A single-mode high-power edge-emitting laser and its preparation method

Abstract

The present application relates to the technical field of lasers, and in particular to a single-mode high-power edge-emitting laser and a preparation method thereof, comprising a P-face structural layer, an active region, and an N-face structural layer, wherein the P-face structural layer is provided with a single-mode filter region, the single-mode filter region is provided with single-mode enhancement regions on both sides in the horizontal lateral direction, the single-mode enhancement region is provided with high-order mode coupling regions on both sides in the horizontal and vertical directions, the single-mode enhancement region is provided with a single-mode amplification region on the side away from the single-mode filter region, and the P-face structural layer is provided with an opening that passes through the single-mode filter region, the single-mode enhancement region, and the single-mode amplification region. The single-mode amplification region can increase the gain to amplify the single-mode power, which is equivalent to a single-mode power amplification structure. Because of the lateral size restrictions of the single-mode filter region and the single-mode enhancement region and the mode filtering function, there is no need to worry about high-order mode lasing.

Description

Technical Field

[0001] The present application relates to the technical field of lasers, and in particular to a single-mode high-power edge-emitting laser and a preparation method thereof. Background Art

[0002] As a core branch of semiconductor lasers, single-mode lasers have made significant progress in technological breakthroughs, application expansion, and market growth in recent years. For example, the 1550nm InGaAsP / InP DFB laser supports a 40GbPs transmission rate and is used in 40km long-distance fiber-optic communications; autonomous driving is driving demand for 905nm / 1550nm single-mode lasers, high-power single-mode lasers (kilowatt-level) are used for precision cutting and welding, and blue light (450nm) lasers are used in the medical field for ophthalmic surgery.

[0003] Traditional approaches to achieving single-mode output rely on limiting the waveguide width and optimizing carrier distribution to suppress high-order mode oscillations, or using two-dimensional photonic crystals or DFB structures to confine high-order transverse modes. However, these approaches suffer from limitations in mode stability and reliability. For example, mode hopping can occur during high-temperature and high-power operation, or excessive power density at the cavity surface can lead to chip reliability issues that are unsatisfactory for applications. Given this current state of development, achieving stable single-mode output over wide waveguide widths is a key development direction. Summary of the Invention

[0004] In order to achieve stable single-mode output on a wide waveguide layer, the present application provides a single-mode high-power edge-emitting laser and a preparation method thereof.

[0005] One of the objectives of this application is to provide a single-mode high-power edge-emitting laser, which adopts the following technical solution:

[0006] A single-mode high-power edge-emitting laser comprises a P-face structure layer, an active region, and an N-face structure layer. The upper surface of the P-face structure layer comprises a horizontal transverse length direction and a horizontal vertical width direction. A single-mode filter region for filtering laser light to form single-mode laser light is provided on the P-face structure layer. Single-mode enhancement regions for suppressing high-order laser modes are provided on both sides of the single-mode filter region in the horizontal transverse direction. The width of the single-mode enhancement region is greater than that of the single-mode filter region. High-order mode coupling regions for interfering with the propagation constant and coupling strength of high-order laser modes are provided on both sides of the single-mode enhancement region in the horizontal and vertical directions. The high-order mode coupling regions are passive structures. A single-mode amplification region for amplifying the single-mode power of the laser light is provided on a side of the single-mode enhancement region away from the single-mode filter region. The width of the single-mode amplification region is greater than that of the single-mode enhancement region.

[0007] By adopting the above technical solution, when the laser resonates, the laser generated in other areas will be mode filtered when passing through the single-mode filtering zone. The main function of the single-mode filtering zone is to generate and filter single modes. The high-order modes in the single-mode enhancement zone are confined to the lossy passive high-order mode coupling zone. The high-order modes will experience higher attenuation, thereby performing mode filtering or enhancing the loss of the high-order modes. The function of the high-order mode coupling zone is to use the passive high-order mode coupling structure to isolate specific modes, by interfering with the propagation constant and coupling strength of the high-order modes, but at the same time the fundamental mode is not affected, so that they can be distinguished and single-mode operation can be achieved. The single-mode amplification zone can increase the gain to amplify the single-mode power, which is equivalent to a single-mode power amplification structure. Because of the lateral size restrictions and mode filtering functions of the single-mode filtering zone and the single-mode enhancement zone, there is no need to worry about high-order mode lasing.

