wavelengthselectively
routed by the wavelength demultiplexer 145 to
the output ports 155-1, 155-2, 155-3, and 155-4,
respectively. In FIG. 4B, wavelength components , l2, l3,
and received at the input port 150-2 are wavelengthselectively
routed by the wavelength demultiplexer 145 to
output ports 155-4, 155-1, 155-2 and 155-3, respectively.
In FIG. 4C, wavelength components l , l2, l , and 4
received at the input port 150-3 are wavelengthselectively
routed by the wavelength demultiplexer 145 to
output ports 155-3, 155-4, 155-1, and 155-2,
respectively. In FIG. 4D, wavelength components l , l , 3 ,
and l received at the input port 150-4 are wavelengthselectively
routed by the wavelength demultiplexer 145 to
output ports 155-2, 155-3, 155-4 and 155-1, respectively.
The wavelength demultiplexer 145 is not limited to
any particular implementation. Some convenient
implementations include an arrayed waveguide grating
(A G ) based optical cross-connect. As known to those
skilled in the optical arts, an AWG based optical crossconnect
may be used to route a sequence of wavelength
components of a WDM optical signal to a parallel, spatial
sequence of optical outputs in a wavelength-selective
manner. A s already mentioned, an AWG based wavelength
selective cross-connect may also route wavelength
channels in a manner that is cyclic in the sequence of
components to the outputs. Moreover, an AWG-based device
may be implemented in a planar waveguide process, e.g.
silica on an SOI substrate, thereby being well suited to
integration in a photonic integrated circuit (PIC) .
Embodiments of the wavelength demultiplexer 145 are
not limited to implementation with an AWG. For example, a
cyclic wavelength demultiplexer may be also based on an
Echelle grating. Such a grating directs substantial
amounts of received light into multiple diffraction
orders so that each of the M optical outputs of device
145 may be connected to receive light from multiple
orders. In some alternate embodiments, the switching
stage 110 may b e implemented using an electronicallycontrolled
switching matrix. For example, 2X2 electrooptic
switches may be configured to implement an MxN
matrix, with the switches being electronically
controlled. Skilled practitioners o f the optical arts are
familiar with such switching matrixes. However, the size
of such matrixes may grow rapidly with N making such
embodiments cumbersome and expensive as N becomes large.
Returning to FIG. 1 , the receiver stage 115 includes
a plurality o f waveguides 160, e.g. one waveguide 160-1,
160-2... 160— M optically connected to a corresponding one
of the output ports 15 5 of the wavelength demultiplexer
145. Each waveguide 160 is associated with an output ring
resonator set 165. Thus, for example, the waveguide 160-1
is associated with an output ring resonator set 165-1,
the waveguide 160-2 is associated with an output ring
resonator set 165-2, and so on. The ring resonator set
165-1 includes N ring resonators 170-11...170-N1, e.g. one
ring resonator corresponding to each o f the ring
resonator sets 125.
Each ring resonator 170-11...170-N1 may be configured
to selectively couple to light propagating within the
waveguide 160-1 at one of the channel wavelengths li -l .
Thus, e.g. the ring resonator 170-11 may be coupled to
light propagating at , the ring resonator 170-21 may be
coupled to light propagating at l , and so on. Similarly,
a ring resonator 170-12 may be coupled to light
propagating at i within the waveguide 160-2, a ring
resonator 170-22 may be coupled to light propagating at l2
within the waveguide 160-2, and so on.
A receiver controller 175 controls the resonant
frequency of each of the ring resonators 170. The
controller 175 may configure each of the ring resonators
170 to have a nominal resonant frequency corresponding to
any one of the channel wavelengths l , l2, l3, and l . That
is, the resonant frequency of each of the ring
resonators 170-1Q, 170-NQ of ring resonator set 65-
may be set to couple to a selected one of the channel
wavelengths, thereby selectively coupling one of N
wavelength components in the optical waveguide 160 to
that ring resonator 170. Typically, within a wavelength
set 165, each of the channel wavelengths , l2, l3, and l
is assigned to only one ring resonator of a ring
resonator set 165-Q.
Each of the ring resonators 170 is paired with an
optical-to-electrical transducer 300, referred to herein
as a domain converter 300. FIG. 3 illustrates a detail
view of a representative domain converter 300. Each
domain converter 300 includes a waveguide section 310 and
a photodiode 320. The waveguide section 310 is located
proximate the associated ring resonator 170 such that
light is coupled from the ring resonator 170 to the
waveguide section 310. The photodiode 320 converts the
coupled optical signal to a corresponding electrical
signal for further processing, e.g. demodulation of the
received data stream. Each of the domain converters 300
may be identified by the same suffix as its associated
ring resonator 170. Thus, e.g. a domain converter 300-11
is associated with the ring resonator 170-11, a domain
converter 300-21 is associated with the ring resonator
170-21, etc.
