A long-wavelength vertical cavity surface emitting semiconductor laser and its preparation method

Abstract

The present invention discloses a long-wavelength vertical cavity surface emitting semiconductor laser, which includes a DBR reflector, a lower current injection layer, a light-emitting area, an upper current injection layer and a reflection grating from bottom to top, wherein the DBR reflector and the reflection grating are arranged relative to each other, and the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector. At this time, the light generated by the light-emitting area located between the reflection grating and the DBR reflector will oscillate between the reflection grating and the DBR reflector to generate laser, and the light will be emitted from the reflection grating to the semiconductor laser, and the position of the above-mentioned reflection grating is the position of the light-emitting hole in the semiconductor laser. Since the structure of the reflection grating is simple and the preparation process is simple, the preparation cost of the laser can be reduced. The present invention also provides a preparation method, which also has the above-mentioned beneficial effects.

Description

Technical Field

[0001] The present invention relates to the technical field of semiconductor lasers, and in particular to a long-wavelength vertical cavity surface emitting semiconductor laser and a method for preparing the long-wavelength vertical cavity surface emitting semiconductor laser. Background Art

[0002] Vertical Cavity Surface Emitting Semiconductor Laser, or VCSEL laser, is a semiconductor laser that emits light vertically from the surface. It has the advantages of low threshold, small divergence angle, high laser power density, easy monolithic integration, good thermal stability, etc. It has extremely important applications in medical treatment, sensing, display technology, information storage, space communication and satellite navigation. Since long-wavelength VCSEL lasers have very broad prospects in high-end applications such as long-distance communication, gas sensing, and lidar, how to improve the preparation efficiency of long-wavelength VCSEL lasers and reduce the difficulty of preparation has been a hot topic in recent years.

[0003] Long-wavelength VCSEL lasers are usually made of InP-based materials. Such materials cannot be prepared using the side oxidation process commonly used in near-infrared band VCSELs to prepare light-emitting holes. The current common method is to prepare a tunnel junction conductive layer with an extremely high doping concentration near the light-emitting area, and first etch the tunnel junction conductive layer by etching, retain a portion of the tunnel junction conductive layer, and then continue to grow the light-emitting area material layer on it. After the light-emitting area material layer is grown, an optical reflector composed of multiple layers of thin films is prepared above the light-emitting area. In this way, the position of the light-emitting hole in the light-emitting area is determined by the position of the highly doped tunnel junction conductive layer. Therefore, this process involves two very difficult preparation processes: the material preparation process with ultra-high doping concentration and the secondary epitaxial process of the light-emitting area. High doping can easily cause internal defects in the material, affecting reliability, and the doped atoms have a strong absorption effect on light. The position of the highly doped tunnel junction material layer must be precisely controlled at the standing wave node position of the oscillating light. A position deviation of several nanometers will cause a significant increase in the absorption coefficient of the laser, causing its light-emitting performance to decay sharply. Therefore, the current long-wavelength VCSEL laser is limited by the above-mentioned preparation process, and the development is very difficult and the manufacturing cost is extremely high. There is an urgent need for a simple and practical method to solve the problem of preparing the light output hole of the long-wavelength VCSEL laser. Summary of the invention

[0004] The object of the present invention is to provide a long-wavelength vertical cavity surface emitting semiconductor laser, which can simply prepare a long-wavelength VCSEL laser; another object of the present invention is to provide a method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser, which can simply prepare a long-wavelength VCSEL laser.

[0005] In order to solve the above technical problems, the present invention provides a long-wavelength vertical cavity surface emitting semiconductor laser, comprising:

[0006] DBR reflector;

[0007] A lower current injection layer located on the surface of the DBR reflector;

[0008] A light emitting area located on a surface of the lower current injection layer facing away from the DBR reflector;

[0009] An upper current injection layer located on a surface of the light emitting area facing away from the DBR reflector;

[0010] A reflection grating with a preset light-emitting area on the surface of the upper current injection layer facing away from the DBR reflector; the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector.

[0011] Optionally, the reflectivity of the reflection grating ranges from 95% to 99%, including endpoint values.

[0012] Optionally, a surface of the lower current injection layer facing away from the DBR reflector has a stepped surface, and a lower electrode is provided on the stepped surface; and an upper electrode is provided on a surface of the upper current injection layer facing away from the DBR reflector.

[0013] Optionally, the light-emitting region is a quantum well light-emitting region or a quantum dot light-emitting region.

[0014] Optionally, at least two light-emitting areas are provided on the surface of the lower current injection layer facing away from the DBR reflector, and adjacent light-emitting areas are isolated from each other; a corresponding upper current injection layer is provided on the surface of any light-emitting area facing away from the DBR reflector; and a corresponding reflection grating is provided on the light-emitting area of ​​any upper current injection layer facing away from the DBR reflector.

