A self-coherent broad ridge edge emitting semiconductor laser and its preparation method

Abstract

The invention discloses a self-coherent wide ridge edge emitting semiconductor laser and a preparation method, comprising: a semiconductor substrate; a semiconductor epitaxial layer is formed on the upper surface of the semiconductor substrate; a wide ridge waveguide region, a diffraction grating region, a self-coherent coupling region and a phase shift grating region are sequentially formed on the upper surface of the semiconductor epitaxial layer from one side to the other side; wherein the length of the self-coherent coupling region satisfies the Talbot distance; an insulating electrode window and a P metal electrode are sequentially formed on the upper surface of the wide ridge waveguide region from bottom to top, and an N metal electrode is formed on the lower surface of the semiconductor substrate; a high reflection film layer is formed on the end face of one side of the wide ridge waveguide region, and a semi-reflective and semi-transmissive film layer is formed on the end face of one side of the phase shift grating region. The invention realizes the output of the same phase mode, effectively improves the slow axis beam quality of the wide ridge edge emitting semiconductor laser under high power output, and the wide ridge edge emitting semiconductor laser with a single laser source is more stable during operation, and has the advantages of simple process and low cost.

Description

Technical Field

[0001] The invention relates to the technical field of semiconductor lasers, and in particular to a self-coherent broad ridge edge emitting semiconductor laser and a preparation method thereof. Background Art

[0002] Edge-emitting semiconductor lasers have the advantages of small size, high power, high efficiency, easy integration, high reliability, and easy modulation. Therefore, they have important applications in the fields of fiber coupling, solid-state laser pump sources, industrial processing, etc. High-power and high-beam quality lasers can achieve long-distance coherent detection and have obvious advantages in laser radar, laser communication, and optoelectronic countermeasures.

[0003] Edge-emitting laser arrays are an important way to obtain high-power and high-beam-quality lasers. To achieve laser array coherence, researchers have proposed several array methods, such as evanescent wave coupling and leaky wave coupling, all of which tend to operate in anti-phase mode, affecting the breadth of their applications.

[0004] In order to obtain the same-phase mode laser output, it is necessary to reduce the competitiveness of other high-order supermodes by introducing additional losses; and the laser array of multiple light sources is not ideal in terms of device design, experimental process, cost, and ensuring the simultaneous and stable operation of multiple light sources during subsequent testing. Summary of the invention

[0005] In view of the deficiencies in the prior art, the present invention provides a self-coherent wide-ridge edge emitting semiconductor laser and a preparation method thereof. The laser effectively avoids the loss caused by mode competition during operation, realizes in-phase mode output, and the far-field light field energy is more concentrated at a central point, which is conducive to high-power and high-beam quality output of the device. In addition, the manufacture of a single wide light source is more friendly to the process, cost and stability of device operation.

[0006] The present invention discloses a self-coherent wide ridge edge emitting semiconductor laser, comprising: a semiconductor substrate;

[0007] A semiconductor epitaxial layer is formed on the upper surface of the semiconductor substrate;

[0008] A wide ridge waveguide region, a diffraction grating region, a self-coherent coupling region and a phase shift grating region are sequentially formed on the upper surface of the semiconductor epitaxial layer from one side to the other side; wherein the length of the self-coherent coupling region satisfies the Talbot distance;

[0009] An insulating electrode window and a P metal electrode are sequentially formed on the upper surface of the wide ridge waveguide region from bottom to top, and an N metal electrode is formed on the lower surface of the semiconductor substrate;

[0010] A high reflection film layer is formed on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the wide ridge waveguide region, and a semi-reflective and semi-transmissive film layer is formed on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the phase-shift grating region.

[0011] As a further improvement of the present invention, the cross-section of the wide ridge waveguide region is rectangular, the length of the wide ridge waveguide region is 2 mm to 5 mm, the width is 100 μm to 500 μm, and the height is 1 μm to 1.5 μm.

[0012] As a further improvement of the present invention, the diffraction grating area is formed by a periodic air groove array, the air groove length is 3μm to 5μm, the width is 5μm to 10μm, the depth is 1.5μm to 2μm, the period is 10μm to 20μm, and the number of the array is 5 to 50.

