# US 12,111,559 B2 · Optical switch

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- Number: US 12,111,559 B2
- Document ID: US12111559B2
- Status: Granted
- Kind: B2
- Application number: 17/768,774
- Filed: 2019-10-16
- Published: 2023-03-30
- Granted: 2024-10-08
- Earliest claimed: 2019-10-16
- Assignees: Nippon Telegraph and Telephone Corporation
- Applicants: Nippon Telegraph and Telephone Corporation
- Inventors: Yusuke Muranaka; Tatsushi Nakahara; Toshikazu Hashimoto
- Web page: https://patentgrep.com/patent/US12111559B2

## CPC

- G02F 1/3136: {of interferometric switch type}
- G02B 6/12: of the integrated circuit kind (electric integrated circuits H10B, H10D84/00 - H10D89/00, H10F19/00, H10F39/00, H10H29/00, H10K19/00, H10K39/00, H10K59/00, H10N19/00, H10N39/00, H10N59/00, H10N69/00, H10N79/00, H10N89/00)
- G02F 1/015: based on semiconductor elements having potential barriers, e.g. having a PN or PIN junction (G02F1/03 takes precedence)
- G02F 1/313: in an optical waveguide structure
- 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

An optical switch includes 2-input 2-output optical switches connected in a multistage, an optical gate provided at each of N-th optical output ports, a driving circuit for operating the 2-input 2-output optical switch, and a driving circuit for operating the optical gate. The driving circuits for operating the 2-input 2-output optical switches are integrated in the vicinity of a control electrode on a waveguide of the 2-input 2-output optical switch. The driving circuits for operating the optical gates are integrated in the vicinity of a control electrode on a waveguide of the optical gates. The waveguide of the 2-input 2-output optical switch and the waveguide of the optical gate each has a p layer, an i layer, and an n layer sequentially formed on a semi-insulating substrate. The optical switch has a trench reaching the semi-insulating substrate between the 2-input 2-output optical switch and the optical gate.

## Claims

### Claim 1

An optical switch having one optical input port, and N-th optical output ports where N is an integer of 2 or more,
the optical switch, comprising:
2-input 2-output optical switches connected in a multistage for branching an optical signal inputted to the optical input port into N-th optical signals;
N-th optical gates respectively provided at the optical output ports;
driving circuits for operating the 2-input 2-output optical switches; and
driving circuits for operating the N-th optical gates independently of the 2-input 2-output optical switches;
wherein the driving circuits for operating the 2-input 2-output optical switches are integrated adjacent to a control electrode set on waveguides included in the 2-input 2-output optical switches,
the driving circuits for operating the N-th optical gates are integrated adjacent to a control electrode set on waveguides included in the N-th optical gates,
the waveguide included in the 2-input 2-output optical switch and the waveguide included in the N-th optical gates each have a p layer, an i layer, and an n layer sequentially formed on a semi-insulating substrate,
a trench reaching the semi-insulating substrate is included between the 2-input 2-output optical switches and the N-th optical gates, and the trench isolates the p layer in an area of the 2-input 2-output optical switches and a p layer in an area of the N-th optical gates.

### Claim 2 (depends on 1)

The optical switch according to claim 1, wherein the trench isolates a bias potential of the area of the 2-input 2-output optical switches and a bias potential of the area of the N-th optical gates.

### Claim 3 (depends on 2)

The optical switch according to claim 2,
wherein the 2-input 2-output optical switches are a 2-input 2-output MZI having two arm optical waveguides, and
two output ports of the 2-input 2-output MZI at a previous stage and one of two input ports of the 2-input 2-output MZI at a latter stage are connected in a tree shape by a connection optical waveguide.

### Claim 4 (depends on 2)

The optical switch according to claim 2, wherein the N-th optical gates are electro-absorption optical gates.

### Claim 5 (depends on 2)

The optical switch according to claim 2, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated on the same semi-insulating substrate.

### Claim 6 (depends on 2)

The optical switch according to claim 2, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches are integrated by flip chip mounting, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated by flip chip mounting.

### Claim 7 (depends on 1)

The optical switch according to claim 1,
wherein the 2-input 2-output optical switches are a 2-input 2-output MZI having two arm optical waveguides, and
two output ports of the 2-input 2-output MZI at a previous stage and one of two input ports of the 2-input 2-output MZI at a latter stage are connected in a tree shape by a connection optical waveguide.

### Claim 8 (depends on 7)

The optical switch according to claim 7,
wherein the connection optical waveguide has a p layer, an i layer, and an n layer sequentially formed on the semi-insulating substrate, and
the optical switch further has a trench formed in a cladding layer of the connection optical waveguide, and an electric cross talk of the n layer between the 2-input 2-output optical switches is isolated.

### Claim 9 (depends on 8)

The optical switch according to claim 8, wherein the N-th optical gates are electro-absorption optical gates.

### Claim 10 (depends on 8)

The optical switch according to claim 8, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated on the same semi-insulating substrate.

### Claim 11 (depends on 8)

The optical switch according to claim 8, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches are integrated by flip chip mounting, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated by flip chip mounting.

### Claim 12 (depends on 7)

The optical switch according to claim 7, wherein the N-th optical gates are electro-absorption optical gates.

### Claim 13 (depends on 7)

The optical switch according to claim 7, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated on the same semi-insulating substrate.

### Claim 14 (depends on 7)

The optical switch according to claim 7, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches are integrated by flip chip mounting, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated by flip chip mounting.

### Claim 15 (depends on 1)

The optical switch according to claim 1, wherein the N-th optical gates are electro-absorption optical gates.

### Claim 16 (depends on 15)

The optical switch according to claim 15, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated on the same semi-insulating substrate.

### Claim 17 (depends on 8)

The optical switch according to claim 8, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches are integrated by flip chip mounting, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated by flip chip mounting.

### Claim 18 (depends on 1)

The optical switch according to claim 1, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches, and the driving circuits for operating the N-th optical gates, and the N-th optical gates, are integrated on the same semi-insulating substrate.

### Claim 19 (depends on 1)

The optical switch according to claim 1, wherein the driving circuits for operating the 2-input 2-output optical switches, and the 2-input 2-output optical switches are integrated by flip chip mounting, and the driving circuits for operating the N-th optical gates, and the N-th optical gates are integrated by flip chip mounting.