[0015] Optionally, at least two mutually isolated reflection gratings are provided on the surface of the upper current injection layer facing away from the DBR reflector, and the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the upper current injection layer; the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the lower current injection layer.

[0016] The present invention also provides a method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser, comprising:

[0017] Growing the DBR reflector by an epitaxial growth process;

[0018] epitaxially growing a lower current injection layer on the surface of the DBR reflector;

[0019] Epitaxially growing a light-emitting region on the surface of the lower current injection layer facing away from the DBR reflector;

[0020] Epitaxially growing an upper current injection layer on the surface of the light emitting region facing away from the DBR reflector;

[0021] Epitaxially growing a grating layer on the surface of the upper current injection layer region facing away from the DBR reflector;

[0022] Etching the grating layer to remove the grating layer in the non-light emitting area on the surface of the upper current injection layer facing away from the DBR reflector;

[0023] The grating layer in the light emitting area on the surface of the upper current injection layer facing away from the DBR reflector is etched into a reflection grating to produce the long-wavelength vertical cavity surface emitting semiconductor laser; the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector.

[0024] Optionally, after epitaxially growing a grating layer on a surface of the upper current injection layer region facing away from the DBR reflector, the method further comprises:

[0025] The grating layer, the upper current injection layer and the light-emitting region are sequentially etched from the surface of the grating layer on the side facing away from the DBR reflector to form a step surface on the surface of the lower current injection layer on the side facing away from the DBR reflector;

[0026] Disposing a lower electrode on the surface of the step surface;

[0027] After etching the grating layer, the method further comprises:

[0028] An upper electrode is arranged in a non-light emitting area on a surface of the upper current injection layer facing away from the DBR reflector.

[0029] A long-wavelength vertical cavity surface emitting semiconductor laser provided by the present invention includes, from bottom to top, a DBR reflector, a lower current injection layer, a light-emitting area, an upper current injection layer and a reflection grating, wherein the DBR reflector and the reflection grating are arranged relative to each other, and the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector. At this time, the light generated by the light-emitting area located between the reflection grating and the DBR reflector will oscillate between the reflection grating and the DBR reflector to generate laser, and because the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector, the light will be emitted from the reflection grating to the semiconductor laser, and the position of the above-mentioned reflection grating is the position of the light-emitting hole in the semiconductor laser. Since the reflection grating has a simple structure and a simple preparation process, the preparation of the light-emitting hole of the long-wavelength VCSEL laser can be greatly simplified, thereby reducing the preparation cost of the long-wavelength VCSEL laser.

[0030] The present invention also provides a method for preparing a long-wavelength vertical-cavity surface-emitting semiconductor laser. The prepared long-wavelength vertical-cavity surface-emitting semiconductor laser also has the above-mentioned beneficial effects, which will not be described in detail here. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions of the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0032] Figure 1 A schematic diagram of the structure of a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by an embodiment of the present invention;

[0033] Figure 2 A schematic structural diagram of a specific long-wavelength vertical-cavity surface-emitting semiconductor laser provided by an embodiment of the present invention;

[0034] Figure 3 A schematic structural diagram of another specific long-wavelength vertical-cavity surface-emitting semiconductor laser provided by an embodiment of the present invention;

[0035] Figure 4 A flow chart of a method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser provided by an embodiment of the present invention;

[0036] Figure 5 The present invention provides a flowchart of a specific method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser.

[0037] In the figure: 1. DBR reflector, 2. lower current injection layer, 3. light emitting area, 4. upper current injection layer, 5. reflection grating, 6. lower electrode, 7. upper electrode. DETAILED DESCRIPTION

[0038] The core of the present invention is to provide a long-wavelength vertical cavity surface emitting semiconductor laser. In the prior art, long-wavelength VCSEL lasers are usually composed of InP-based materials. Such materials cannot use the side oxidation process commonly used in near-infrared band VCSELs to prepare light-emitting holes. The current common method is to prepare a tunnel junction conductive layer with an extremely high doping concentration near the light-emitting area, and first etch the tunnel junction conductive layer by an etching method, retain a portion of the tunnel junction conductive layer, and then continue to grow the light-emitting area material layer above it. After the light-emitting area material layer is grown, an optical reflector composed of multiple layers of thin films is prepared above the light-emitting area. In this way, the position of the light-emitting hole in the light-emitting area is determined by the position of the highly doped tunnel junction conductive layer. Therefore, the process involves two very difficult preparation processes: the material preparation process of ultra-high doping concentration and the secondary epitaxial process of the light-emitting area. High doping is very likely to cause internal defects in the material, affecting reliability, and the doped atoms have a strong absorption effect on light. The position of the highly doped tunnel junction material layer must be accurately controlled at the standing wave node position of the oscillating light. A position deviation of several nanometers will cause a significant increase in the absorption coefficient of the laser, causing its light-emitting performance to decay sharply. Therefore, the current long-wavelength VCSEL lasers are limited by the above-mentioned preparation process, are very difficult to develop, and have extremely high manufacturing costs.