Returning to FIG. 1 , the controllers 135 and 175 act
in a coordinated manner to transmit data from a selected
one of the NM ring resonators 130 to a selected one of
the MN ring resonators 170. For example, if it is desired
to transmit the data stream received by the ring
resonator 130-21 to the ring resonator 170-22, the
controller 135 may configure the ring resonator 130-21 to
couple to the channel wavelength l2, thereby modulating
the 2 carrier with a data stream. The wavelength
demultiplexer 145 routes the l2 carrier to the output 155-
2 (see FIG. 4A) . The receiver controller 175 configures
the ring resonator 170-22 to also couple to the channel
wavelength l2 . Then, the transducer 300-22 converts the
optical signal to the electrical domain for processing.
It will be apparent to those skilled in the art that the
described principle may be used to transmit data received
by any of the ring resonators 130 to any desired instance
of the transducer 300 thereby implementing a general MxN
opto-electrical switching network.
Figure 1A schematically illustrates how the optical
network 100 may optically provide data connections
between electrical devices 800-1, 800-N and M
electrical devices 900-1, 900-M. Each electrical
device 800-R is connected to electrically transmit M data
streams to a corresponding M ring resonator set 125-R.
Each electrical device 900-S is connected to electrically
monitor N data streams from a corresponding N ring
resonator set 165-S. For that reason, any individual
electrical device 800-R is able to communicate a digital
data stream to any individual electrical device 900-S via
the optical network 100. That is, the N electrical
devices 800-1 to 800-N may independently communicate, in
parallel, with the M electrical devices 900-1 to S00-M
via the optical network 100. A s an example, the
electrical devices 800-1 to 800-N may be N digital data
processors of a data center, and the electrical devices
900-1 to 900-M may be M digital data storage devices of
the data center. Then, the optical network 100 enables
each of the digital data processors to selectively
route a separate digital data stream to each of the M
digital data storage devices.
In other embodiments, the optical network 100 may
provide such parallel digital data connections between a
first set of N data devices and a second set of M data
devices. In the first set, the N individual devices may
include various types of conventional devices that output
digital data streams. In the second set, the M individual
devices may include various types of conventional devices
that input digital data streams.
The above embodiments have been described with each
of the ring resonators 130 being configured to couple to
one of the same set of channel wavelengths, e.g. l , l2,
l and l . In such embodiments it may be preferable that
the wavelength demultiplexer 145 provide cyclic
permutations of the input channel wavelengths to the
outputs, as previously described in various embodiments.
In some other embodiments, the set of wavelengths at
which each ring resonator set 125 couples to optical
carriers is not constrained to be the same as the set of
wavelengths at which the others of the ring resonator
sets 125. In such cases, the wavelength demultiplexer 145
need not provide cyclic permutations of the input
wavelength channels at its outputs. In particular, some
such embodiments may select the wavelengths such that no
two channels with a same wavelength ever simultaneously
propagate on a same waveguide.
In embodiments in which the controllers 135 and 175
are collocated, coordination of the operation of the
controllers may be easily accomplished using a data path
180 to communicate, e.g. timing information and/or data
conveying the data channels selected for communications.
In embodiments in which the controllers 135 and 175 are
physically remote, such as for long-haul communications,
the data path 180 may communicate a selected data channel
and/or channel scheduling data to coordinate operation of
the controllers 135 and 175.
The optical components of the system 100 may be
formed conventionally, e.g. as planar structures formed
over a silicon substrate, e.g. a silicon wafer. A
convenient platform on which to form the system 100 is a
silicon-on— insulator (SOI) wafer, but embodiments of the
invention are not limited thereto. For example, a
dielectric layer, e.g. plasma oxide, could be formed on
any suitable substrate, and a silicon layer could be
formed thereover by any suitable method. Other
embodiments may use a substrate formed from, e.g. glass,
sapphire or a compound semiconductor. Those skilled in
the pertinent art are familiar with such fabrication
techniques .
In some embodiments optical and electrical
components of the system 100 are formed on a same
substrate. In such a system, e.g. silicon-based
electronic components may be formed on one region of a
photonic integrated circuit (PIC) , and optical components
may be formed on another region of the PIC. Interconnects
may provide conductive paths from the domain converters
300 to the control stage 110.
In other embodiments, such as represented by FIGs .
5A-5C, portions of an opto-electronic system may be
formed on separate substrates. FIG. 5A illustrates one
such system 500, formed according to one embodiment.
Electrical components are formed on an electrically
active substrate 510, optical components are formed on an
optical substrate 520, and interconnects are formed on an
interconnect substrate 530. The substrates 510, 520 and
530 are then face-joined to form the operable system 500.