[0013] As a further improvement of the present invention, the self-coherent coupling region has no electrical injection, the width of the self-coherent coupling region is equal to the width of the wide ridge waveguide region, and the length Z t for:

[0014] Z t =2nd 2 / λ

[0015] In the formula, n is the material equivalent refractive index of the semiconductor epitaxial layer in the region where the self-coherent coupling region is located, d is the array period of the air grooves in the diffraction grating region, and λ is the wavelength of free space light.

[0016] As a further improvement of the present invention, the phase shift grating region is formed by a periodic medium groove array, which is symmetrically distributed on both sides of the self-coherent coupling region with the diffraction grating region, and the medium groove width is 5μm to 10μm, the depth is 1.5μm to 2μm, the period is 10μm to 20μm, the number of arrays is: 5 to 50, and the length satisfies the formula:

[0017] L=Δφ·λ / 2π·Δn, where Δφ is the phase difference of the supermode light field at different positions inside the phase-shift grating region, λ is the wavelength of free-space light, and Δn is the equivalent refractive index difference between the material of the semiconductor epitaxial layer in the area where the self-coherent coupling region is located and the dielectric material in the dielectric groove.

[0018] As a further improvement of the present invention, the insulating electrode window is formed of one of silicon nitride or silicon oxide, distributed at the center of the upper surface of the wide ridge waveguide region, and the insulating electrode window has a length of 1.9 mm to 4.9 mm, a width of 90 μm to 490 μm, and a height of 200 nm to 500 nm.

[0019] As a further improvement of the present invention, the semiconductor substrate is selected from: gallium arsenide, indium phosphide or gallium nitride.

[0020] As a further improvement of the present invention, the semiconductor epitaxial layers are, from bottom to top, N-type doped limiting layer, N-type doped waveguide layer, undoped active layer, P-type doped waveguide layer, P-type doped limiting layer, and highly doped ohmic contact layer; wherein the thickness of the P-type doped waveguide layer is less than the thickness of the N-type doped waveguide layer.

[0021] As a further improvement of the present invention, the P metal electrode includes one or more of titanium, gold and platinum; the N metal electrode includes one or more of gold, germanium and palladium.

[0022] As a further improvement of the present invention, the high reflective film layer is an alternately grown SiO 2 Layer and Ta 2 O 5 The semi-reflective and semi-transparent film layers are alternately grown SiO 2 Layer and Ta 2 O 5 Layers, each layer is 50nm to 150nm thick and has a reflectivity of 48-52%.

[0023] The present invention also discloses a method for preparing a self-coherent broad ridge edge emitting semiconductor laser, comprising:

[0024] selecting a semiconductor substrate;

[0025] Growing a semiconductor epitaxial layer on the surface of a semiconductor substrate;

[0026] Etching a wide ridge waveguide region on the upper surface of the semiconductor epitaxial layer;

[0027] A diffraction grating region is etched on one side of the wide ridge waveguide region on the upper surface of the semiconductor epitaxial layer;

[0028] On the upper surface of the semiconductor epitaxial layer, a phase shift grating region is etched at a preset length on the other side of the diffraction grating region and filled with dielectric material, so that a self-coherent coupling region is formed between the diffraction grating region and the phase shift grating region;

[0029] Depositing and etching a dielectric material on the upper surface of the wide ridge waveguide region to form an insulating electrode window;

[0030] Sputtering a P metal electrode on the upper surface of the insulating electrode window;

[0031] sputtering an N metal electrode on the lower surface of the semiconductor substrate;

[0032] Vapor-depositing a high-reflective film layer on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the wide ridge waveguide region;