[0039] The long-wavelength vertical cavity surface emitting semiconductor laser provided by the present invention includes, from bottom to top, a DBR reflector, a lower current injection layer, a light-emitting area, an upper current injection layer and a reflection grating, wherein the DBR reflector and the reflection grating are arranged relative to each other, and the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector. At this time, the light generated by the light-emitting area located between the reflection grating and the DBR reflector will oscillate between the reflection grating and the DBR reflector to generate laser, and because the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector, the light will be emitted from the reflection grating to the semiconductor laser, and the position of the above-mentioned reflection grating is the position of the light-emitting hole in the semiconductor laser. Since the reflection grating has a simple structure and a simple preparation process, the preparation of the light-emitting hole of the long-wavelength VCSEL laser can be greatly simplified, thereby reducing the preparation cost of the long-wavelength VCSEL laser.

[0040] In order to enable those skilled in the art to better understand the scheme of the present invention, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0041] Please refer to Figure 1 , Figure 1 A schematic structural diagram of a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by an embodiment of the present invention.

[0042] See also Figure 1 In an embodiment of the present invention, a long wavelength vertical cavity surface emitting semiconductor laser comprises a DBR reflector 1; a lower current injection layer 2 located on the surface of the DBR reflector 1; a light emitting area 3 located on the surface of the lower current injection layer 2 facing away from the DBR reflector 1; an upper current injection layer 4 located on the surface of the light emitting area 3 facing away from the DBR reflector 1; a reflection grating 5 with a preset light emitting area located on the surface of the upper current injection layer 4 facing away from the DBR reflector 1; the wavelength of reflected light of the reflection grating 5 is the same as the wavelength of reflected light of the DBR reflector 1, and the reflectivity of the reflection grating 5 is less than the reflectivity of the DBR reflector 1.

[0043] The above-mentioned DBR reflector 1 is usually formed by stacking multiple layers of films with different reflectivities in a periodic arrangement. The specific structure of the DBR reflector 1 can refer to the prior art and will not be described in detail here. In the embodiment of the present invention, the DBR reflector 1 has a preset reflected light wavelength, that is, the DBR reflector 1 has an extremely high reflectivity for light of a preset wavelength, and the light of the preset wavelength is the wavelength of the laser that can be generated by the semiconductor laser.

[0044] The lower current injection layer 2 is located on the surface of the DBR reflector 1 and is usually used to inject carriers into the light emitting area 3. The specific material of the lower current injection layer 2 can be referred to the prior art and will not be described in detail here.

[0045] The above-mentioned light-emitting area 3 is located on the surface of the lower current injection layer 2 facing away from the DBR reflector 1, and the upper current injection layer 4 is located on the surface of the light-emitting area 3 facing away from the DBR reflector 1. At this time, the lower current injection layer 2 and the upper current injection layer 4 are arranged relative to each other, and the lower current injection layer 2 and the upper current injection layer 4 will clamp the light-emitting area 3, thereby forming a kind of sandwich structure. The upper current injection layer 4 is usually used to inject carriers into the light-emitting area 3, and the light-emitting area 3 can generate lasers. Specifically, the carriers transmitted by the lower current input layer and the carriers transmitted by the upper current injection layer 4 will be coupled in the light-emitting area 3, thereby producing light of a preset wavelength. It should be noted that the properties of the carriers transmitted by the lower current input layer and the carriers transmitted by the upper current injection layer 4 are usually opposite. The specific structure and specific material of the light-emitting area 3 and the upper current injection layer 4 can refer to the prior art, and will not be repeated here. Generally, the light-emitting area 3 in the embodiment of the present invention is usually a quantum well light-emitting area 3 or a quantum dot light-emitting area 3. That is, the structure of the light emitting area 3 can be a quantum well structure or a quantum dot structure, which is not specifically limited in the embodiment of the present invention. Of course, in the embodiment of the present invention, the specific structure of the light emitting area 3 is not specifically limited, as long as it can generate light of a preset wavelength.

