Surface emitting laser

Abstract

The embodiment of the application relates to a surface emitting laser, comprising: a substrate; a bottom mirror structure, an active layer and a top mirror structure arranged on the substrate; a grating structure arranged on the top mirror structure; the projection shape of the grating structure on the substrate is designed to adjust the far-field spot shape or far-field image of the surface emitting laser. The application realizes the purpose of adjusting the far-field spot shape or far-field image of the laser by controlling the projection shape of the grating structure on the substrate, retains the polarization control ability of the grating, and expands the application scenario of the grating.

Description

Technical Field

[0001] This application relates to the field of semiconductor laser technology, and in particular to a surface-emitting laser. Background Technology

[0002] With the continuous development of semiconductor technology, surface-emitting lasers, such as vertical-cavity surface-emitting lasers (VCSELs), are widely used in optical communication, optical interconnection and optical sensing due to their easy integration characteristics.

[0003] Gratings have proven effective for polarization control of VCSELs. However, there is a significant market demand for flat-top infrared illumination (IR) projection modules in numerous smart devices, such as smartphones. These modules play a crucial role in applications such as TOF measurement and security camera equipment, with the vertical-cavity surface-emitting laser (VCSEL) being the core component. Existing methods for forming flat-top far-field images mainly involve integrating diffusers or designing emission apertures. This application aims to achieve the aforementioned objective by improving the grating. Summary of the Invention

[0004] Therefore, it is necessary to provide a surface-emitting laser to address the aforementioned technical problems.

[0005] In a first aspect, this application provides a surface-emitting laser, comprising:

[0006] Substrate;

[0007] A bottom reflector structure, an active layer, and a top reflector structure disposed on the substrate;

[0008] A grating structure is disposed on the top reflector structure; the projection shape of the grating structure on the substrate is designed to adjust the far-field spot shape or far-field image of the surface-emitting laser.

[0009] In one embodiment, the grating structure includes a grating base layer and multiple etching channels formed by etching the grating base layer.

[0010] In one embodiment, the projection shape of the grating structure on the substrate is rectangular, the far-field image of the surface-emitting laser after adjustment by the grating structure is a flat-top far-field image, and the grating structure is configured to control the output light polarization mode of the surface-emitting laser.

[0011] In one embodiment, at least two sides of the rectangle are recessed toward the interior of the rectangle.

[0012] In one embodiment, the shorter side of the rectangle is recessed towards the interior of the rectangle; or

[0013] The long side of the rectangle is recessed towards the interior of the rectangle; or

[0014] Both the long and short sides of the rectangle are recessed towards the interior of the rectangle.

[0015] In one embodiment, at least two sides are recessed into the rectangle to different degrees.

[0016] In one embodiment, the projected shape of the recess on the substrate is an arc, a rectangle, or a triangle.

[0017] In one embodiment, the projection shape of the grating structure onto the substrate is irregular to adjust the far-field spot shape of the surface-emitting laser.

[0018] In one embodiment, it further includes:

[0019] A photoelectric confinement layer is formed in the top reflector structure, the photoelectric confinement layer including a light-emitting aperture for defining the light-emitting region of the surface-emitting laser;

[0020] The projection of the irregularly shaped grating structure onto the substrate and the projection of the light-emitting aperture onto the substrate at least partially overlap.

[0021] In one embodiment, the grating structure is a subwavelength grating structure.

[0022] The aforementioned surface-emitting laser achieves the purpose of adjusting the shape of the laser's far-field spot or far-field image by controlling the projection shape of the grating structure on the substrate. This retains the polarization control capability of the grating while expanding the application scenarios of the grating.

[0023] Secondly, this application provides a VCSEL chip, including at least one laser array; the laser array includes multiple surface-emitting lasers as described above; the laser array is a regularly arranged array, or a randomly arranged array, or an array with multiple addressable subarrays.

[0024] Thirdly, this application provides a light source for a lidar system, including at least one vertical cavity surface-emitting laser as described above or at least one VCSEL chip as described above.

[0025] Fourthly, this application provides a lidar system, including a transmitting component and a receiving component, wherein the transmitting component employs the light source described above for lidar systems. Attached Figure Description

[0026] Figure 1This is a schematic diagram of the structure of a surface-emitting laser in one embodiment of this application;

[0027] Figures 2a-2e for Figure 1 A schematic diagram showing the relative positional relationship between OA and different grating patterns in the embodiments;

[0028] Figure 3 This is a schematic diagram of the structure of a surface-emitting laser in another embodiment of this application.