[0033] A semi-reflective and semi-transmissive film layer is evaporated on the end surface of the semiconductor substrate and the semiconductor epitaxial layer at one side of the phase-shift grating region.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention sequentially arranges four functional areas, namely, a wide ridge waveguide area, a diffraction grating area, a self-coherent coupling area, and a phase shift grating area, on the upper surface of the semiconductor epitaxial layer. The wide ridge waveguide area provides a high-power light source, the diffraction grating area splits a beam of light into multiple sub-light sources with the same wavelength, the self-coherent coupling area utilizes the Talbot effect to coherently couple multiple sub-light sources with the same wavelength, and the phase shift grating area compensates for the non-zero phase light field in the supermode light field, and finally realizes the zero-phase in-phase mode light field output. The present invention effectively avoids the loss caused by supermode competition in the multi-laser unit array structure, and avoids the instability of the operation of the multi-laser units; it not only has a simple process and low cost, but also provides a new type of high-power, high-beam quality device innovation idea. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a front view of the self-coherent broad ridge edge emitting semiconductor laser disclosed in the present invention;

[0037] Figure 2 A top view of the self-coherent broad ridge edge emitting semiconductor laser disclosed in the present invention;

[0038] Figure 3 It is a schematic diagram of the back cavity surface structure of the self-coherent wide ridge edge emitting semiconductor laser disclosed in the present invention;

[0039] Figure 4 The present invention is a schematic diagram of the front cavity surface structure of the self-coherent wide ridge edge emitting semiconductor laser disclosed in the present invention.

[0040] In the figure:

[0041] 1. N metal electrode; 2. Semiconductor substrate; 3. N-type doped confinement layer; 4. N-type doped waveguide layer; 5. Undoped active layer; 6. P-type doped waveguide layer; 7. P-type doped confinement layer; 8. Highly doped ohmic contact layer; 9. Insulated electrode window; 10. P metal electrode; 11. Highly reflective film layer; 12. Diffraction grating area; 13. Phase-shift grating area; 14. Semi-reflective and semi-transparent film layer; 15. Wide ridge waveguide area; 16. Self-coherent coupling area. DETAILED DESCRIPTION

[0042] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The present invention is further described in detail below in conjunction with the accompanying drawings:

[0044] like Figures 1 to 4 As shown, the present invention provides a self-coherent wide ridge edge emitting semiconductor laser, comprising: a semiconductor substrate 2 and a semiconductor epitaxial layer formed on the upper surface of the semiconductor substrate 2; wherein,

[0045] The semiconductor epitaxial layers grow sequentially from bottom to top, including an N-type doped confinement layer 3, an N-type doped waveguide layer 4, an undoped active layer 5, a P-type doped waveguide layer 6, a P-type doped confinement layer 7 and a highly doped ohmic contact layer 8 grown on the upper surface of a semiconductor substrate 2, wherein the thickness of the P-type doped waveguide layer 6 is less than the thickness of the N-type doped waveguide layer 4; preferably, the semiconductor substrate 2 is a GaAs substrate, the N-type doped confinement layer 3 is an N-type doped AlGaAs confinement layer, the N-type doped waveguide layer 4 is an N-type doped AlGaAs waveguide layer, the undoped active layer 5 is an InGaAs / GaAsP single quantum well / barrier active layer, the P-type doped waveguide layer 6 is a P-type doped AlGaAs waveguide layer, the P-type doped confinement layer 7 is a P-type doped AlGaAs confinement layer, and the highly doped ohmic contact layer 8 is a highly doped GaAs ohmic contact layer.

[0046] The present invention sequentially arranges (from left to right) a wide ridge waveguide region 15, a diffraction grating region 12, a self-coherent coupling region 16 and a phase shift grating region 13 on the upper surface of the semiconductor epitaxial layer; specifically:

[0047] The wide ridge waveguide region 15 of the present invention has a rectangular cross section, a length of 2 mm to 5 mm, a width of 100 μm to 500 μm, and a height of 1 μm to 1.5 μm.

[0048] The diffraction grating area 12 of the present invention is formed by a periodic air groove array, wherein a single air groove has a length of 3 μm to 5 μm, a width of 5 μm to 10 μm, a depth of 1.5 μm to 2 μm, a period of 10 μm to 20 μm, and an array number of 5 to 50.