[0046] The above-mentioned reflection grating 5 is located in the preset light emitting area on the surface of the upper current injection layer 4 facing away from the DBR reflector 1. Usually, the surface of the upper current input layer is divided into a light emitting area and a non-light emitting area, wherein the light emitting area is the preset position of the light emitting hole in the semiconductor laser, and in the non-light emitting area, no laser will be emitted from the semiconductor laser from the above-mentioned non-light emitting area. Specifically, the above-mentioned reflection grating 5 is only arranged in the light emitting area pre-divided on the surface of the upper current injection layer 4. The above-mentioned reflection grating 5 and the DBR reflector 1 are arranged relative to each other, and the light generated by the light emitting area 3 located in the area between the reflection grating 5 and the DBR reflector 1 will oscillate between the reflection grating 5 and the DBR reflector 1 to generate laser. It should be noted that the above-mentioned reflection grating 5 is also a structure with extremely high reflectivity for light of a specific wavelength. The specific structure of the reflection grating 5 can refer to the prior art and will not be repeated here.

[0047] Specifically, the wavelength of the reflected light of the above-mentioned reflection grating 5 needs to be the same as the wavelength of the reflected light of the DBR reflector 1, and usually needs to be equal to the wavelength of the light emitted by the light-emitting area 3, so as to ensure that the light can oscillate between the reflection grating 5 and the DBR reflector 1. At the same time, the reflectivity of the above-mentioned reflection grating 5 needs to be less than the reflectivity of the DBR reflector 1, so as to ensure that the laser can eventually be emitted from the semiconductor laser from the reflection grating 5. Specifically, in the embodiment of the present invention, the reflectivity of the above-mentioned reflection grating 5 is usually in the range of 95% to 99%, including the end value. That is, the reflectivity of the reflection grating 5 can be exactly 95% or 99%, and any value in between. Of course, in the embodiment of the present invention, the reflectivity of the DBR reflector 1 needs to be greater than the reflectivity of the reflection grating 5.

[0048] Typically, in the embodiment of the present invention, the surface of the lower current injection layer 2 facing away from the DBR reflector 1 has a stepped surface, and the stepped surface is provided with a lower electrode 6; the surface of the upper current injection layer 4 facing away from the DBR reflector 1 is provided with an upper electrode 7.

[0049] The lower electrode 6 needs to be electrically connected to the lower current injection layer 2, and the upper electrode 7 needs to be electrically connected to the upper current injection layer 4, so that the operator can inject current into the light-emitting area 3 through the upper electrode 7 and the lower electrode 6. Specifically, the size of the light-emitting area 3 is smaller than the size of the lower current injection layer 2, so that a step surface is formed on the surface of the lower current injection layer 2 on the side facing away from the DBR reflector 1, and the lower electrode 6 is arranged on the step surface so that the lower electrode 6 and the lower current injection layer 2 are in contact with each other to form an electrical connection. The upper electrode 7 is usually arranged on the surface of the upper current injection layer 4 on the side facing away from the DBR reflector 1, and is usually arranged in the non-light-emitting area on the surface of the upper current injection layer 4 on the side facing away from the DBR reflector 1, so as to be in contact with the upper current injection layer 4 to form an electrical connection. During use, the operator will supply power to the semiconductor laser through the upper electrode 7 and the lower electrode 6 to inject carriers into the light-emitting area 3 to generate light, which will oscillate between the reflection grating 5 and the DBR reflector 1, and the formed laser will emit the semiconductor laser from the reflection grating 5.

[0050] A long-wavelength vertical cavity surface emitting semiconductor laser provided by an embodiment of the present invention includes, from bottom to top, a DBR reflector 1, a lower current injection layer 2, a light-emitting area 3, an upper current injection layer 4 and a reflection grating 5, wherein the DBR reflector 1 and the reflection grating 5 are arranged opposite to each other, and the wavelength of the reflected light of the reflection grating 5 is the same as the wavelength of the reflected light of the DBR reflector 1, and the reflectivity of the reflection grating 5 is less than the reflectivity of the DBR reflector 1. At this time, the light generated by the light-emitting area 3 located between the reflection grating 5 and the DBR reflector 1 will oscillate between the reflection grating 5 and the DBR reflector 1 to generate laser light, and because the reflectivity of the reflection grating 5 is less than the reflectivity of the DBR reflector 1, the light will be emitted from the reflection grating 5 to the semiconductor laser, and the position of the above-mentioned reflection grating 5 is the position of the light-emitting hole in the semiconductor laser. Since the structure of the reflection grating 5 is simple and the preparation process is simple, the preparation of the light-emitting hole of the long-wavelength VCSEL laser can be greatly simplified, thereby reducing the preparation cost of the long-wavelength VCSEL laser.

[0051] The specific structure of a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by the present invention will be described in detail in the following invention embodiments.

[0052] Please refer to Figure 2 , Figure 2 The present invention provides a schematic structural diagram of a specific long-wavelength vertical-cavity surface-emitting semiconductor laser.