[0008] Preferably, a SiN protective layer is grown on the upper surface of the P-face structural layer, a strip-shaped opening is opened in the center of the protective layer, the axis of the opening coincides with the axis of the single-mode filtering area, and the two ends of the opening are respectively located above the opposite ends of the two single-mode amplification areas.

[0009] Preferably, the width of the single-mode filtering region in the horizontal and vertical directions is 3.5um, the width of the single-mode enhancement region in the horizontal and vertical directions is 6um, and the width of the high-order mode coupling region in the horizontal and vertical directions is not less than the width of the single-mode enhancement region in the horizontal and vertical directions.

[0010] By adopting the above technical solution, by controlling the lateral size to be small enough or by combining some small lateral size waveguides with single-mode amplifiers to optimize the waveguide structure, the single-mode output power can be improved while achieving single-mode.

[0011] Preferably, a tapered structural transition zone is provided between the single-mode amplification zone and the single-mode enhancement zone, and between the single-mode enhancement zone and the single-mode filtering zone.

[0012] By adopting the above technical solution, the structural transition zone plays a role of linking transition.

[0013] Preferably, the high-order mode coupling region includes an upper region and a lower region respectively located on both sides of the single-mode enhancement region, and the upper region and the lower region each have two channels.

[0014] Another object of the present application is to provide a method for preparing a single-mode high-power edge-emitting laser, using the following technical solution:

[0015] A method for preparing a single-mode high-power edge-emitting laser, used to prepare the above-mentioned single-mode high-power edge-emitting laser, comprises the following steps:

[0016] S1, etching the P-side cap layer to expose the P-side cladding layer, changing the area of ​​the P-side cap layer and the current injection efficiency;

[0017] S2. Perform secondary etching on the P-surface cap layer to form a ridge region and a high-order mode coupling region for interfering with the propagation constant and coupling strength of the high-order laser mode. Grooves are formed on both sides of the ridge region, and the bottom of the groove is located in the P-surface layer. A mesa structure is formed on the upper surface of the P-surface. The mesa structure includes a single-mode filter region located on the top of the ridge region for filtering the laser to form a single-mode laser. Single-mode enhancement regions are located on both sides of the single-mode filter region for suppressing the high-order laser mode. A single-mode amplification region is located on one side of the single-mode enhancement region away from the single-mode filter region for amplifying the single-mode power of the laser. The high-order mode coupling region is located on both sides of the width of the single-mode enhancement region in the horizontal direction.

[0018] S3. Covering the mesa structure with a layer of SiN, and then etching to open a SiN opening that passes through the single-mode filter region, the single-mode enhancement region, and the single-mode amplification region;

[0019] S4. Grow a P-side electrode on the SiN surface.

[0020] Preferably, the distance between the top of the ridge region and the bottom of the groove is 1.2 um.

[0021] Preferably, the high-order mode coupling region includes an upper region and a lower region, each of the upper region and the lower region has two layers, the width of the upper region in the horizontal and vertical directions is 4um, the distance between the two upper regions is 1um, the width of the lower region in the horizontal and vertical directions is 2.8um, and the spacing between the two lower regions is 1um.

[0022] Preferably, the horizontal and vertical widths of the openings in S3 are 2.5 μm.

[0023] In summary, this application has the following beneficial technical effects:

[0024] By using the single-mode enhancement zone, the high-order mode coupling zone to assist in generating the single mode and the combination of the single-mode amplification zone, the power can be further improved while ensuring the generation of the single mode. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a schematic top view of the p-side structural layer of an embodiment;

[0026] Figure 2 yes Figure 1 Schematic cross-sectional view in the AA direction.

[0027] Description of reference numerals:

[0028] 1. P-face structural layer; 2. Active area; 3. N-face structural layer; 4. Single-mode filtering area; 5. Single-mode enhancement area; 6. High-order mode coupling area; 7. Single-mode amplification area; 8. Opening; 9. Structural transition area; 10. Upper area; 11. Lower area; 12. P-face cap layer; 13. P-face cladding layer; 14. P-face waveguide layer; 15. Protective layer. DETAILED DESCRIPTION

[0029] The present application is further described in detail below in conjunction with all the accompanying drawings.