[0049] The self-coherent coupling region 16 of the present invention has no electrical injection, the width of the self-coherent coupling region 16 is equal to the width of the wide ridge waveguide region, and the length Z t for:

[0050] Z t =2nd 2 / λ

[0051] Wherein, n is the material equivalent refractive index of the semiconductor epitaxial layer in the region where the self-coherent coupling region 16 is located, d is the array period of the air grooves in the diffraction grating region 12, and λ is the wavelength of the free space light.

[0052] The phase shift grating area 13 of the present invention is formed by a periodic medium groove array, which is symmetrically distributed with the diffraction grating area 12 on both sides of the self-coherent coupling area 16. The medium groove width is 5μm to 10μm, the depth is 1.5μm to 2μm, the period is 10μm to 20μm, the number of arrays is 5 to 50, and the length satisfies the formula:

[0053] L=Δφ·λ / 2π·Δn, where Δφ is the phase difference of the supermode light field at different positions inside the phase-shift grating region 13, λ is the wavelength of the free-space light, and Δn is the equivalent refractive index difference between the material of the semiconductor epitaxial layer in the self-coherent coupling region 16 and the dielectric material in the dielectric groove.

[0054] The present invention sequentially arranges an insulating electrode window 9 and a P metal electrode 10 on the upper surface of a wide ridge waveguide region 15 from bottom to top, and arranges an N metal electrode 1 on the lower surface of a semiconductor substrate 2; wherein the insulating electrode window 9 is formed of one of silicon nitride or silicon oxide, and is distributed at the center of the upper surface of the wide ridge waveguide region 15, and the insulating electrode window 9 has a length of 1.9 mm to 4.9 mm, a width of 90 μm to 490 μm, and a height of 200 nm to 500 nm; the P metal electrode 10 includes one or more of titanium, gold and platinum; and the N metal electrode 1 includes one or more of gold, germanium and palladium.

[0055] The present invention provides a high-reflection film layer 11 on the other side (left side) of the wide ridge waveguide region 15, and a semi-reflective and semi-transmissive film layer 14 on the other side of the phase-shift grating region 13; wherein the high-reflection film layer 11 is an alternately grown SiO 2 Layer and Ta 2 O 5 The thickness of each layer is 50nm to 150nm, and the reflectivity is 96% to 100%; the semi-reflective and semi-transparent film layer is an alternately grown SiO 2 Layer and Ta 2 O 5 Layers, each layer is 50nm to 150nm thick and has a reflectivity of 48-52%.

[0056] The present invention provides a method for preparing the self-coherent broad ridge edge emitting semiconductor laser, comprising:

[0057] Step 1, selecting a semiconductor substrate 2;

[0058] Step 2, sequentially growing an N-type doped confinement layer 3, an N-type doped waveguide layer 4, an undoped active layer 5, a P-type doped waveguide layer 6, a P-type doped confinement layer 7 and a highly doped ohmic contact layer 8 on the upper surface of the semiconductor substrate 2 to form a semiconductor epitaxial layer;

[0059] Step 3, etching the upper surface of the semiconductor epitaxial layer to form a wide ridge waveguide region 15;

[0060] Step 4: On the upper surface of the semiconductor epitaxial layer, a diffraction grating region 12 is etched on one side of the wide ridge waveguide region 15; and one side of the wide ridge waveguide region 15 is etched and filled to form a phase shift grating region 13;

[0061] Step 5: On the upper surface of the semiconductor epitaxial layer, the other side Z of the diffraction grating area 12 t The phase shift grating region 13 is formed by etching and filling at the length, and a self-coherent coupling region 16 is formed between the diffraction grating region 12 and the phase shift grating region 13;

[0062] Step 6: depositing and etching dielectric material on the upper surface of the wide ridge waveguide region 15 to form an insulating electrode window 9;

[0063] Step 7, sputtering a P metal electrode 10 on the upper surface of the insulating electrode window 9;

[0064] Step 8, sputtering an N metal electrode 1 on the lower surface of the semiconductor substrate 2;

[0065] Step 9, evaporating a high reflective film layer 11 on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the wide ridge waveguide region 15;

[0066] Step 10: evaporate a semi-reflective and semi-transmissive film layer 14 on the end surface of the semiconductor substrate and the semiconductor epitaxial layer at one side of the phase-shift grating region.