[0053] Different from the above-mentioned invention embodiment, the present invention embodiment further specifically defines the structure of the long-wavelength vertical cavity surface emitting semiconductor laser on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0054] See also Figure 2 In the embodiment of the present invention, at least two light-emitting areas 3 are arranged on the surface of the lower current injection layer 2 facing away from the DBR reflector 1, and adjacent light-emitting areas 3 are isolated from each other; a corresponding upper current injection layer 4 is arranged on the surface of any light-emitting area 3 facing away from the DBR reflector 1; and a corresponding reflection grating 5 is arranged on the light-emitting area of ​​any upper current injection layer 4 facing away from the DBR reflector 1.

[0055] In an embodiment of the present invention, the long wavelength vertical cavity surface emitting semiconductor laser has a plurality of light emitting points, wherein Figure 2The structure shown takes two light-emitting points as an example. Of course, in the embodiment of the present invention, more light-emitting points can be set to form a long-wavelength VCSEL array structure with any number of light-emitting points. Specifically, in the embodiment of the present invention, at least two light-emitting areas 3 are set on the surface of the lower current injection layer 2 facing away from the DBR reflector 1, that is, multiple light-emitting points share one lower current injection layer 2, and the corresponding multiple light-emitting points usually also share the lower electrode 6 located on the surface of the lower current injection layer 2.

[0056] In the embodiment of the present invention, each light-emitting area 3 is provided with a corresponding upper current injection layer 4 on the surface facing away from the DBR reflector 1, and each upper current injection layer 4 is provided with a corresponding reflection grating 5 on the surface facing away from the DBR reflector 1. Except for the shared lower current injection layer 2, each structure stacked by the light-emitting area 3, the upper current injection layer 4 and the reflection grating 5 constitutes a light-emitting point that can emit laser. That is, the long-wavelength vertical cavity surface emitting semiconductor laser provided in the embodiment of the present invention is equivalent to being composed of a plurality of small long-wavelength vertical cavity surface emitting semiconductor lasers, wherein the plurality of small long-wavelength vertical cavity surface emitting semiconductor lasers share the same DBR reflector 1 and the same lower current injection layer 2.

[0057] It should be noted that the adjacent light zones need to be isolated from each other to ensure that there is no current crosstalk between adjacent light-emitting points. Accordingly, at least one upper electrode 7 is usually provided on the surface of each upper current injection layer 4 to ensure that each light-emitting point can be used.

[0058] A long wavelength vertical cavity surface emitting semiconductor laser provided in an embodiment of the present invention can integrate multiple light-emitting points in a long wavelength vertical cavity surface emitting semiconductor laser by setting a plurality of light-emitting areas 3 isolated from each other and sequentially setting an upper current injection layer 4 and a reflection grating 5 on the surface of each light-emitting area 3, thereby forming a long wavelength vertical cavity surface emitting semiconductor laser array.

[0059] The specific structure of a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by the present invention will be described in detail in the following invention embodiments.

[0060] Please refer to Figure 3 , Figure 3 A schematic structural diagram of another specific long-wavelength vertical-cavity surface-emitting semiconductor laser provided in an embodiment of the present invention.

[0061] Different from the above-mentioned invention embodiment, the present invention embodiment further specifically defines the structure of the long-wavelength vertical cavity surface emitting semiconductor laser on the basis of the above-mentioned invention embodiment. The rest of the contents have been described in detail in the above-mentioned invention embodiment and will not be repeated here.

[0062] See also Figure 3In an embodiment of the present invention, at least two mutually isolated reflection gratings 5 ​​are arranged on the surface of the upper current injection layer 4 facing away from the DBR reflector 1, and the distance between adjacent reflection gratings 5 ​​is not greater than the diffusion distance of the current in the upper current injection layer 4; the distance between adjacent reflection gratings 5 ​​is not greater than the diffusion distance of the current in the lower current injection layer 2.

[0063] In the embodiment of the present invention, at least two mutually isolated reflection gratings 5 ​​are provided on the surface of the upper current injection layer 4 facing away from the DBR reflector 1, and each of the reflection gratings 5 ​​corresponds to a light-emitting point, and the light-emitting points share the DBR reflector 1, the lower current injection layer 2, the light-emitting area 3 and the upper current injection layer 4. At this time, since the light-emitting area 3 is shared between different light-emitting points, it is equivalent to that the light-emitting points are not isolated from each other, and the light generated by the light-emitting area 3 will propagate between different light-emitting points.

