# US 12,181,737 B2 · Optical switching apparatus

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- Number: US 12,181,737 B2
- Document ID: US12181737B2
- Status: Granted
- Kind: B2
- Application number: 17/766,454
- Filed: 2019-10-11
- Published: 2023-03-30
- Granted: 2024-12-31
- Earliest claimed: 2019-10-11
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Yusuke Muranaka; Yohei Sakamaki; Toshikazu Hashimoto
- Web page: https://patentgrep.com/patent/US12181737B2

## CPC

- G02F 1/035: in an optical waveguide structure
- 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 6/354: {Switching arrangements, i.e. number of input/output ports and interconnection types}
- G02B 6/3546: {NxM switch, i.e. a regular array of switches elements of matrix type constellation}
- G02B 6/3556: {NxM switch, i.e. regular arrays of switches elements of matrix type constellation}
- G02F: OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS

## Abstract

A low-loss optical switch device with a smaller number of ports for an optical switch in a network and node device capable of transmitting OCS-type and OPS-type optical signals is provided. The optical switch device includes: a high-speed add/drop optical switch composed of a plurality of optical switches, the optical switch having an optical waveguide structure made of a material whose refractive index or absorption coefficient changes on the order of nanoseconds, and the optical switch changing the refractive index or the absorption coefficient to perform switching of both OCS optical signals, which are optical-circuit-switching-type optical signals, and OPS optical signals, which are optical-packet-switching-type optical signals; and a plurality of circulators connected to an input port and an output port of the high-speed add/drop optical switch.

## Claims

### Claim 1

An optical switch device provided in a node device constituting a network and having a plurality of optical input ports and a plurality of optical output ports, comprising:
a high-speed add/drop optical switch composed of a plurality of optical switches, the optical switch having an optical waveguide structure made of a material whose refractive index or absorption coefficient changes on the order of nanoseconds, and the optical switch changing the refractive index or the absorption coefficient to perform switching of both Optical-Circuit-Switching (OCS) optical signals and Optical-Packet-Switching (OPS) optical signals and
a plurality of circulators connected to an input port and an output port of the high-speed add/drop optical switch, wherein
the node device is a Reconfigurable Optical Add Drop Multiplexer (ROADM) node device having a wavelength selective switch,
the high-speed add/drop optical switch is arranged after the wavelength selective switch and includes:
a first optical switch unit composed of a plurality of optical switches that switches the OCS optical signals and the OPS optical signals to a first preset optical output port and perform an add/drop process between the OCS optical signals and the OPS optical signals; and
a second optical switch unit composed of a plurality of optical switches that switches the OPS optical signals to the first preset optical output port of the first optical switch unit and performs an add/drop process on the OPS optical signals,
wherein the first optical switch unit switches the OPS optical signals to a second preset optical port of the second optical switch unit.

### Claim 2 (depends on 1)

The optical switch device according to claim 1, further comprising:
a network controller that controls switching in the first optical switch unit; and
a label table that controls switching in the second optical switch unit on the basis of labels of the OPS optical signals.

### Claim 3 (depends on 2)

The optical switch device according to claim 2, wherein
if K, L, M, and N are integers of 1 or more,
the first optical switch unit includes an N×(K+L) optical switch having an N×(K+L) port configuration and a (K+L)×N optical switch having a (K+L)×N port configuration,
the second optical switch unit includes an M×K optical switch having an M×K port configuration and a K×M optical switch having a K×M port configuration,
L ports on an output side of the N×(K+L) optical switch are connected to L ports on an input side of the (K+L)×N optical switch, and K ports on the output side of the N×(K+L) optical switch are connected K ports on the input side of the K×M optical switch, and
K ports on the output side of the M×K optical switch are connected to K ports on the input side of the (K+L)×N optical switch.

### Claim 4 (depends on 1)

The optical switch device according to claim 1, wherein
if K, L, M, and N are integers of 1 or more,
the first optical switch unit includes an N×(K+L) optical switch having an N×(K+L) port configuration and a (K+L)×N optical switch having a (K+L)×N port configuration,
the second optical switch unit includes an M×K optical switch having an M×K port configuration and a K×M optical switch having a K×M port configuration,
L ports on an output side of the N×(K+L) optical switch are connected to L ports on an input side of the (K+L)×N optical switch, and K ports on the output side of the N×(K+L) optical switch are connected K ports on the input side of the K×M optical switch, and
K ports on the output side of the M×K optical switch are connected to K ports on the input side of the (K+L)×N optical switch.

### Claim 5 (depends on 4)

The optical switch device according to claim 4, wherein
if J is an integer of 2 or more,
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, and the K×M optical switch are respectively 1×J optical switches having a 1×J port configuration, and at least one of the 1×J optical switches is composed of an 1×J optical coupler and J light absorption gates.

### Claim 6 (depends on 5)

The optical switch device according to claim 5, wherein a light absorption gate is provided after the N×(K+L) optical switch.

### Claim 7 (depends on 5)

The optical switch device according to claim 5, wherein
the N×(K+L) optical switch and the (K+L)×N optical switch, the N×(K+L) optical switch and the K×M optical switch, and the M×K optical switch and the (K+L)×N optical switch are connected by an optical waveguide, and
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, the K×M optical switch, and the optical waveguide are monolithically integrated on the same chip.

### Claim 8 (depends on 4)

The optical switch device according to claim 4, wherein
if J is an integer of 2 or more,
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, and the K×M optical switch are respectively 1×J optical switches having a 1×J port configuration, and at least one of the 1×J optical switches has a configuration in which a plurality of 1×2 Mach-Zehnder interferometers or a plurality of 2×2 Mach-Zehnder interferometers are connected in multiple stages.

### Claim 9 (depends on 8)

The optical switch device according to claim 8, wherein a light absorption gate is provided after the N×(K+L) optical switch.

### Claim 10 (depends on 8)

The optical switch device according to claim 8, wherein
the N×(K+L) optical switch and the (K+L)×N optical switch, the N×(K+L) optical switch and the K×M optical switch, and the M×K optical switch and the (K+L)×N optical switch are connected by an optical waveguide, and
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, the K×M optical switch, and the optical waveguide are monolithically integrated on the same chip.

### Claim 11 (depends on 4)

The optical switch device according to claim 4, wherein a light absorption gate is provided after the N×(K+L) optical switch.

### Claim 12 (depends on 4)

The optical switch device according to claim 4, wherein
the N×(K+L) optical switch and the (K+L)×N optical switch, the N×(K+L) optical switch and the K×M optical switch, and the M×K optical switch and the (K+L)×N optical switch are connected by an optical waveguide, and
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, the K×M optical switch, and the optical waveguide are monolithically integrated on the same chip.

### Claim 13 (depends on 11)

The optical switch device according to claim 11, wherein
the N×(K+L) optical switch and the (K+L)×N optical switch, the N×(K+L) optical switch and the K×M optical switch, and the M×K optical switch and the (K+L)×N optical switch are connected by an optical waveguide, and
the N×(K+L) optical switch, the (K+L)×N optical switch, the M×K optical switch, the K×M optical switch, and the optical waveguide are monolithically integrated on the same chip.