A high-power low-divergence semiconductor laser chip

Abstract

The present invention relates to a high-power, low-divergence semiconductor laser chip, belonging to the field of semiconductor lasers. The stacked structure includes, from bottom to top, an N-face metal, a substrate, an N-type confinement layer, an N-type waveguide layer, a quantum well layer, a P-type waveguide layer, a P-type confinement layer, an insulating layer, and a P-face metal. A ridge waveguide extends along the light output direction of the laser chip, and is wide at both ends and narrow in the middle. A current injection region is formed on the ridge waveguide, an isolation groove region is formed in the ridge waveguide near the cavity surface and in the regions on both sides, and deep trench regions are formed on both sides of the ridge waveguide. The deep trench regions are triangular in the light output direction and wide near the cavity surface. The present invention can effectively eliminate the thermal lens effect and greatly reduce the slow-axis divergence angle. At the same time, the ridge waveguide adopts a wide-end configuration, which reduces the carrier accumulation effect at the edge of the ridge waveguide, eliminates the high-power peaks in the edge region of the near-field light spot, avoids damage to the cavity surface caused by excessive local light field intensity, and greatly improves the long-term reliability of the device.

Description

Technical Field

[0001] The invention relates to a high-power low-divergence-angle semiconductor laser chip, belonging to the technical field of semiconductor lasers. Background Art

[0002] Wide-stripe high-power semiconductor lasers have been continuously developed due to their high output power, simple preparation process, simple packaging process, and easy integration and mass production. They have been widely used in laser cutting, medical cosmetology, and industrial pumping. Usually, wide-stripe high-power semiconductor lasers use a ridge stripe process. The current enters the active region through the ridge stripe and undergoes radiation recombination to generate photons. However, with the continuous development of industries and other fields, higher requirements are placed on the beam quality of wide-stripe lasers. However, since the ridge structure belongs to a waveguide structure, it is used to limit carriers and light fields. However, when limiting the light field, there are the following technical problems: 1. There are strong power peaks at the edge of the near-field light spot, which can easily cause irreversible COD problems. 2. There is a more serious thermal lens effect, resulting in a larger slow axis divergence angle. Summary of the Invention

[0003] In response to the shortcomings of the existing technology, the present invention provides a high-power, low-divergence-angle semiconductor laser chip, which can effectively eliminate the thermal lens effect and greatly reduce the slow-axis divergence angle. At the same time, the ridge waveguide adopts a wide-at-two-end configuration, which reduces the carrier accumulation effect at the edge of the ridge waveguide, eliminates the high-power peaks in the edge area of the near-field light spot, avoids damage to the cavity surface caused by excessive local light field, and greatly improves the long-term reliability of the device.

[0004] The present invention adopts the following technical solutions:

[0005] A high-power low-divergence-angle semiconductor laser chip comprises a stacked structure, a ridge waveguide, a current injection region, an isolation groove region and a deep trench region;

[0006] The stacked structure includes an N-side metal, a substrate, an N-type confinement layer, an N-type waveguide layer, a quantum well layer, a P-type waveguide layer, a P-type confinement layer, an insulating layer and a P-side metal, which are arranged in sequence from bottom to top;

[0007] The ridge waveguide extends along the light-emitting direction of the semiconductor laser chip. The light-emitting direction is the extension direction of the cavity length of the semiconductor laser chip. The ridge waveguide tends to be wide at both ends and narrow in the middle.

[0008] The ridge waveguide is wide near the cavity surface and narrow near the center. Because the current is injected through the current injection area, the wide ends will reduce the current density at both ends due to expansion, and thus the current density at the edge is low, thereby eliminating the accumulation effect of carriers at the edge of the ridge waveguide, eliminating the high power peaks in the edge area of the near-field light spot, and avoiding damage to the cavity surface caused by excessive local light field.

[0009] The current injection area is formed on the ridge waveguide, and the isolation groove area is formed on the ridge waveguide near the cavity surface and the areas on both sides of it, which reduces the current injection at the cavity surface, thereby reducing the heat at the cavity surface and effectively increasing the maximum power density allowed by the cavity surface; the deep groove area is formed on both sides of the ridge waveguide, which is triangular in the light output direction and has a large width near the cavity surface. This is the optimal shape obtained through simulation. Through this shape, the thermal lens effect can be effectively eliminated.