[0029] The objectives, features, and advantages of this invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0030] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0031] It is understood that the terms "first," "second," etc., used in this application may be used herein to describe various elements, but these elements are not limited by these terms. These terms are only used to distinguish one element from another. For example, without departing from the scope of this application, a first client may be referred to as a second client, and similarly, a second client may be referred to as a first client.

[0032] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. "Multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified. "Several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0033] Based on this, please refer to Figures 1-3 This application provides a surface-emitting laser, comprising: a substrate 10; a bottom mirror structure 20, an active layer 30, and a top mirror structure 40 disposed on the substrate 10; a grating structure 50 disposed on the top mirror structure 40; the grating structure 50 includes a base layer 510 and multiple etching channels EG formed by etching the grating base layer 510, wherein the projection contours of the multiple etching channels EG on the substrate 10 are (…). Figures 2a-2e The dashed box in the image is a rectangle, and the far-field image of the surface-emitting laser after adjustment by the grating structure 50 is a flat-top far-field image. The grating structure 50 is configured to control the polarization mode of the output light of the surface-emitting laser.

[0034] When the projection shape of the grating structure 50 on the substrate 10 is irregular ( Figure 2f ), grating structure 50 is used to adjust the far-field spot shape of the surface-emitting laser. Figure 2f The overall shape of the grating is such that the light-emitting area is larger on the left and smaller on the right, resulting in a non-regular shape for the final light spot. This allows for adjustment of the final light spot shape, expanding its application scenarios. When the surface-emitting laser has multiple emission apertures OA, this method can be used to adjust the overall emitted light spot shape. Furthermore, to achieve an irregular shape, at least most of the etched channels must be spaced from the edge of the emission aperture OA by a first preset distance D1, and the remaining etched channels must be spaced from the edge of the emission area by a second preset distance D2. The first preset distance D1 is greater than the second preset distance D2. The first preset distance D1 can be, for example, 0.5-1 μm, and the second preset distance D2 can be, for example, 0-0.5 μm; this application does not impose any limitations on this.

[0035] In this specific embodiment, please refer to Figure 1 and Figure 3 The bottom reflector structure 20 and the top reflector structure 40 define the resonant cavity structure of the surface-emitting laser of this application; that is, the region between the bottom reflector structure 20 and the top reflector structure 40 is the resonant cavity. The resonant cavity is used to generate standing waves, which are waves formed by the superposition of two coherent waves propagating in opposite directions along the same straight line. Specifically, when the two waves are in phase, their amplitudes are added together, forming antinodes (i.e., crests). When the two waves are out of phase, their amplitudes are subtracted, forming nodes (i.e., troughs). Therefore, the positions of the crests and troughs of the standing wave are fixed.

[0036] In one embodiment, the bottom mirror structure 20 may include a periodically stacked DBR structure, i.e., multiple mirrors with an optical thickness of one-quarter of the lasing wavelength, arranged alternately with high and low refractive indices. The top mirror structure 40 also includes a periodically stacked DBR structure, i.e., multiple mirrors with an optical thickness of one-quarter of the lasing wavelength, arranged alternately with high and low refractive indices. It is understood that the composition, stacking period number, etc., of the DBR structure of the bottom mirror structure 20 and the DBR structure of the top mirror structure 40 may be the same or different; this embodiment does not impose limitations. The materials of the top mirror structure 40 and the bottom mirror structure 20 may be electrically insulating dielectric materials, such as silicon nitride, silicon oxide, aluminum oxide, or titanium oxide. The materials of the top mirror structure 40 and the bottom mirror structure 20 may also be semiconductor materials, such as GaAs and AlGaAs.

