# US 2020/0403379 A1 · Vertical cavity surface emitting laser diode (vcsel) with multiple current confinement layers

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- Number: US 2020/0403379 A1
- Document ID: US20200403379A1
- Status: Published application
- Kind: A1
- Application number: 16/906,067
- Filed: 2020-06-19
- Published: 2020-12-24
- Earliest claimed: 2019-06-21
- Assignees: Visual Photonics Epitaxy Co., Ltd.
- Applicants: Visual Photonics Epitaxy Co., Ltd.
- Inventors: Chao-Hsing Huang; Yu-Chung Chin; Van-Truong Dai
- Web page: https://patentgrep.com/patent/US20200403379A1

## CPC

- H01S 5/1833: {with more than one structure}
- H01S 5/18311: {using selective oxidation}
- H01S 5/18383: {with periodic active regions at nodes or maxima of light intensity}
- H01S 5/3095: {Tunnel junction}
- H01S 5/0014: {Measuring characteristics or properties thereof (measuring techniques per se G01J, G01K, G01N, G01R)}
- H01S 5/18305: {with emission through the substrate, i.e. bottom emission}
- H01S 5/18358: {containing spacer layers to adjust the phase of the light wave in the cavity}
- 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

Provided is a vertical cavity surface emitting laser diode (VCSEL) with multiple current confinement layers. A tunnel junction is generally required between two active layers to enable current to flow from one to another active layer. However, the tunnel junction will cause the current to spread in one active layer to become serious. As a result, the current in another active layer is difficult to be confined to the required area. Therefore, a current confinement layer with carrier and optical confinement functions is provided between two active layers such that the carrier and optical confinement of the active layers above and below the current confinement layer can be improved, thereby improving the performance of VCSEL. Compared with the existing VCSEL, the VCSEL with multiple current confinement layers can significantly improve the optical output power, slope efficiency and power conversion efficiency (PCE) of the VCSEL.

## Claims

### Claim 1

A vertical cavity surface emitting laser diode (VCSEL), comprising:
a multi-layer structure on a substrate, wherein the multi-layer structure comprises:
an active region, comprising a plurality of active layers, wherein a tunnel junction is provided between two active layers; and
a plurality of current confinement layers, at least comprising a first current confinement layer and a second current confinement layer, wherein the first current confinement layer at least has a first optical aperture (OA), the second current confinement layer at least has a second OA, the first OA and the second OA are uninsulated portions of each of the plurality of current confinement layers, one of the first OA and the second OA is disposed outside the active region, the other of the first OA and the second OA is disposed inside the active region, and the tunnel junction is positioned between the first OA and the second OA.

### Claim 2 (depends on 1)

The VCSEL as claimed in claim 1, wherein the insulated portions of both the first current confinement layer and the second current confinement layer are made by an insulation process, and the insulation process is an oxidation process, an ion implantation process or an etching process.

### Claim 3 (depends on 1)

The VCSEL as claimed in claim 1, wherein the first current confinement layer and/or the second current confinement layer is/are selected from the group consisting of AlGaAs, AlGaAsP, AlAs, AlAsP, AlAsSb and AlAsBi.

### Claim 4 (depends on 1)

The VCSEL as claimed in claim 1, wherein one of the first current confinement layer and the second current confinement layer is disposed above or below the active region, and the other of the first current confinement layer and the second current confinement layer is disposed inside the active region.

### Claim 5 (depends on 1)

The VCSEL as claimed in claim 1, wherein an area of the first OA is not equal to an area of the second OA.

### Claim 6 (depends on 5)

The VCSEL as claimed in claim 5, wherein a ratio of the area of the first OA to the area of the second OA is approximately between 0.2 and 5.

### Claim 7 (depends on 5)

The VCSEL as claimed in claim 5, wherein a ratio of the area of the first OA to the area of the second OA is approximately between 0.3 and 3.3.

### Claim 8 (depends on 5)

The VCSEL as claimed in claim 5, wherein a ratio of the area of the first OA to the area of the second OA is approximately between 0.5 and 2.

### Claim 9 (depends on 1)

The VCSEL as claimed in claim 1, wherein an area of the first OA is approximately equal to an area of the second OA.

