# US 11,112,564 B2 · Apparatus, systems, and methods for nonblocking optical switching

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- Number: US 11,112,564 B2
- Document ID: US11112564B2
- Status: Granted
- Kind: B2
- Application number: 16/827,795
- Filed: 2020-03-24
- Published: 2020-09-10
- Granted: 2021-09-07
- Earliest claimed: 2017-05-17
- Assignees: Massachusetts Institute of Technology
- Applicants: Massachusetts Institute of Technology
- Inventors: Gregory R. Steinbrecher; Dirk Robert Englund
- Web page: https://patentgrep.com/patent/US11112564B2

## CPC

- G02B 6/356: {in an optical cross-connect device, e.g. routing and switching aspects of interconnecting different paths propagating different wavelengths to (re)configure the various input and output links (switching polarized beams G02B6/3594; power equalizers G02B6/356 and G02B6/3594; path selecting means H04Q11/0001)}
- G02B 6/29355: {Cascade arrangement of interferometers}
- G02B 6/3542: {Non-blocking switch, e.g. with multiple potential paths between multiple inputs and outputs, the establishment of one switching path not preventing the establishment of further switching paths}
- G02B 6/3546: {NxM switch, i.e. a regular array of switches elements of matrix type constellation}
- H04Q 11/0005: {Switch and router aspects}
- G02B 6/29395: {configurable, e.g. tunable or reconfigurable (switching G02B6/35)}
- H04Q 2011/0015: {using splitting combining}
- H04Q 2011/0035: {using miscellaneous components, e.g. circulator, polarisation, acousto/thermo optical}
- H04Q 2011/0047: {Broadcast; Multicast}
- H04Q 2011/0052: {Interconnection of switches}
- H04Q 2011/0058: {Crossbar; Matrix}
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- H04Q: SELECTING (switches, relays, selectors H01H; wireless communication networks H04W)

## Abstract

A method of nonblocking optical switching includes guiding a first optical beam from a first input to a first output via a first path through an optical switching fabric. The first path traverses a phase shifter disposed between a pair of cascaded Mach-Zehnder interferometers. The method also includes receiving a second optical beam for a second path intersecting with the first path through the optical switching fabric. The method also includes moving the first optical beam from the first path to a third path connecting the first input to the first output without intersecting the second path. The method also includes shifting a phase of the first optical beam, with the phase shifter, while moving the first optical beam from the first path to the third path to prevent the first optical beam from interfering with the second optical beam.

## Claims

### Claim 1

An optical network, comprising:
a nonblocking optical switch comprising:
a substrate;
a plurality of input ports fabricated in the substrate to receive a plurality of input optical beams;
a plurality of interconnected Mach-Zehnder interferometers (MZIs), in optical communication with the plurality of input ports, to perform an arbitrary uniform transformation of the plurality of input optical beams so as to generate a plurality of output optical beams; and
a plurality of output ports, in optical communication with the plurality of interconnected MZIs, to output the plurality of output optical beams;
a plurality of computer servers, each computer server in the plurality of computer servers comprising:
an input interface optically coupled to a corresponding output port in the plurality of output ports; and
an output interface optically coupled to a corresponding input port in the plurality of input ports; and
a controller, operably coupled to the plurality of computers and the nonblocking optical switch, to control communication between a first computer server in the plurality of computer servers and a second computer server in the plurality of computer servers via the nonblocking optical switch, further comprising:
a first phase shifter disposed in an arm of a first MZI of the plurality of MZIs; and
a second phase shifter in optical communication with an output of the first MZI,
wherein the controller is configured to control a setting of the first phase shifter and a setting of the second phase shifter so as to cause the nonblocking optical switch to direct data from the first computer server in the plurality of computer servers to the second computer server in the plurality of computer servers.

### Claim 2 (depends on 1)

The optical network of claim 1, wherein the controller is further configured to control the setting of the first phase shifter and the setting of the second phase shifter so as to cause the nonblocking optical switch to multicast the data from the first computer server to at least two other computer servers in the plurality of computer servers.

### Claim 3 (depends on 1)

The optical network of claim 1, wherein the controller is configured to cause the nonblocking optical switch to direct the data from the first computer server in the plurality of computer servers to a third computer server in the plurality of computer servers via a second path.

### Claim 4 (depends on 1)

The optical network of claim 1, further comprising:
a plurality of field-programmable gate arrays (FPGA), each FPGA in the plurality of FPGAs connecting a corresponding computer server in the plurality of computer servers with the nonblocking optical switch.