[0067] Example:

[0068] Taking a gallium arsenide semiconductor laser with an operating wavelength of 980nm as an example, its preparation method includes:

[0069] S1. Select a gallium arsenide substrate as the semiconductor substrate 2.

[0070] S2. On a GaAs substrate, an N-type doped confinement layer 3, an N-type doped waveguide layer 4, an undoped active layer 5, a P-type doped waveguide layer 6, a P-type doped confinement layer 7, and a highly doped ohmic contact layer 8 are grown in sequence from bottom to top by using a metal organic compound vapor deposition method (MOCVD) or a molecular beam epitaxy method (MBE) to form a semiconductor epitaxial layer; wherein the N-type doped confinement layer 3 is an N-type doped Al 0.30 GaAs confinement layer, doping concentration is 3e 18 cm -3 , with a thickness of 1.5μm to 2μm; the N-type doped waveguide layer 4 is N-type doped Al 0.20 GaAs waveguide layer, doping concentration is 1.5e 17 cm -3 , with a thickness of 1 μm to 1.2 μm; the undoped active layer 5 adopts a single quantum well structure, in which the quantum well is In 0.16 GaAs material, thickness is 0.008μm~0.01μm, quantum barrier is Ga 0.16AsP material, thickness is 0.008μm~0.020μm; P-type doped waveguide layer 6 is P-type doped Al 0.20 GaAs waveguide layer, doping concentration is 1.5e 17 cm -3 , with a thickness of 0.8μm to 1μm; the P-type doped limiting layer 7 is a P-type doped Al 0.35 GaAs confinement layer, doping concentration is 3e 18 cm -3 , with a thickness of 1 μm to 1.2 μm; in order to reduce the series resistance of the device, a highly doped ohmic contact layer 8 is grown on the P-type doped limiting layer 7, and the highly doped ohmic contact layer 8 is a highly doped GaAs ohmic contact layer with a concentration of 1e 20 cm -3 , thickness is 0.2μm~0.3μm.

[0071] S3. Use a spinning machine to evenly coat positive photoresist, and adopt an ultraviolet photolithography machine exposure method. After development, a wide ridge waveguide region 15 photoresist pattern is obtained on the upper surface of the highly doped ohmic contact layer 8, and then an inductively coupled plasma method is used to etch the wide ridge waveguide region 15; wherein, the cross-section of the wide ridge waveguide region 15 is rectangular, with a length of 2mm to 5mm, a width of 100μm to 500μm, and a height of 1μm to 1.5μm.

[0072] S4, cleaning the semiconductor epitaxial wafer with acetone, ethanol and deionized water for many times, drying the moisture on the upper surface, lower surface and surrounding surface of the semiconductor epitaxial wafer with a nitrogen gun, cleaning the semiconductor epitaxial wafer again with a glue sprayer, applying positive photoresist with a glue spinner, exposing with a UV lithography machine, and developing the photoresist pattern of the phase shift grating region 13 on the upper surface of the highly doped ohmic contact layer 8, etching with an inductively coupled plasma method to obtain an air groove in the phase shift grating region 13, and then filling the optical medium material with a plasma chemical vapor deposition method to form a medium groove, such as SiO 2 、Si 3 N 4 The width of the medium groove is 5 μm to 10 μm, the depth is 1.5 μm to 2 μm, the period is 10 μm to 20 μm, the number of arrays is 5 to 50, and the length is calculated by the formula L=Δφ / Δn according to actual needs.

[0073] S5, using a spinning machine to evenly coat the positive photoresist, using an ultraviolet photolithography machine for exposure, and then using an inductively coupled plasma method to etch the remaining dielectric materials outside the phase-shift grating area 13.

[0074] S6, a spinning machine is used to uniformly coat positive photoresist, and an ultraviolet photolithography machine is used for exposure. After development, a photoresist pattern of a diffraction grating area 12 is obtained on the upper surface of the highly doped ohmic contact layer 8, and an air groove of the diffraction grating area 12 is obtained by etching using an inductively coupled plasma method. The air groove has a length of 3μm to 5μm, a width of 5μm to 10μm, a depth of 1.5μm to 2μm, a period of 10μm to 20μm, and an array number of 5 to 50. A self-coherent coupling area 16 is formed between the diffraction grating area 12 and the phase shift grating area 13, and the length is given by the formula Z t =2nd 2 / λ is calculated according to actual needs.