### Claim 10 (depends on 9)

The VCSEL as claimed in claim 9, wherein the areas of the first OA and the second OA are greater than 30 μm2.

### Claim 11 (depends on 9)

The VCSEL as claimed in claim 9, wherein the areas of the first OA and the second OA are greater than 40 μm2.

### Claim 12 (depends on 9)

The VCSEL as claimed in claim 9, wherein the areas of the first OA and the second OA are greater than 50 μm2.

### Claim 13 (depends on 1)

The VCSEL as claimed in claim 1, wherein the VCSEL is a top-emitting VCSEL or a bottom-emitting VCSEL.

### Claim 14

A vertical cavity surface emitting laser diode (VCSEL), comprising:
a multi-layer structure on a substrate, wherein the multi-layer structure comprises:
an active region, comprising three or more active layers, wherein a tunnel junction is provided between every two adjacent ones of the active layers; and
a plurality of current confinement layers, at least comprising a first current confinement layer, a second current confinement layer and a third current confinement layer, wherein, the first current confinement layer at least has a first optical aperture (OA), the second current confinement layer at least has a second OA, the third current confinement layer at least has a third OA, the first OA, the second OA and the third OA are uninsulated portions of each of the plurality of current confinement layers, wherein one of the first OA, the second OA and the third OA is disposed outside the active region, and another of the first OA, the second OA and the third OA is disposed inside the active region, and the other of the first OA, the second OA and the third OA is disposed inside or outside the active region, the tunnel junction is positioned between the first OA and the second OA or between the second OA and the third OA.

### Claim 15 (depends on 14)

The VCSEL as claimed in claim 14, wherein a number of the plurality of current confinement layers is three, four, five or more.

### Claim 16 (depends on 14)

The VCSEL as claimed in claim 14, wherein a number of the plurality of current confinement layers is the same as or more than a number of active layers.

### Claim 17 (depends on 14)

The VCSEL as claimed in claim 14, wherein one of the plurality of current confinement layers is disposed above or below the active region, and the others thereof are disposed inside the active region.

### Claim 18 (depends on 14)

The VCSEL as claimed in claim 14, wherein when two of the first current confinement layer, the second current confinement layer and the third current confinement layer are disposed outside the active region, the active region is positioned between the two of the first current confinement layer, the second current confinement layer and the third current confinement layer.

### Claim 19 (depends on 14)

The VCSEL as claimed in claim 14, wherein one of the plurality of current confinement layers is selected from the group consisting of AlGaAs, AlGaAsP, AlAs, AlAsP, AlAsSb and AlAsBi.

### Claim 20 (depends on 14)

The VCSEL as claimed in claim 14, wherein areas of two of the first OA, the second OA and the third OA are not equal.

### Claim 21 (depends on 20)

The VCSEL as claimed in claim 20, wherein a ratio of the areas of two of the first OA, the second OA and the third OA is approximately between 0.2 and 5.

### Claim 22 (depends on 20)

The VCSEL as claimed in claim 20, wherein a ratio of the areas of two of the first OA, the second OA and the third OA is approximately between 0.3 and 3.3.

### Claim 23 (depends on 20)

The VCSEL as claimed in claim 20, wherein a ratio of the areas of two of the first OA, the second OA and the third OA is approximately between 0.5 and 2.

### Claim 24 (depends on 14)

The VCSEL as claimed in claim 14, wherein areas of two of the first OA, the second OA and the third OA are approximately equal.

### Claim 25 (depends on 24)

The VCSEL as claimed in claim 24, wherein the areas of the first OA, the second OA and the third OA are greater than 30 μm2.

### Claim 26 (depends on 24)

The VCSEL as claimed in claim 24, wherein the areas of the first OA, the second OA and the third OA are greater than 40 μm2.

### Claim 27 (depends on 24)

The VCSEL as claimed in claim 24, wherein the areas of the first OA, the second OA and the third OA are greater than 50 μm2.

### Claim 28 (depends on 14)

The VCSEL as claimed in claim 14, wherein the VCSEL is a top-emitting VCSEL or a bottom-emitting VCSEL.