[0064] At this time, in the embodiment of the present invention, the light generated by the light-emitting area 3 will not only oscillate between the DBR reflector 1 and the different reflection gratings 5, but also a certain proportion of the light will be transmitted between adjacent light-emitting points in the lateral direction. At this time, the lasers oscillating between the DBR reflector 1 and the different reflection gratings 5 ​​will be locked with each other, achieving oscillation in the same phase, and finally forming two coherent laser outputs with the same phase. Accordingly, the semiconductor laser provided in the embodiment of the present invention can form a long-wavelength VCSEL coherent array with any number of light-emitting points.

[0065] It should be noted that, in the embodiment of the present invention, the distance between adjacent reflection gratings 5 ​​needs to be no greater than the diffusion distance of the current in the upper current injection layer 4; meanwhile, the distance between adjacent reflection gratings 5 ​​needs to be no greater than the diffusion distance of the current in the lower current injection layer 2. Limiting the distance between adjacent reflection gratings 5 ​​within the above range can ensure that there is electrically stable current injection under both reflection gratings 5, thereby achieving laser oscillation and ensuring the output of multiple coherent laser beams with the same phase.

[0066] A long-wavelength vertical-cavity surface-emitting semiconductor laser provided in an embodiment of the present invention can output multiple coherent laser beams with the same phase by only setting a plurality of reflection gratings 5 ​​on the surface of the upper current input layer and controlling the distance between adjacent reflection gratings 5, thereby forming a long-wavelength VCSEL coherent array.

[0067] A method for preparing a long wavelength vertical cavity surface emitting semiconductor laser provided by the present invention is introduced below. The preparation method described below and the structure of the long wavelength vertical cavity surface emitting semiconductor laser described above can correspond to each other.

[0068] Please refer to Figure 4 , Figure 4The present invention provides a flowchart of a method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser.

[0069] See also Figure 4 In an embodiment of the present invention, the method for preparing the long wavelength vertical cavity surface emitting semiconductor laser comprises:

[0070] S101: growing a DBR reflector through an epitaxial growth process.

[0071] In this step, a DBR reflector is usually epitaxially grown on the substrate surface based on an epitaxial growth process. The structure of the DBR reflector and the specific epitaxial growth process can be referred to the prior art, and will not be described in detail here.

[0072] S102: epitaxially growing a lower current injection layer on the surface of the DBR reflector.

[0073] S103: epitaxially growing a light emitting region on the surface of the lower current injection layer facing away from the DBR reflector.

[0074] S104: epitaxially growing a current injection layer on the surface of the light emitting region facing away from the DBR reflector.

[0075] S105: epitaxially growing a grating layer on the surface of the upper current injection layer region facing away from the DBR reflector.

[0076] In the embodiment of the present invention, usually based on the epitaxial growth process, the lower current injection layer, the light emitting area, the upper current injection layer and the grating layer are epitaxially grown in sequence along the normal direction of the DBR reflector on the surface of the DBR reflector. The specific structures of the lower current injection layer, the light emitting area and the upper current injection layer are described in detail in the above-mentioned embodiment of the invention, and will not be repeated here.

[0077] The grating layer is a pre-structure of the reflective grating in the embodiment of the present invention. In the subsequent steps, the grating layer will be etched to prepare the reflective grating.

[0078] S106: etching the grating layer to remove the grating layer in the non-light emitting area on the surface of the upper current injection layer facing away from the DBR reflector.

[0079] In this step, the grating layer in the non-light-emitting area on the surface of the upper current injection layer facing away from the DBR reflector is usually removed by mask preparation and dry etching, and only the grating layer in the light-emitting area on the surface of the upper current injection layer facing away from the DBR reflector is retained. The purpose of this step is to determine the position of the final light-emitting hole. In this step, the position of the grating layer is retained, that is, the position of the light-emitting hole in the semiconductor laser.

[0080] S107: etching the grating layer in the light emitting area on the surface of the upper current injection layer facing away from the DBR reflector into a reflection grating to produce a long wavelength vertical cavity surface emitting semiconductor laser.

[0081] In the embodiment of the present invention, the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector. The specific parameters of the reflection grating and the DBR reflector have been described in detail in the above-mentioned embodiment of the invention, and will not be repeated here.

[0082] In this step, the remaining grating layer in S106 is usually etched into a reflective grating by grating mask preparation and dry etching to complete the preparation of a long wavelength vertical cavity surface emitting semiconductor laser. The specific preparation process of the reflective grating can refer to the prior art and will not be repeated here.