The electronic substrate 510 may include electronic
components such as transistors, diodes, resistors and
capacitors to implement electrical functions of the
system 100. Such functions may include, but are not
limited to, the functions of the controllers 135 and 175,
including switching, signal conditioning and
amplification. The electronic substrate 510 may include a
base layer 540, e.g. a silicon wafer, and active layers
550 that include electronic devices and interconnects.
The substrate 510 may be formed from any conventional
and/or future-discovered processes, and is not limited to
any particular material types . By way of example, without
limitation, such materials may include silicon, silica,
SiN, InP, GaAs, copper interconnects, aluminum
interconnects, and/or various barrier materials.
The optical substrate 520 may include optical
components of the transmit stage 105, the switching stage
110, and the receiver stage 115. Such components include,
e.g. grating couplers, A Gs, optical waveguides,
microcavity resonators, optical power splitters, optical
power combiners, and photodiodes . The optical waveguides
may be formed from planar or ridge structures by
conventional and/or novel processes. Such components
typically include an optical core region and an optical
cladding region. The core regions may be formed from any
conventional or nonconventional optical material system,
e.g. silica, silicon, LiNb0 3, a compound semiconductor
alloys such as GaAlAs, GaAIN or InP, or an electro-optic
polymer . Some embodiments described herein are
5 implemented in Si as a nonlimiting example. While
embodiments within the scope of the invention are not
limited to Si, this material provides some benefits
relative to other material systems, e.g. relatively low
cost and well-developed manufacturing infrastructure . The
.0 cladding region may include homogenous or heterogeneous
dielectric materials, e.g. silica or benzocyclobutene
(BCB) . Some portions of the cladding region may include
air, which for the purposes of this discussion includes
vacuum.
.5 The interconnect substrate 530 includes additional
interconnect structures that may configure operation of
the system 500. The interconnect substrate 530 may
include any dielectric and conductive {e.g. metallic)
materials needed to implement the desired connectivity.
0 In some cases, formation of the substrate 530 may include
the use of a handle wafer to provide mechanical support,
after which the substrate 530 is removed from the handle.
The electronic substrate 510 may be joined to the
interconnect substrate 530 by, e.g. a bump process or, as
5 illustrated, a wafer bonding process. Such processes are
well known to those skilled in semiconductor
manufacturing, and may include, e.g. chemical mechanical
polishing (CMP) to prepare the substrate surfaces for
bonding. The interconnect substrate 530 may be joined to
the optical substrate 520 by, e.g. a bump process as
illustrated in FIG. 5A, or a wafer bonding process as
illustrated in FIG. 5B. In the bump process, solder balls
560 join interconnect structures in the substrate 530 to
metalized via structures 570 in the optical substrate
520. The via structures 57 0 may provide electrical and/or
mechanical connectivity between substrates 520 and 530.
FIG. 5C illustrates another embodiment of the system
100 in which the interconnections and optical functions
are combined into an integrated substrate 580. In the
illustrated embodiment the substrate 580 includes the
optical substrate 520 and interconnect layers 530a and
530b formed on either side of the optical substrate 520.
The integrated substrate 580 may then be joined to the
substrate 510 by, e.g. wafer bonding.
The separate formation of the electronic substrate
510, the interconnect substrate 530 and the optical
substrate 520 may serve at least one of several purposes.
First, the thermal budget required to form some features,
e.g. high quality waveguides in the optical substrate
520, may be incompatible with other features, such as
doping profiles of transistors in the electrically active
substrate 510. Second, the substrates 510, 520 and 530
ay be formed separately by entities with specialized
skills and/or fabrication facilities and joined by
another entity. Third, where security is desired
regarding the function of the assembled system 500, the
fabrication operations may be assigned to the various
entities such that no one entity acquires sufficient
knowledge to determine the specific functionality of the
device. The final assembly may then be completed under
secure conditions to ensure confidentiality of the
operation of the assembled system 500.
Turning to FIG. 6 , a method 600 is provided for,
e.g. forming the system 100 according to various
embodiments. The steps of the method 600 are described
without limitation by reference to elements previously
described herein, e.g. in FIGs . 1-5. The steps of the
method 600 may be performed in another order than the
illustrated order, and in some embodiments may be omitted
altogether and/or performed concurrently or in parallel
groups. This method 600 is illustrated without limitation
with the steps thereof being performed in serial fashion,
such as by separate processing on different substrates.
Other embodiments, e.g. those utilizing a common multiple
substrate, may perform the steps partially or completely
in parallel, and in any order.
In a step 610, an input waveguide, e.g. the
waveguide 120-1, is formed and optically connected to a
wavelength demultiplexer, e.g. the wavelength
demultiplexer 145. In a step 620 microcavity resonators
of a first input set of microcavity resonators are
formed. These resonators are located adjacent the input
waveguide such that each microcavity resonator is
configured to controllably couple to a corresponding one
of a plurality of frequency channels propagating within
the input waveguide.
