# US 5,348,912 A · Semiconductor surface emitting laser having enhanced optical confinement

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- Number: US 5,348,912 A
- Document ID: US5348912A
- Status: Granted
- Kind: A
- Application number: 08/016,339
- Filed: 1993-02-11
- Granted: 1994-09-20
- Earliest claimed: 1992-03-25
- Assignees: AT&T Bell Laboratories
- Inventors: Kent D. Choquette; Robert S. Freund; Minghwei Hong
- Web page: https://patentgrep.com/patent/US5348912A

## CPC

- H01S 5/18308: {having a special structure for lateral current or light confinement}
- H01S 5/0283: {Optically inactive coating on the facet, e.g. half-wave coating}
- H01S 5/222: {having a refractive index lower than that of the cladding layers or outer guiding layers}
- H01S 5/2222: {having special electric properties}
- 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 present applicants have discovered that one can make a surface emitting laser with enhanced optical confinement and improved heat sinking characteristics by etching away portions of the growth layers peripheral to the intended laser cavity and regrowing peripheral regions of material having a lower index of refraction than the active region. Using low damage etching and either in situ regrowth or hydrogen plasma cleaning followed by regrowth, a surface emitting laser having enhanced optical isolation and heat sinking characteristics can be made.

## Claims

### Claim 1

A method for making a semiconductor surface emitting laser comprising the steps of:
providing a semiconductor substrate;
growing on said substrate the layers comprising an inner reflecting stack, an active layer and an outer reflecting stack;
at reduced pressure etching away portions of said outer stack and said active layer peripherally surrounding a desired active region; and
without exposing the etched substrate to atmosphere and at reduced pressure, epitaxially regrowing in the etched away region peripherally surrounding said active region, a material having an index of refraction lower than that of said active region.

### Claim 2

A method for making a semiconductor surface emitting laser comprising the steps of:
providing a semiconductor substrate;
growing on said workpiece the layers comprising an inner reflecting stack; an active layer and an outer reflecting stack;
etching away portions of said outer stack and said active layer peripherally surrounding a desired active region;
exposing the etched substrate to gas plasma comprising hydrogen: and
without exposing the plasma processed workpiece to atmosphere and at reduced pressure, regrowing in the etched away region surrounding said active region, a material having an index of refraction lower than that of said active region.

### Claim 3 (depends on 1)

The method of claim 1, wherein said semiconductor substrate comprises gallium arsenide, said inner reflecting stack comprises aluminum gallium arsenide, said outer reflecting stack comprises aluminum gallium arsenide and said epitaxially regrown material comprises aluminum gallium arsenide.

### Claim 4 (depends on 2)

The method of claim 2, wherein said semiconductor substrate comprises gallium arsenide, said inner reflecting stack comprises aluminum gallium arsenide, said outer reflecting stack comprises aluminum gallium arsenide and said epitaxially regrown material comprises aluminum gallium arsenide.