[0083] A method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser provided in an embodiment of the present invention, wherein the prepared long-wavelength vertical cavity surface emitting semiconductor laser includes, from bottom to top, a DBR reflector, a lower current injection layer, a light-emitting area, an upper current injection layer and a reflection grating, wherein the DBR reflector and the reflection grating are arranged relative to each other, and the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector. At this time, the light generated by the light-emitting area located between the reflection grating and the DBR reflector will oscillate between the reflection grating and the DBR reflector to generate laser, and since the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector, the light will be emitted from the reflection grating to the semiconductor laser, and the position of the above-mentioned reflection grating is the position of the light-emitting hole in the semiconductor laser. Since the structure of the reflection grating is simple and the preparation process is simple, the preparation of the light-emitting hole of the long-wavelength VCSEL laser can be greatly simplified, thereby reducing the preparation cost of the long-wavelength VCSEL laser.

[0084] The specific contents of the method for preparing a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by the present invention will be described in detail in the following invention embodiments.

[0085] Please refer to Figure 5 , Figure 5 The present invention provides a flowchart of a specific method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser.

[0086] See also Figure 5 In an embodiment of the present invention, the method for preparing the long wavelength vertical cavity surface emitting semiconductor laser comprises:

[0087] S201: growing a DBR reflector through an epitaxial growth process.

[0088] S202: epitaxially growing a lower current injection layer on the surface of the DBR reflector.

[0089] S203: epitaxially growing a light-emitting region on the surface of the lower current injection layer facing away from the DBR reflector.

[0090] S204: epitaxially growing a current injection layer on the surface of the light emitting region facing away from the DBR reflector.

[0091] S205: epitaxially growing a grating layer on the surface of the upper current injection layer region facing away from the DBR reflector.

[0092] The above S201 to S205 are basically the same as S101 to S105 in the above invention embodiment. Please refer to the above invention embodiment for details, which will not be repeated here.

[0093] S206: etching the grating layer, the upper current injection layer and the light emitting region in sequence from the surface of the grating layer facing away from the DBR reflector to form a step surface on the surface of the lower current injection layer facing away from the DBR reflector.

[0094] In this step, the above structure is usually etched in sequence by a mask preparation plus dry etching method to expose the surface of the lower current injection layer on the side facing away from the DBR reflector. At this time, a step surface will be formed on the surface of the lower current injection layer on the side facing away from the DBR reflector. For the specific etching process, reference can be made to the prior art, which will not be described in detail here. In this step, the grating layer, the upper current injection layer and the light-emitting area will be etched in sequence from above the entire semiconductor laser to expose part of the lower current injection layer.

[0095] It should be noted that in this step, if one wants to eventually form the above-mentioned long-wavelength vertical-cavity surface-emitting semiconductor laser array, the light-emitting area, the upper current injection layer and the grating layer will be etched into a specific columnar array structure, and in subsequent steps, a reflective grating will be prepared on the surface of each upper current injection layer to form a long-wavelength vertical-cavity surface-emitting semiconductor laser array.

[0096] S207: Setting a lower electrode on the step surface.

[0097] In this step, a lower electrode is disposed on the step surface exposed in S206, and the lower electrode generally needs to form an ohmic contact with the lower current injection layer to reduce the resistance between the lower electrode and the lower current injection layer. The specific preparation process of the lower electrode can refer to the prior art and will not be described here.

[0098] S208: etching the grating layer to remove the grating layer in the non-light emitting area on the surface of the upper current injection layer facing away from the DBR reflector.

[0099] This step is basically the same as S106 in the above invention embodiment. Please refer to the above invention embodiment for details, which will not be described again. In this step, part of the grating layer is etched to expose part of the upper current injection layer.

[0100] It should be noted that in this step, if the above-mentioned long wavelength VCSEL coherent array is to be finally formed, it is necessary to etch out multiple grating layers that meet the preset spacing in this step, and in the subsequent steps, the multiple grating layers are etched into reflective gratings to form the long wavelength VCSEL coherent array.

[0101] S209: An upper electrode is disposed in a non-light emitting area on a surface of the upper current injection layer facing away from the DBR reflector.

[0102] In this step, an upper electrode is disposed on the exposed surface of the upper current injection layer, and the upper electrode generally needs to form an ohmic contact with the upper current injection layer to reduce the resistance between the upper electrode and the upper current injection layer. The specific preparation process of the upper electrode can refer to the prior art and will not be described here.

[0103] S210: etching the grating layer in the light emitting area on the surface of the upper current injection layer facing away from the DBR reflector into a reflection grating to produce a long wavelength vertical cavity surface emitting semiconductor laser.

[0104] This step is basically the same as S107 in the above-mentioned embodiment of the invention, and the details have been described in detail in the above-mentioned embodiment of the invention, so they will not be repeated here.

[0105] The method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser provided in an embodiment of the present invention can specifically prepare a long-wavelength vertical cavity surface emitting semiconductor laser array or a long-wavelength VCSEL coherent array.

