# US 12,119,620 B2 · Edge emitting laser diode and method for producing same

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- Number: US 12,119,620 B2
- Document ID: US12119620B2
- Status: Granted
- Kind: B2
- Application number: 17/430,658
- Filed: 2020-01-16
- Published: 2022-04-21
- Granted: 2024-10-15
- Earliest claimed: 2019-02-15
- Assignees: OSRAM Opto Semiconductors GmbH
- Applicants: OSRAM Opto Semiconductors GmbH
- Inventors: Jens Ebbecke
- Web page: https://patentgrep.com/patent/US12119620B2

## CPC

- H01S 5/04252: {characterised by the material}
- H01S 5/4043: {with vertically stacked active layers}
- H01S 5/02461: {Structure or details of the laser chip to manipulate the heat flow, e.g. passive layers in the chip with a low heat conductivity}
- H01S 5/0282: {Passivation layers or treatments}
- H01S 5/0287: {Facet reflectivity}
- H01S 5/2036: {Broad area lasers}
- H01S 5/2218: {having special optical properties}
- H01S 5/3201: {incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation}
- H01S 5/04254: {characterised by the shape}
- H01S 5/222: {having a refractive index lower than that of the cladding layers or outer guiding layers}
- H01S 2301/18: Semiconductor lasers with special structural design for influencing the near- or far-field
- 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

The invention relates to an edge emitting laser diode comprising a semiconductor layer stack whose growth direction defines a vertical direction, and wherein the semiconductor layer stack comprises an active layer and a waveguide layer. A thermal stress element is arranged in at least indirect contact with the semiconductor layer stack, the thermal stress element being configured to generate a thermally induced mechanical stress in the waveguide layer that counteracts the formation of a thermal lens.

## Claims

### Claim 1

An edge emitting laser diode comprising:
a semiconductor layer stack whose growth direction defines a vertical direction; and
wherein the semiconductor layer stack comprises an active layer and a waveguide layer;
characterized in that
a thermal stress element is arranged in at least indirect contact with the semiconductor layer stack;
wherein the thermal stress element is configured for generating a thermally induced mechanical stress in the waveguide layer which counteracts the formation of a thermal lens,
wherein the thermal stress element consists of a material with a thermal expansion coefficient αth which is smaller than 0.5*10−6 K−1 in a temperature range from 20° C. to 300° C., and
wherein the thermal stress element is arranged such that it adjoins a region of the waveguide for which, during operation of the laser diode, the greatest temperature gradient is present as a function of the lateral direction.

### Claim 2 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the thermal stress element is arranged in the vertical direction above the active layer and/or in a lateral direction perpendicular to the vertical direction next to the active layer in or adjacent to the semiconductor layer stack.

### Claim 3 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the thermal stress element consists of a material with a negative thermal expansion coefficient αth in the temperature range from 20° C. to 300° C.

### Claim 4 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the thermal stress element contains an oxide compound of zirconium and tungsten.

### Claim 5 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the thermal stress element contains aluminum titanate and/or zirconium titanate.

### Claim 6 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the thermal stress element is part of a passivation layer of the semiconductor layer stack or is formed by a structured passivation layer.

### Claim 7 (depends on 1)

The edge emitting laser diode according to claim 1, wherein the edge emitting laser diode is a broad area laser diode.

### Claim 8 (depends on 7)

The edge emitting laser diode according to claim 7, wherein the broad area laser diode comprises an optical resonator having a mirror facet and an exit facet arranged spaced from each other in a longitudinal direction, wherein the longitudinal direction forms an orthogonal tripod with the vertical direction and a lateral direction; and wherein at least in a partial section of the optical resonator the extension of the thermal stress element in the vertical direction and/or in the lateral direction increases with decreasing distance from the exit facet.

### Claim 9

A method for manufacturing an edge emitting laser diode, comprising:
manufacturing a semiconductor layer stack, wherein the growth direction of the semiconductor layer stack defines a vertical direction; and
wherein an active layer and a waveguide layer are provided in the semiconductor layer stack;
characterized in that
a thermal stress element is arranged such that it adjoins a region of the waveguide for which, during operation of the laser diode, the greatest temperature gradient is present as a function of the lateral direction such that
the thermal stress element generates a thermally induced mechanical stress in the waveguide layer during operation of the laser diode, which stress counteracts the formation of a thermal lens,
wherein the thermal stress element is made of a material having a coefficient of thermal expansion αth which is smaller than 0.5*10−6 K−1 in a temperature range from 20° C. to 300° C.

### Claim 10 (depends on 9)

The method for manufacturing a laser diode according to claim 9, wherein the thermal stress element is arranged in the vertical direction above the active layer and/or in a lateral direction perpendicular to the vertical direction next to the active layer in or adjacent to the semiconductor layer stack.

### Claim 11 (depends on 9)

The method for manufacturing an edge emitting laser diode according to claim 9, wherein the thermal stress element is made of a material having a negative coefficient of thermal expansion αth in the temperature range from 20° C. to 300° C.