# US 10,374,388 B2 · Optical semiconductor device

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- Number: US 10,374,388 B2
- Document ID: US10374388B2
- Status: Granted
- Kind: B2
- Application number: 15/454,202
- Filed: 2017-03-09
- Published: 2018-02-01
- Granted: 2019-08-06
- Earliest claimed: 2016-07-28
- Assignees: Mitsubishi Electric Corporation
- Applicants: Mitsubishi Electric Corporation
- Inventors: Naoki Nakamura; Eiji Nakai
- Web page: https://patentgrep.com/patent/US10374388B2

## CPC

- H01S 5/0421: {characterised by the semiconducting contacting layers (electrodes H01S5/0425)}
- H01S 5/026: Monolithically integrated components, e.g. waveguides, monitoring photo-detectors, drivers (stabilisation of output H01S5/06)
- H01S 5/2275: {mesa created by etching}
- H01S 5/34313: {with a well layer having only As as V-compound, e.g. AlGaAs, InGaAs}
- H01S 5/34326: {with a well layer based on InGa(Al)P, e.g. red laser}
- H01S 5/1003: {Waveguide having a modified shape along the axis, e.g. branched, curved, tapered, voids}
- H01S 5/1017: {Waveguide having a void for insertion of materials to change optical properties}
- H01S 5/2031: {characterized by special waveguide layers, e.g. asymmetric waveguide layers or defined bandgap discontinuities}
- H01S: DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL

## Abstract

An optical semiconductor device includes: an n-type semiconductor substrate; an n-type cladding layer provided on the n-type semiconductor substrate; an active layer of a semiconductor laser provided on the n-type cladding layer; a waveguide layer of a waveguide provided on the n-type cladding layer and having a side facing a side of the active layer; a p-type cladding layer provided on the active layer and the waveguide layer; and a middle layer provided between the side of the active layer and the side of the waveguide layer, provided between the n-type cladding layer and the waveguide layer, not provided on the active layer, and having a band gap greater than a band gap of the waveguide layer.

## Claims

### Claim 1

An optical semiconductor device comprising:
an n-type semiconductor substrate;
an n-type cladding layer provided on the n-type semiconductor substrate;
an active layer of a semiconductor laser provided on the n-type cladding layer, the active layer having an uppermost side;
a waveguide layer of a waveguide provided on the n-type cladding layer, the waveguide layer having a side facing a side of the active layer and having an uppermost side aligned with the uppermost side of the active layer;
a p-type cladding layer provided on the active layer and the waveguide layer; and
a middle layer provided between the side of the active layer and the side of the waveguide layer, provided between the n-type cladding layer and the waveguide layer, not provided on the active layer, and having a band gap greater than a band gap of the waveguide layer, the middle layer including a first side and a second side opposing the first side, the first and second sides facing the n-type cladding layer and the p-type cladding layer, respectively, and the second side aligned with the uppermost side of the active layer and aligned with the uppermost side of the waveguide layer.

### Claim 2 (depends on 1)

The optical semiconductor device according to claim 1, wherein the active layer has a multiquantum well structure and the waveguide layer has a bulk structure or a multiquantum well structure.

### Claim 3 (depends on 1)

The optical semiconductor device according to claim 1, wherein the middle layer is undoped or p-type.

### Claim 4 (depends on 1)

The optical semiconductor device according to claim 1, wherein the middle layer is InP, AlGaInAs or InGaAsP.

### Claim 5 (depends on 1)

The optical semiconductor device according to claim 1, wherein the active layer and the waveguide layer are InGaAsP or AlGaInAs.

### Claim 6 (depends on 1)

The optical semiconductor device according to claim 1, wherein the p-type cladding layer is provided on the active layer and the waveguide layer on an opposite side of the active layer and the waveguide layer from the n-type cladding layer.

### Claim 7 (depends on 1)

The optical semiconductor device according to claim 1, wherein the active layer and the waveguide layer extend along a same surface of the p-type cladding layer.

### Claim 8

An optical semiconductor device comprising:
a p-type semiconductor substrate;
a p-type cladding layer provided on the p-type semiconductor substrate;
an active layer of a semiconductor laser provided on the p-type cladding layer, the active layer having an uppermost side;
a waveguide layer of a waveguide provided on the p-type cladding layer, the waveguide layer having a side facing a side of the active layer and having an uppermost side aligned with the uppermost side of the active layer;
an n-type cladding layer provided on the active layer and the waveguide layer; and
a middle layer provided entirely between the side of the active layer and the side of the waveguide layer, provided entirely between the p-type cladding layer and the waveguide layer, provided entirely between the waveguide layer and the n-type cladding layer, not provided under the active layer, and having a band gap greater than a band gap of the waveguide layer, the middle layer including a first side and a second side opposing the first side, the first and second sides facing the n-type cladding layer and the p-type cladding layer, respectively.

### Claim 9 (depends on 8)

The optical semiconductor device according to claim 8, wherein the active layer has a multiquantum well structure and the waveguide layer has a bulk structure or a multiquantum well structure.

### Claim 10 (depends on 8)

The optical semiconductor device according to claim 8, wherein the middle layer is undoped or p-type.

### Claim 11 (depends on 8)

The optical semiconductor device according to claim 8, wherein the middle layer is InP, AlGaInAs or InGaAsP.

### Claim 12 (depends on 8)

The optical semiconductor device according to claim 8, wherein the active layer and the waveguide layer are InGaAsP or AlGaInAs.

### Claim 13 (depends on 8)

The optical semiconductor device according to claim 8, wherein the n-type cladding layer is provided on the active layer and the waveguide layer on an opposite side of the active layer and the waveguide layer from the p-type cladding layer.

### Claim 14 (depends on 8)

The optical semiconductor device according to claim 8, wherein the active layer and the waveguide layer extend along a same surface of the n-type cladding layer.