Array of Surface-Emitting Lasers with High-Brightness Unipolar Output

Patent metadata

Field	Value
Publication number	US-2021336423-A1
Application number	US-202017025214-A
Country	US
Kind code	A1
Filing date	Sep 18, 2020
Priority date	Apr 28, 2020
Publication date	Oct 28, 2021
Grant date	—

Abstract

An array of surface-emitting lasers is provided. The array outputs high brightness in a unipolar way. The array comprises a stress-adjustment unit and a plurality of epitaxial device units. The stress-adjustment unit is used to adjust stress. The stress from a substrate is used to select a laser mode for an aperture unit. The selection of the laser mode is enhanced for the aperture unit without sacrificing driving current. Low current operation is achieved in a single mode for effectively reducing volume and further minimizing the size of the whole array to achieve high-quality laser output. An object can be scanned by the outputted laser to obtain a clear image with a high resolution. Hence, the present invention is applicable for face recognition with high recognition and high security.

First claim

What is claimed is:

1 . An array of surface-emitting lasers with high-brightness unipolar output, comprising
a stress-adjustment unit,
wherein said stress-adjustment unit comprises a copper layer and an epitaxial layer stacked on said copper layer; said stress-adjustment unit obtains a stress adjustable to single-polarize the stress for enhancing selectivity of an aperture to a laser mode driving current is not sacrificed while obtaining a single-mode and low-current operation; and
a plurality of epitaxial device units,
wherein each one of said epitaxial device units is stacked on said stress-adjustment unit and comprises a first distributed Bragg reflector (DBR); an active region stacked on said first DBR; and a second DBR stacked on said active region; said active region has a current-confining aperture; said current-confining aperture is deposed in a grouping at a position selected from a group consisting of a position above said active region and a position beneath said active region; said current-confining aperture obtains a current confinement zone through a method selected from a group consisting of oxidation and indentation at an annular lateral part of an aluminum (Al) composite layer; and and the Al composite layer contains Al, a Ill element, more than 20 percent (%). where said second DBR contains a diffusion unit having a thickness reduced to 0.1˜2 micrometers (μm); said diffusion unit is located around an annular area on top of said second DBR with a multilayer of different compositions selectively disordered through a doping diffusion process to obtain a single layer of single composition; and said second DBR is thus enabled to control a sum number of optical modes.

2 . The array according to claim 1 ,
wherein said stress is selected from a group consisting of a compressive stress and a tensile stress.

3 . The array according to claim 1 ,
wherein said copper layer has a thickness between 50 μm and 1 millimeter (mm).

4 . The array according to claim 1 ,
wherein said epitaxial layer has a thickness smaller than 10 μm±20%.

5 . The array according to claim 1 ,
wherein between said copper layer and said epitaxial layer, the array further comprises a gold layer stacked on said copper layer and a substrate stacked between said gold layer and said epitaxial layer.

6 . The array according to claim 5 ,
wherein said substrate is of a semiconductor selected from a P-type semiconductor, an N-type semiconductor and a semi-insulating semiconductor, having a thickness of 100˜200 μm.

7 . The array according to claim 6 ,
wherein said semi-insulating semiconductor is of gallium arsenide (GaAs).

8 . The array according to claim 1 ,
wherein between said copper layer and said epitaxial layer, the array further comprises a plurality of substrates interleaved with said epitaxial device units.

9 . The array according to claim 1 ,
wherein said first DBR is an n-type DBR (n-DBR) and said second DBR is a p-type DBR (p-DBR).

10 . The array according to claim 1 ,
wherein said first DBR is a p-DBR and said second DBR is an n-DBR.

11 . The array according to claim 1 ,
wherein said Al composite layer is partially converted to an oxide layer with center area remained unchanged and an etchant is obtained to process a selective etching to remove said oxide layer to obtain said current-confining aperture and said current confinement zone.

12 . The array according to claim 1 ,
wherein said current confinement zone is an annular zone having a diameter smaller than 20 μm.

13 . The array according to claim 1 ,
wherein said active region is a heterojunction of a compound semiconductor and an alloy thereof.

14 . The array according to claim 13 ,
wherein said active region is a heterojunction of indium aluminum gallium arsenide/aluminum gallium arsenide (InAlGaAs/AlGaAs).

15 . The array according to claim 1 ,
wherein said active region is a multiple-quantum-wells (MQWs) region of three InAlGaAs/AlGaAs interposed between said first DBR and said second DBR obtained through epitaxial growth.

16 . The array according to claim 1 ,
wherein a lateral side of a total of said second DBR, said active region, and a part of said first DBR is surrounded by an insulating layer.

17 . The array according to claim 1 ,
wherein said diffusion unit has a diameter of 5˜20 μm.

18 . The array according to claim 1 ,
wherein said diffusion unit located around said annular area on top of said second DBR is obtained through said doping diffusion process of an element selected from a group consisting of a II element, a IV element, and a VI element; and, around said center area on top of said second DBR, said multilayer of different compositions is selectively disordered to form the single layer of single composition.

19 . The array according to claim 1 ,
wherein said diffusion unit located around said annular area on top of said second DBR is obtained through said doping diffusion process of doping an element selected from a group consisting of zinc (Zn) and magnesium (Mg); and, around said center area on top of said second DBR, said multilayer of different compositions is selectively disordered to form the single layer of single composition.

20 . The array according to claim 1 ,
wherein said diffusion unit located around said annular area on top of said second DBR is located above said active region and is not in contact with said active region.

Assignees

• Univ Nat Central

Inventors

• Shi Jin-Wei

Classifications

• H01S5/18355 Primary

  having a defined polarisation · CPC title

• H01S5/183

  having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL] · CPC title

• H01S5/42 Primary

  Arrays of surface emitting lasers · CPC title

• H01S5/3201

  incorporating bulkstrain effects, e.g. strain compensation, strain related to polarisation · CPC title

• H01S5/34353

  based on (AI)GaAs · CPC title