[0030] Example 1

[0031] The present application discloses a single-mode high-power edge-emitting laser. Figure 1 and Figure 2 , including a P-face structure layer 1, an active area 2 and an N-face structure layer 3. The P-face structure layer 1 includes a P-face cap layer 12, a P-face cladding layer 13 and a P-face waveguide layer 14 arranged in sequence from top to bottom.

[0032] Reference Figure 1 and Figure 2 A pattern is formed on the P-face cap layer 12 by photolithography and etching. The edges of the pattern are etched away to form a groove, and the lower end of the groove is located in the P-face cover layer 13. The top of the P-face structural layer 1 is square and is referred to as the top surface in this embodiment. The top surface shows a top view of the P-face structural layer 1. The top surface can show the specific structure of the pattern. The top surface is defined as the width direction in the horizontal vertical direction, and the top surface is defined as the length direction in the horizontal horizontal direction.

[0033] Reference Figure 1 and Figure 2 The pattern includes a single-mode filtering region 4, a single-mode enhancement region 5, a structural transition region 9, a high-order mode coupling region 6 and a single-mode amplification region 7.

[0034] Reference Figure 1 and Figure 2 The single-mode filter zone 4 is located in the middle of the top surface in a strip shape. The width of the single-mode filter zone 4 is 3.5 μm, and the length of the single-mode filter zone 4 is 800 μm. The single-mode enhancement zone 5 is coaxially arranged on both sides of the length direction of the single-mode filter zone 4. The width of the single-mode enhancement zone 5 is 6 μm, and the length of the single-mode enhancement zone 5 is 800 μm. The single-mode amplification zone 7 is coaxially arranged on the side of the single-mode enhancement zone 5 facing away from the single-mode filter zone 4. The width of the single-mode amplification zone 7 is 8 μm, and the length of the single-mode amplification zone 7 is 800 μm.

[0035] Reference Figure 1 and Figure 2 The structural transition region 9 is arranged in a trapezoidal shape and is located between the single-mode transition region and the single-mode enhancement region 5 and between the single-mode enhancement region 5 and the single-mode amplification region 7. The length of the structural transition region 9 is 200 μm.

[0036] Reference Figure 1 and Figure 2 The high-order mode coupling region 6 is in the shape of a long strip and is parallel to the single-mode enhancement region 5. The high-order mode coupling region 6 is located on both sides of the width direction of the single-mode enhancement region 5, and is respectively an upper region 10 and a lower region 11. The upper region 10 and the lower region 11 are each provided with two strips.

[0037] Reference Figure 1 and Figure 2 The width of the upper region 10 is 4 μm and the length is 800 μm. The spacing between the two upper regions 10 is 1 μm, and the spacing between the upper region 10 near the single-mode enhancement region 5 and the single-mode enhancement region 5 is 1 μm. The width of the lower region 11 is 2.8 μm and the length is 800 μm. The spacing between the two lower regions 11 is 1 μm, and the spacing between the lower region 11 near the single-mode enhancement region 5 and the single-mode enhancement region 5 is 1 μm.

[0038] Reference Figure 1 and Figure 2 A SiN protective layer 15 is grown on the entire top surface, and a strip-shaped opening 8 is opened in the center of the protective layer 15. The axis of the opening 8 coincides with the axis of the single-mode filter area 4, and the two ends of the opening 8 are respectively located above the opposite ends of the two single-mode amplification areas 7.

[0039] During laser resonance, the lasers generated in other areas will be subjected to mode filtering when passing through the single-mode filter zone 4. The main function of the single-mode filter zone 4 is to generate and filter single modes. The high-order modes in the single-mode enhancement zone 5 are confined to the lossy passive high-order mode coupling zone 6. The high-order modes will experience higher attenuation, thereby performing mode filtering or enhancing the loss of the high-order modes. The function of the high-order mode coupling zone 6 is to use the passive high-order mode coupling structure to isolate specific modes, and to distinguish them by interfering with the propagation constant and coupling strength of the high-order modes while leaving the fundamental mode unaffected, thereby achieving single-mode operation. The single-mode amplification zone 7 can increase the gain to amplify the single-mode power, which is equivalent to a single-mode power amplification structure. Because of the lateral size restrictions and mode filtering functions of the single-mode filter zone 4 and the single-mode enhancement zone 5, there is no need to worry about high-order mode lasing.