Some embodiments of the method 600 include a step
630, in which a plurality of output waveguides is formed.
Each waveguide is optically connected to the wavelength
demultiplexer. The wavelength demultiplexer is configured
to route each carrier signal to a corresponding one of
the output waveguides.
Some such embodiments include a step 640, in which a
plurality of output microcavity resonator sets is formed.
Each resonator set includes a corresponding plurality of
microcavity resonators. Each microcavity resonator of
each output set is located adjacent a same corresponding
one of the output waveguides such that the microcavity
resonators of each set may controllably couple to a
corresponding different wavelength channel propagating
within the corresponding output waveguide.
FIG. 7 presents a method 700, e.g. of forming the
system 100. The steps of the method 700 are described
without limitation by reference to elements previously
described herein, e.g. in FIGs . 1-5. The steps of the
method 700 may be performed in another order than the
illustrated order, and in some embodiments may be omitted
altogether and/ or performed in parallel or in parallel
groups. Herein and in the claims, "provided" or
"providing" means that a device, substrate, structural
element, etc., may be manufactured by the individual or
business entity performing the disclosed method, or
obtained thereby from a source other than the individual
or entity, including another individual or business
entity ·
The method includes a step 710, in which a first
substrate is provided. The substrate has an input
waveguide optically connected to a wavelength
demultiplexer. A first input microcavity resonator set
including a plurality of microcavity resonators is
located adjacent the input waveguide.
In a step 720 a second substrate is provided. The
second substrate has an electronic controller formed
thereover. The controller is configured to control the
microcavity resonators to controllably couple each to a
corresponding one of a plurality of frequency channels of
an optical signal propagating within the input waveguide.
In a step 730 the first and second substrates are
joined, thereby connecting the controller to the
microcavity resonators .
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 .

WE CLAIMS:-
1 . A system comprising:
a first plurality of separate sets of optical ring
resonators ;
a second plurality of separate sets of optical ring
resonators; and
an optical multiplexer/demultiplexer having a set of
optical inputs and a set of optical outputs; and wherein:
each set of the first plurality of separate sets is
optically connected to a corresponding one of the optical
inputs of the optical multiplexer/demultiplexer; and
each set of the second plurality of separate sets is
optically connected to a corresponding one of the optical
outputs of the optical multiplexer/demultiplexer.
2 . The system of claim 1 , further comprising a
plurality of first devices, each first device being
connected to modulate digital data streams onto optical
carriers via the ring resonators of a corresponding one
of the sets of the first plurality.
3 . The system of claim 2 , further comprising a
plurality of first apparatuses, each first apparatus
being connected to demodulate digital data streams from
optical carriers via the ring resonators of a
corresponding one of the sets of the second plurality.
4 . A system, comprising:
an input waveguide optically connected to an input
of an optical demultiplexer; and
a first microcavity resonator set including a
plurality of microcavity resonators located adjacent said
input waveguide such that each microcavity resonator is
able to couple to a corresponding one of a plurality of
wavelength channels of an optical signal propagating
within said input waveguide.
5 . The system of Claim 4 , further comprising a
plurality of output waveguides, each output waveguide
being optically connected to a corresponding optical
output of said wavelength demultiplexer.
6 . The system of Claim 5 , further comprising a
plurality of output microcavity resonator sets each
including a corresponding plurality of microcavity
resonators, each microcavity resonator set being
optically coupled to a corresponding one of said output
waveguides, the microcavity resonators of each output set
being able to separately couple to wavelength channels of
an optical signal propagating within said corresponding
one of the output waveguides.
7 . A method comprising:
providing an input waveguide optically connected to
a wavelength demultiplexer; and
providing a first input microcavity resonator set
including a plurality of microcavity resonators located
adjacent said input waveguide such that each microcavity
resonator is able to couple to a corresponding one of a
plurality of wavelength channels propagating within said
input waveguide .
8 . The method of Claim 7 , further comprising
providing a plurality of output waveguides optically
connected to said wavelength demultiplexer.
9 . The method of Claim 8 , further comprising
providing a plurality of output microcavity resonator
sets each including a corresponding plurality of
microcavity resonators, each microcavity resonator set
being optically coupled to a corresponding one of said
output waveguides .
10. A method, comprising:
providing a first substrate having an input
waveguide optically connected to a wavelength
demultiplexer, and a first input microcavity resonator
set including a plurality of microcavity resonators
located adjacent said input waveguide, each of said
microcavity resonators being configured to couple to a
different frequency of an optical signal propagating
within the input waveguide;
providing a second substrate having an electronic
controller formed thereover, said controller configured
to control said microcavity resonators to controllably
couple to a corresponding one of the frequency channels;
and
joining said first and second substrates thereby
connecting said controller to said microcavity
resonators .