[0106] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0107] Professionals may further appreciate that the units and algorithm steps of each example described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, computer software, or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the composition and steps of each example have been generally described in the above description according to function. Whether these functions are performed in hardware or software depends on the specific application and design constraints of the technical solution. Professionals and technicians may use different methods to implement the described functions for each specific application, but such implementation should not be considered to be beyond the scope of the present invention.

[0108] The steps of the method or algorithm described in conjunction with the embodiments disclosed herein may be implemented directly using hardware, a software module executed by a processor, or a combination of the two. The software module may be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.

[0109] Finally, it should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the presence of other identical elements in the process, method, article or device including the elements.

[0110] The above is a detailed introduction to a long-wavelength vertical-cavity surface-emitting semiconductor laser and a method for preparing a long-wavelength vertical-cavity surface-emitting semiconductor laser provided by the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. It should be pointed out that for ordinary technicians in this technical field, without departing from the principles of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A long wavelength vertical cavity surface emitting semiconductor laser, characterized in that: include: DBR reflector; A lower current injection layer located on the surface of the DBR reflector; A light emitting area located on a surface of the lower current injection layer facing away from the DBR reflector; An upper current injection layer located on a surface of the light emitting area facing away from the DBR reflector; A reflection grating in a preset light-emitting area on a surface of the upper current injection layer facing away from the DBR reflector; the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector; At least two mutually isolated reflection gratings are arranged on the surface of the upper current injection layer facing away from the DBR reflector, and the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the upper current injection layer; the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the lower current injection layer; Each of the reflection gratings corresponds to a light-emitting point, and different light-emitting points share a light-emitting area, and the light generated by the light-emitting area propagates between different light-emitting points; the lasers oscillating between the DBR reflector and different reflection gratings are locked to each other to achieve oscillation in the same phase, forming coherent laser output with the same phase; forming a long-wavelength VCSEL coherent array with a preset number of light-emitting points.

2. The semiconductor laser according to claim 1, characterized in that The reflectivity of the reflection grating ranges from 95% to 99%, including end points.

3. The semiconductor laser according to claim 1, characterized in that The surface of the lower current injection layer facing away from the DBR reflector has a step surface, and the step surface is provided with a lower electrode; the surface of the upper current injection layer facing away from the DBR reflector is provided with an upper electrode.

4. The semiconductor laser according to claim 3, characterized in that The light-emitting region is a quantum well light-emitting region or a quantum dot light-emitting region.

5. A method for preparing a long-wavelength vertical cavity surface emitting semiconductor laser, characterized in that: include: Growing the DBR reflector by an epitaxial growth process; epitaxially growing a lower current injection layer on the surface of the DBR reflector; Epitaxially growing a light-emitting region on the surface of the lower current injection layer facing away from the DBR reflector; Epitaxially growing an upper current injection layer on the surface of the light emitting region facing away from the DBR reflector; Epitaxially growing a grating layer on the surface of the upper current injection layer region facing away from the DBR reflector; Etching the grating layer to remove the grating layer in the non-light emitting area on the surface of the upper current injection layer facing away from the DBR reflector; Etching the grating layer of the light emitting area on the surface of the upper current injection layer facing away from the DBR reflector into a reflection grating to manufacture the long-wavelength vertical cavity surface emitting semiconductor laser; A long-wavelength VCSEL coherent array with a preset number of light-emitting points is formed; the wavelength of the reflected light of the reflection grating is the same as the wavelength of the reflected light of the DBR reflector, and the reflectivity of the reflection grating is less than the reflectivity of the DBR reflector; At least two mutually isolated reflection gratings are arranged on the surface of the upper current injection layer facing away from the DBR reflector, and the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the upper current injection layer; the distance between adjacent reflection gratings is not greater than the diffusion distance of the current in the lower current injection layer; Each of the reflection gratings corresponds to a light-emitting point, and different light-emitting points share a light-emitting area, and the light generated by the light-emitting area propagates between different light-emitting points; the lasers oscillating between the DBR reflector and different reflection gratings are mutually locked to achieve oscillation in the same phase, forming coherent laser output with the same phase.

6. The method according to claim 5, characterized in that After epitaxially growing a grating layer on the surface of the upper current injection layer region facing away from the DBR reflector, the method further comprises: The grating layer, the upper current injection layer and the light-emitting region are sequentially etched from the surface of the grating layer on the side facing away from the DBR reflector to form a step surface on the surface of the lower current injection layer on the side facing away from the DBR reflector; Disposing a lower electrode on the surface of the step surface; After etching the grating layer, the method further comprises: An upper electrode is arranged in a non-light emitting area on a surface of the upper current injection layer facing away from the DBR reflector.

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