# US 11,909,172 B2 · Method for manufacturing optical device and optical device

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- Number: US 11,909,172 B2
- Document ID: US11909172B2
- Status: Granted
- Kind: B2
- Application number: 17/141,223
- Filed: 2021-01-05
- Published: 2021-07-08
- Granted: 2024-02-20
- Earliest claimed: 2020-01-08
- Assignees: Asahi Kasei Kabushiki Kaisha; National University Corporation Tokai National Higher Education and Research System
- Applicants: Asahi Kasei Kabushiki Kaisha; National University Corporation Tokai National Higher Education and Research System
- Inventors: Ziyi Zhang; Maki Kushimoto; Hiroshi Amano
- Web page: https://patentgrep.com/patent/US11909172B2

## CPC

- H01S 5/0264: {for monitoring the laser-output}
- H01S 5/0201: {Separation of the wafer into individual elements, e.g. by dicing, cleaving, etching or directly during growth}
- H01S 5/0287: {Facet reflectivity}
- H01S 5/22: having a ridge or stripe structure
- H01S 5/4031: {Edge-emitting structures}
- H01S 5/0202: {Cleaving}
- H01S 5/02326: Arrangements for relative positioning of laser diodes and optical components, e.g. grooves in the mount to fix optical fibres or lenses
- H01S 5/04256: {characterised by the configuration}
- H01S 5/1039: {Details on the cavity length}
- H01S 5/305: {characterised by the doping materials used in the laser structure}
- H01S 5/3063: {using Mg}
- H01S 5/32025: {non-polar orientation}
- H01S 5/3215: {graded composition cladding layers}
- H01S 5/34: comprising quantum well or superlattice structures, e.g. single quantum well [SQW] lasers, multiple quantum well [MQW] lasers or graded index separate confinement heterostructure [GRINSCH] lasers (H01S5/36 takes precedence)
- H01S 5/34333: {with a well layer based on Ga(In)N or Ga(In)P, e.g. blue laser}
- H01S 2301/176: Specific passivation layers on surfaces other than the emission facet
- H01S 2304/04: MOCVD or MOVPE
- 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 object of the present invention is to provide a method for manufacturing an optical device having a laser diode, which method is suitable for mass production, and an optical device having a laser diode which allows accurate property evaluations thereof with small measurement errors. Specifically, the method includes: an etching process of etching a semiconductor lamination unit to form a mesa structure having a resonator end face, thereby forming a laser diode; and a reflecting layer forming process of forming a light reflecting layer such that the light reflecting layer covers entire side surfaces of the mesa structure, wherein the semiconductor lamination unit has a substate, a n-type clad layer including a nitride semiconductor layer having n-type conductivity, a light-emitting layer including at least one quantum well, and a p-type clad layer including a nitride semiconductor layer having p-type conductivity, laminated in this order.

## Claims

### Claim 1

An optical device having a laser diode, wherein the laser diode comprises:
a substrate;
a n-type clad layer formed on the substrate and including a nitride semiconductor layer having n-type conductivity;
a light-emitting layer formed on the n-type clad layer and including at least one quantum well;
a p-type clad layer formed on the light-emitting layer and including a nitride semiconductor layer having p-type conductivity, and
a photodetector formed on the substrate, having a mesa structure and capable of receiving and detecting light emitted from the laser diode,
wherein at least a portion of the n-type clad layer, the light-emitting layer and the p-type clad layer constitute a mesa structure having a resonator end face, and entire side surfaces of the mesa structure are covered with a light reflecting layer,
wherein all side surfaces of the mesa structure of the photodetector are covered with the light reflecting layer, and
where a light reflectance of the light reflecting layer is 50% or more with respect to a desired wavelength.

### Claim 2 (depends on 1)

The optical device of claim 1, wherein a laser beam receiving face of the photodetector is positioned to be opposed to a main laser beam emitting face of the laser diode.

### Claim 3 (depends on 1)

The optical device of claim 1, comprising a plurality of the laser diodes.

### Claim 4 (depends on 1)

The optical device of claim 1, wherein the p-type clad layer includes: a p-type longitudinally conductive layer containing AlsGa1-sN(0.3≤s≤1), having film thickness smaller than 0.5 μm and a graded Al composition “s” which decreases in the direction away from the top surface of the substrate; and a p-type transversely conductive layer composed of AltGa1-tN(0<t≤1).

### Claim 5 (depends on 1)

The optical device of claim 1, wherein the light reflecting layer is a dielectric lamination film.

### Claim 6 (depends on 1)

The optical device of claim 1, wherein the light reflecting layer is made of oxide of at least one selected from the group consisting of aluminum, hafnium, silicon, titanium, zirconium, lead, and gallium.

### Claim 7 (depends on 5)

The optical device of claim 5, wherein the dielectric lamination film is a lamination film in which a hafnium oxide film and an aluminum oxide film are laminated at ≥1 lamination cycle.

### Claim 8 (depends on 1)

The optical device of claim 1, wherein the substrate is an AlN substrate and an angle formed by a surface adjacent to the resonator end face, of the light reflecting layer, with respect to the (0001) plane of the AlN substrate is in the range of ≥85° and ≤95°.

### Claim 9 (depends on 1)

The optical device of claim 1, wherein the n-type clad layer, the light-emitting layer and the p-type clad layer are AlGaN layers and the (1-100) plane of the AlGaN layers constitutes the resonator end face.