[0040] Example 2

[0041] The present application embodiment discloses a method for preparing a single-mode high-power edge-emitting laser, which is used to prepare a single-mode high-power edge-emitting laser in the above embodiment. Figure 1 and Figure 2 , including the following steps,

[0042] S1, etching the periphery of the P-side cap layer 12 to expose the P-side cover layer 13, changing the area of ​​the P-side cap layer 12 and the current injection efficiency;

[0043] S2. Perform a secondary etching on the P-side cap layer 12 to form a pattern. Grooves are formed on both sides of the pattern. The pattern includes a ridge region and a high-order mode coupling region 6. The bottom of the groove is located in the P-side cap layer 13. The distance between the top of the ridge region and the bottom of the groove is 1.2 μm.

[0044] A mesa structure with a pattern is formed on the upper surface of the P-plane structural layer 1 , and the mesa structure includes a single-mode filter area 4 located on the top of the ridge area.

[0045] The single-mode filter region 4 is flanked by single-mode enhancement regions 5 . The side of the single-mode enhancement region 5 away from the single-mode filter region 4 is a single-mode amplification region 7 . The high-order mode coupling region 6 is located on both sides of the width of the single-mode enhancement region 5 in the horizontal direction.

[0046] The single-mode filter zone 4 is located in the center of the top surface in a strip shape. Its width is 3.5 μm and its length is 800 μm. The single-mode enhancement zone 5 is coaxially arranged on either side of the length of the single-mode filter zone 4. The width of the single-mode enhancement zone 5 is 6 μm and its length is 800 μm. The single-mode amplification zone 7 is coaxially arranged on the side of the single-mode enhancement zone 5 facing away from the single-mode filter zone 4. The width of the single-mode amplification zone 7 is 8 μm and its length is 800 μm.

[0047] The structural transition region 9 is arranged in a trapezoidal shape and is located between the single-mode transition region and the single-mode enhancement region 5 and between the single-mode enhancement region 5 and the single-mode amplification region 7. The length of the structural transition region 9 is 200 μm.

[0048] The high-order mode coupling region 6 is in the shape of a long strip and is parallel to the single-mode enhancement region 5. The high-order mode coupling region 6 is located on both sides of the width direction of the single-mode enhancement region 5, and is respectively an upper region 10 and a lower region 11. The upper region 10 and the lower region 11 are each provided with two strips.

[0049] The width of the upper region 10 is 4 μm and the length is 800 μm. The spacing between two upper regions 10 is 1 μm, and the spacing between the upper region 10 near the single-mode enhancement region 5 and the single-mode enhancement region 5 is 1 μm. The width of the lower region 11 is 2.8 μm and the length is 800 μm. The spacing between two lower regions 11 is 1 μm, and the spacing between the lower region 11 near the single-mode enhancement region 5 and the single-mode enhancement region 5 is 1 μm.

[0050] S3. A 130 nm thick SiN layer is coated on the mesa structure to form a protective layer 15. Then, an opening 8 is formed by etching above the single-mode filter region 4, the single-mode enhancement region 5, and the single-mode amplifier region 7. The horizontal and vertical widths of opening 8 are 2.5 μm, and the length of opening 8 is 4800 μm. Opening 8 is located in the center of the mesa structure.

[0051] It should be noted that the high-order mode coupling region 6 is not open and no current will be injected subsequently, which means it is a passive structure.

[0052] S4. Grow a P-side electrode on the SiN surface.

[0053] The above are all preferred embodiments of the present application, and are not intended to limit the scope of protection of the present application. Therefore, any equivalent changes made based on the structure, shape, and principle of the present application should be included in the scope of protection of the present application.