[0075] S7, using plasma chemical vapor deposition to deposit dielectric materials, such as SiO 2 、Si 3 N 4 The positive photoresist is evenly coated on a spinning machine, and an ultraviolet photolithography machine is used for exposure. After development, an insulating electrode window 9 photoresist pattern is obtained on the upper surface of the wide ridge waveguide region 15. The insulating electrode window 9 is etched by an inductively coupled plasma method, and has a length of 1.9 mm to 4.9 mm, a width of 90 μm to 490 μm, and a height of 200 nm to 500 nm.

[0076] S8. Use magnetron sputtering to sputter the P metal electrode 10 on the top of the insulating electrode window 9, and sputter in sequence: titanium metal is 40nm~50nm, platinum metal is 40nm~50nm, and gold metal is 300nm~400nm.

[0077] S9. Thinning and polishing the lower surface of the gallium arsenide substrate, and the remaining substrate thickness is 100 μm to 120 μm.

[0078] S10, sputtering an N metal electrode 1 on the lower surface of the gallium arsenide substrate by a magnetron sputtering method, and sputtering in sequence: nickel metal 20nm-30nm, gold-germanium alloy metal 90nm-100nm, and gold metal 300nm-400nm.

[0079] S11, performing alloy annealing treatment on the semiconductor epitaxial wafer using an alloy annealing machine.

[0080] S12, using a cleaving machine to cleave the array bars.

[0081] S13, using the electron beam evaporation method, evaporating the high reflection film layer 11 on the other end face (back cavity face) of the wide ridge waveguide area 15, and evaporating the semi-reflective and semi-transmissive film layer 14 on the other end face (front cavity face) of the phase shift grating area 13; alternately depositing different logarithms of SiO 2 / Ta 2 O 5The optical medium film makes the reflectivity of the front cavity surface reach 48% to 52%, and the reflectivity of the back cavity surface reach 96% to 100%.

[0082] S12. Cleavage the single tube using a cleavage machine.

[0083] S13. Use P-side down flip-chip bonding to package the single tube on a COS heat sink with gold-tin solder, and perform device performance testing.

[0084] The advantages of the present invention are:

[0085] The present invention sequentially arranges four functional areas, namely, a wide ridge waveguide area, a diffraction grating area, a self-coherent coupling area, and a phase shift grating area, on the upper surface of the semiconductor epitaxial layer. The wide ridge waveguide area provides a high-power light source. The diffraction grating area splits a beam of high-power light provided by the wide ridge waveguide area into multiple sub-light sources with the same wavelength. These sub-light sources achieve coherent coupling in the self-coherent coupling area with a length of Talbot distance to form a supermode light field. The phase shift grating area compensates for the non-zero phase light field in the supermode light field, and finally achieves zero-phase in-phase mode light field output. This method effectively avoids the loss caused by supermode competition in the multi-laser unit array structure, and avoids the instability of the operation of the multi-laser unit; the present invention not only has a simple process and low cost, but also provides a new type of high-power, high-beam quality device innovation idea.

[0086] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A self-coherent broad ridge edge emitting semiconductor laser, characterized in that: include: Semiconductor substrate; A semiconductor epitaxial layer is formed on the upper surface of the semiconductor substrate; A wide ridge waveguide region, a diffraction grating region, a self-coherent coupling region and a phase shift grating region are sequentially formed on the upper surface of the semiconductor epitaxial layer from one side to the other side; wherein the length of the self-coherent coupling region satisfies the Talbot distance; An insulating electrode window and a P metal electrode are sequentially formed on the upper surface of the wide ridge waveguide region from bottom to top, and an N metal electrode is formed on the lower surface of the semiconductor substrate; A high reflection film layer is formed on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the wide ridge waveguide region, and a semi-reflective and semi-transmissive film layer is formed on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the phase-shift grating region.

2. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The semiconductor substrate is selected from: gallium arsenide, indium phosphide or gallium nitride; The semiconductor epitaxial layers are, from bottom to top, N-type doped limiting layer, N-type doped waveguide layer, undoped active layer, P-type doped waveguide layer, P-type doped limiting layer, and highly doped ohmic contact layer; wherein the thickness of the P-type doped waveguide layer is less than the thickness of the N-type doped waveguide layer.

3. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The cross section of the wide ridge waveguide region is rectangular, the length of the wide ridge waveguide region is 2 mm to 5 mm, the width is 100 μm to 500 μm, and the height is 1 μm to 1.5 μm.

4. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The diffraction grating area is formed by a periodic air groove array, the air groove length is 3μm to 5μm, the width is 5μm to 10μm, the depth is 1.5μm to 2μm, the period is 10μm to 20μm, and the number of the array is 5 to 50.

5. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The self-coherent coupling region has no electrical injection, the width of the self-coherent coupling region is equal to the width of the wide ridge waveguide region, and the length Z t for: Z t =2nd 2 / λ In the formula, n is the material equivalent refractive index of the semiconductor epitaxial layer in the region where the self-coherent coupling region is located, d is the array period of the air grooves in the diffraction grating region, and λ is the wavelength of free space light.

6. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The phase shift grating area is formed by a periodic medium groove array, which is symmetrically distributed on both sides of the self-coherent coupling area with the diffraction grating area. The medium groove has a width of 5 μm to 10 μm, a depth of 1.5 μm to 2 μm, a period of 10 μm to 20 μm, an array number of 5 to 50, and a length that satisfies the formula: L=Δφ·λ / 2π·Δn Wherein, Δφ is the phase difference of the supermode light field at different positions inside the phase-shift grating region, λ is the wavelength of free-space light, and Δn is the equivalent refractive index difference between the material of the semiconductor epitaxial layer in the region where the self-coherent coupling region is located and the dielectric material in the dielectric groove.

7. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The insulating electrode window is formed of silicon nitride or silicon oxide, and is distributed at the center of the upper surface of the wide ridge waveguide region. The insulating electrode window has a length of 1.9 mm to 4.9 mm, a width of 90 μm to 490 μm, and a height of 200 nm to 500 nm.

8. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The P metal electrode includes one or more of titanium, gold and platinum; the N metal electrode includes one or more of gold, germanium and palladium.

9. The self-coherent broad ridge edge emitting semiconductor laser according to claim 1, characterized in that: The high-reflective film layer is an alternately grown SiO2 layer and a Ta2O5 layer, each layer is 50nm to 150nm thick, and the reflectivity is 96% to 100%; the semi-reflective and semi-transparent film layer is an alternately grown SiO2 layer and a Ta2O5 layer, each layer is 50nm to 150nm thick, and the reflectivity is 48-52%.

10. A method for preparing a self-coherent broad ridge edge emitting semiconductor laser according to any one of claims 1 to 9, characterized in that: include: selecting a semiconductor substrate; Growing a semiconductor epitaxial layer on the surface of a semiconductor substrate; Etching a wide ridge waveguide region on the upper surface of the semiconductor epitaxial layer; A diffraction grating region is etched on one side of the wide ridge waveguide region on the upper surface of the semiconductor epitaxial layer; On the upper surface of the semiconductor epitaxial layer, a phase shift grating region is etched at a preset length on the other side of the diffraction grating region and filled with dielectric material, so that a self-coherent coupling region is formed between the diffraction grating region and the phase shift grating region; Depositing and etching a dielectric material on the upper surface of the wide ridge waveguide region to form an insulating electrode window; Sputtering a P metal electrode on the upper surface of the insulating electrode window; sputtering an N metal electrode on the lower surface of the semiconductor substrate; Vapor-depositing a high-reflective film layer on the end surface of the semiconductor substrate and the semiconductor epitaxial layer on one side of the wide ridge waveguide region; A semi-reflective and semi-transmissive film layer is evaporated on the end surface of the semiconductor substrate and the semiconductor epitaxial layer at one side of the phase-shift grating region.

Images