[0010] The insulating layer is grown using PECVD after etching the ridge waveguide and deep trench area, and then the insulating layer in the current injection area is etched away to form the current injection area. This is a conventional process in semiconductor laser technology.

[0011] The present invention can overcome the defect of light field limitation in the prior art and solve the reliability problem of semiconductor devices when large current is injected.

[0012] Furthermore, the width s1 of the current injection region is smaller than the minimum width of the ridge waveguide, and the width direction thereof is parallel to the cavity surface of the semiconductor laser chip.

[0013] Furthermore, the isolation groove area can be obtained by photolithography and etching, and its width s3 is greater than the maximum width s2 of the ridge waveguide. At the same time, the distance d1 between the isolation groove area close to the light-emitting cavity surface and the light-emitting cavity surface is greater than the distance d2 between the isolation groove area on the non-light-emitting cavity surface and the non-light-emitting cavity surface, which can completely isolate the current from passing through the cavity surface.

[0014] Furthermore, the ridge waveguide is prepared by a wet etching process, and all non-ridge waveguide areas are removed by etching.

[0015] Furthermore, the length L2 of the current injection region in the light emitting direction is smaller than the length L1 of the ridge waveguide.

[0016] Furthermore, the deep trench region is obtained by photolithography and etching, and the etching depth of the deep trench region completely penetrates the N-type confinement layer.

[0017] Where the present invention is not exhaustive, existing technologies may be used.

[0018] The beneficial effects of the present invention are:

[0019] 1. The semiconductor laser chip provided by the present invention is prepared by preparing a deep trench area. Since there is no metal growth in the deep trench, cavities will form there during packaging. The cavities will reduce the heat dissipation efficiency, thereby reducing the heat dissipation efficiency of the area, ultimately making the temperature distribution on the ridge waveguide uniform, thereby effectively eliminating the thermal lens effect and greatly reducing the slow axis divergence angle. At the same time, the ridge waveguide adopts a wide-at-two-end shape, which reduces the carrier accumulation effect at the edge of the ridge waveguide, eliminates the high-power peaks in the edge area of the near-field light spot, avoids damage to the cavity surface caused by excessive local light field, and greatly improves the long-term reliability of the device.

[0020] 2. The present invention does not change the subsequent packaging process, and conventional packaging methods can be used subsequently, which improves chip performance while ensuring chip production efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings, which constitute a part of the present invention, are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute improper limitations on the present invention.

[0022] Figure 1 Schematic diagram of the cross section of a high-power low-divergence semiconductor laser chip;

[0023] Figure 2 This is a top view of the P surface of a high-power, low-divergence semiconductor laser chip;

[0024] In the figure: 1-P-side metal, 2-insulating layer, 3-P-type confinement layer, 4-P-type waveguide layer, 5-quantum well layer, 6-N-type waveguide layer, 7-N-type confinement layer, 8-substrate, 9-N-side metal, 10-ridge waveguide, 11-deep trench region, 12-current injection region, 13-isolation trench region. DETAILED DESCRIPTION

[0025] In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, they will be described in detail below with reference to the accompanying drawings and specific embodiments, but are not limited thereto. Matters not fully described in the present invention shall be based on conventional techniques in the art.

[0026] Example 1

[0027] A high-power low-divergence-angle semiconductor laser chip includes a stacked structure, a ridge waveguide 10, a current injection region 12, an isolation groove region 13, and a deep trench region 11;

[0028] The stacked structure includes, from bottom to top, an N-side metal 9, a substrate 8, an N-type confinement layer 7, an N-type waveguide layer 6, a quantum well layer 5, a P-type waveguide layer 4, a P-type confinement layer 3, an insulating layer 2, and a P-side metal 1;

[0029] The ridge waveguide 10 extends along the light emitting direction of the semiconductor laser chip. The light emitting direction is the extension direction of the cavity length of the semiconductor laser chip. The ridge waveguide has a trend of being wide at both ends and narrow in the middle.

[0030] The ridge waveguide is wide near the cavity surface and narrow near the center. Because the current is injected through the current injection area, the wide ends will reduce the current density at both ends due to expansion, and thus the current density at the edge is low, thereby eliminating the accumulation effect of carriers at the edge of the ridge waveguide, eliminating the high power peaks in the edge area of the near-field light spot, and avoiding damage to the cavity surface caused by excessive local light field.