Claims

1. A single-mode high-power edge-emitting laser, characterized in that: The invention comprises a P-face structural layer (1), an active region (2) and an N-face structural layer (3); the upper surface of the P-face structural layer (1) comprises a horizontal transverse length direction and a horizontal vertical width direction; a single-mode filtering region (4) for filtering laser light to form a single-mode laser light is provided on the P-face structural layer (1); the single-mode filtering region (4) is provided with a single-mode enhancement region (5) for suppressing laser high-order modes on both sides in the horizontal transverse direction; the width of the single-mode enhancement region (5) is greater than the width of the single-mode filtering region (4); the single-mode enhancement region (5) is provided with a high-order mode coupling region (6) for interfering with the propagation constant and coupling strength of the laser high-order mode on both sides in the horizontal and vertical directions; the high-order mode coupling region (6) is a passive structure; a single-mode amplification region (7) for amplifying the laser single-mode power is provided on a side of the single-mode enhancement region (5) away from the single-mode filtering region (4); the width of the single-mode amplification region (7) is greater than the width of the single-mode enhancement region (5).

2. The single-mode high-power edge-emitting laser according to claim 1, characterized in that: A SiN protective layer (15) is grown on the upper surface of the P-face structural layer (1), a strip-shaped opening (8) is provided at the center of the protective layer (15), the axis of the opening (8) coincides with the axis of the single-mode filtering area (4), and the two ends of the opening (8) are respectively located above the opposite ends of the two single-mode amplification areas (7).

3. The single-mode high-power edge-emitting laser according to claim 1, characterized in that: The width of the single-mode filtering region (4) in the horizontal and vertical directions is 3.5 μm, the width of the single-mode enhancement region (5) in the horizontal and vertical directions is 6 μm, and the width of the high-order mode coupling region (6) in the horizontal and vertical directions is not less than the width of the single-mode enhancement region (5) in the horizontal and vertical directions.

4. The single-mode high-power edge-emitting laser according to claim 3, characterized in that: A conical structural transition zone (9) is provided between the single-mode amplification zone (7) and the single-mode enhancement zone (5), and between the single-mode enhancement zone (5) and the single-mode filtering zone (4).

5. The single-mode high-power edge-emitting laser according to claim 1, characterized in that: The high-order mode coupling region (6) comprises an upper region (10) and a lower region (11) respectively located on both sides of the single-mode enhancement region (5), and each of the upper region (10) and the lower region (11) has two channels.

6. A method for preparing a single-mode high-power edge-emitting laser, characterized in that: The method for preparing a single-mode high-power edge-emitting laser according to any one of claims 1 to 5 comprises the following steps: S1, etching the P-side cap layer (12) to expose the P-side cover layer (13), and changing the area and current injection efficiency of the P-side cap layer (12); S2. Perform secondary etching on the P-surface cover layer (12) to form a ridge region and a high-order mode coupling region (6) for interfering with the propagation constant and coupling strength of the laser high-order mode. Grooves are formed on both sides of the ridge region, and the bottom of the groove is located in the P-surface layer (13). A table structure is formed on the upper surface of the P-surface. The table structure includes a single-mode filter region (4) located on the top of the ridge region for filtering the laser to form a single-mode laser. Both sides of the single-mode filter region (4) are single-mode enhancement regions (5) for suppressing the laser high-order mode. The side of the single-mode enhancement region (5) away from the single-mode filter region (4) is a single-mode amplification region (7) for amplifying the laser single-mode power. The high-order mode coupling region (6) is located on both sides of the width of the single-mode enhancement region (5) in the horizontal direction. S3, covering the mesa structure with a layer of SiN, and then etching to open a SiN opening (8) that runs through the single-mode filtering area (4), the single-mode enhancement area (5) and the single-mode amplification area (7); S4. Grow a P-side electrode on the SiN surface.

7. The method for preparing a single-mode high-power edge-emitting laser according to claim 6, wherein: The distance between the top of the ridge region and the bottom of the groove is 1.2 μm.

8. The method for preparing a single-mode high-power edge-emitting laser according to claim 6, wherein: The high-order mode coupling region (6) includes an upper region (10) and a lower region (11), each of the upper region (10) and the lower region (11) having two layers, the width of the upper region (10) in the horizontal and vertical directions is 4 μm, the distance between the two upper regions (10) is 1 μm, the width of the lower region (11) in the horizontal and vertical directions is 2.8 μm, and the distance between the two lower regions (11) is 1 μm.

9. The method for preparing a single-mode high-power edge-emitting laser according to claim 6, wherein: The width of the opening (8) in S3 in the horizontal and vertical directions is 2.5 μm.

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