[0031] A current injection region 12 is formed on the ridge waveguide, and an isolation groove region 13 is formed on the ridge waveguide near the cavity surface and on both sides thereof, thereby reducing current injection at the cavity surface, thereby reducing heat generation at the cavity surface and effectively increasing the maximum power density allowed by the cavity surface; deep groove regions 11 are formed on both sides of the ridge waveguide, which are triangular in the light-emitting direction and have a large width near the cavity surface. This is the optimal shape obtained through simulation, and this shape can effectively eliminate the thermal lens effect.

[0032] The insulating layer 2 is grown by PECVD after etching the ridge waveguide and deep trench area, and then the insulating layer in the current injection area is etched away to form the current injection area. This is a conventional process in semiconductor laser technology.

[0033] The present invention can overcome the defect of light field limitation in the prior art and solve the reliability problem of semiconductor devices when large current is injected.

[0034] Example 2

[0035] A high-power low divergence angle semiconductor laser chip is as described in Example 1, except that the width s1 of the current injection region 12 is smaller than the minimum width of the ridge waveguide, and its width direction is parallel to the direction of the semiconductor laser chip cavity surface.

[0036] Example 3

[0037] A high-power, low-divergence-angle semiconductor laser chip, as described in Example 1, except that the isolation groove region 13 can be obtained by photolithography and etching, and its width s3 is greater than the maximum width s2 of the ridge waveguide. At the same time, the distance d1 between the isolation groove region near the light-emitting cavity surface and the light-emitting cavity surface is greater than the distance d2 between the isolation groove region on the non-light-emitting cavity surface and the non-light-emitting cavity surface, thereby completely isolating the current from passing through the cavity surface.

[0038] Example 4

[0039] A high-power, low-divergence-angle semiconductor laser chip is as described in Example 1, except that the ridge waveguide 10 is prepared by a wet etching process, and all non-ridge waveguide regions are removed by etching.

[0040] The length L2 of the current injection region 12 in the light emitting direction is smaller than the length L1 of the ridge waveguide.

[0041] The deep trench region 11 is obtained by photolithography and etching, and the etching depth of the deep trench region completely penetrates the N-type confinement layer.

[0042] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-power low-divergence semiconductor laser chip, characterized in that: It includes a stacked structure, a ridge waveguide, a current injection region, an isolation groove region and a deep trench region; The stacked structure includes an N-side metal, a substrate, an N-type confinement layer, an N-type waveguide layer, a quantum well layer, a P-type waveguide layer, a P-type confinement layer, an insulating layer and a P-side metal, which are arranged in sequence from bottom to top; The ridge waveguide extends along the light emitting direction of the semiconductor laser chip. The light emitting direction is the extension direction of the cavity length of the semiconductor laser chip. The ridge waveguide is wide at both ends and narrow in the middle. The current injection region is formed on the ridge waveguide, the isolation groove region is formed on the ridge waveguide and the areas on both sides thereof near the cavity surface, and the deep groove region is formed on both sides of the ridge waveguide. It is triangular in the light emitting direction and has a large width near the cavity surface.

2. The high-power low divergence angle semiconductor laser chip according to claim 1, characterized in that: The width s1 of the current injection region is smaller than the minimum width of the ridge waveguide, and the width direction is parallel to the cavity surface of the semiconductor laser chip.

3. The high-power low divergence angle semiconductor laser chip according to claim 2, characterized in that: The width s3 of the isolation groove region is greater than the maximum width s2 of the ridge waveguide. At the same time, the distance d1 between the isolation groove region close to the light output cavity surface and the light output cavity surface is greater than the distance d2 between the isolation groove region on the non-light output cavity surface and the non-light output cavity surface.

4. The high-power low divergence angle semiconductor laser chip according to claim 3, characterized in that: The ridge waveguide is prepared by a wet etching process, and all non-ridge waveguide areas are removed by etching.

5. The high-power low divergence angle semiconductor laser chip according to claim 4, characterized in that: The length L2 of the current injection region in the light-emitting direction is smaller than the length L1 of the ridge waveguide.

6. The high-power low divergence angle semiconductor laser chip according to claim 5, characterized in that: The etching depth of the deep trench region completely penetrates the N-type confinement layer.

Images