[0037] The substrate 10 is made of materials including, but not limited to, GaAs, InP, and Si. The bottom mirror structure 20 and the top mirror structure 40 may include films with periodically varying refractive indices to achieve efficient reflection or transmission of light within a specific wavelength range. These films can be made of semiconductor materials, dielectric materials, or metal-dielectric hybrid materials. For example, the bottom mirror structure 20 may be an N-type semiconductor layer, and the top mirror structure 40 may be a P-type semiconductor layer. Alternatively, the bottom mirror structure 20 may be a P-type semiconductor layer, and the top mirror structure 40 may be an N-type semiconductor layer. Optionally, the materials of the N-type and P-type semiconductor layers may be, but are not limited to, GaAs, AlGaAs, etc. This is not a limitation; as long as the resonant cavity can be confined, it falls within the scope of this embodiment. Specifically, the resonant cavity structure may also include a photoelectric confinement layer formed in the top mirror structure 40, and the photoelectric confinement layer defines the emission aperture OA of the surface-emitting laser.

[0038] The active layer 30 may include one, two, three, or four active regions. Each active region may contain one or more multi-quantum-well structures. The multi-quantum-well structures are used to generate photons through stimulated emission, and the emitted photons are continuously reflected in the resonant cavity defined by the bottom mirror structure 20 and the top mirror structure 40, and are continuously amplified during the reflection process, thereby ultimately emitting laser light at a specific wavelength with sufficient energy.

[0039] The multiple quantum well structure is where laser gain amplification occurs. The center of the multiple quantum well structure can be aligned with the location of the strongest light field to achieve a greater amplification effect. Furthermore, when multiple multiple quantum well structures are included, their confinement factors within the same light field segment are within the same preset range; that is, the confinement factors of each multiple quantum well structure are maintained at the same level, ensuring that each multiple quantum well structure contributes similarly to the light emission. Understandably, similar light emission contributions mean more uniform current injection into each multiple quantum well structure, which helps reduce the device's threshold current, thereby reducing power consumption and extending its lifespan. Moreover, when each multiple quantum well structure contributes similarly to the light emission, the distribution of charge carriers within each multiple quantum well structure will be more uniform, which helps reduce carrier recombination losses, thereby improving the overall luminous efficiency of the device.

[0040] Typically, the number of photoelectric confinement layers is no greater than the number of active layers 30, for example, two, three, or four. The photoelectric confinement layer is used to define the light-emitting region of the surface-emitting laser. Specifically, the photoelectric confinement layer is located on the side of the corresponding active layer 30 away from the substrate 10 to restrict the flow of current, ensuring that the current flows only within the light-emitting region defined by the photoelectric confinement layer. This reduces unnecessary energy consumption, thereby reducing the threshold current and increasing the current density. Furthermore, the photoelectric confinement layer can also confine the light field within the light-emitting region defined by the photoelectric confinement layer, reducing light scattering and diffraction, thereby optimizing the device's divergence angle and improving beam quality. Typically, the photoelectric confinement layer is located at the position of lowest light field intensity, i.e., at the trough of the standing wave, giving it a smaller confinement factor, which helps to reduce the device's divergence angle.

[0041] The photoelectric confinement layer can include any one of the following: air-pillar type photoelectric confinement layer, oxide-confinement type photoelectric confinement layer, ion-implanted type photoelectric confinement layer, and tunnel junction type photoelectric confinement layer. Among them, the air-pillar type photoelectric confinement layer confines current and light through air pillars. The air pillars are hollow structures formed by dry etching technology, and their refractive index is lower than that of the surrounding semiconductor material, thus effectively confining light to the central region. The ion-implanted type photoelectric confinement layer alters the electrical properties of the semiconductor material by implanting ions, forming a high-resistivity region. The high-resistivity region can restrict the flow of current, thereby indirectly confining the light generation region.

[0042] In one embodiment, the oxide-confined photoelectric confinement layer includes an unoxidized region of AlGaAs material with a high Al content and an oxidized region of aluminum oxide material. The oxidized region is located outside the unoxidized region, and the unoxidized region forms a light-emitting region for effective current injection. The semiconductor layer of the unoxidized region in the photoelectric confinement layer can be understood as an opening (…). Figures 2a-2d The openings (OA) in the photoelectric confinement layer define the emission region of the surface-emitting laser. When current enters, it can only flow to the active layer 30 through the openings in the photoelectric confinement layer, thus confining the current injection path and optical mode field. Furthermore, the high-aluminum AlGaAs layer can be converted to aluminum oxide through a selective oxidation process to form the surrounding unoxidized region.

[0043] In one embodiment, the tunnel junction optoelectronic confinement layer includes at least one highly doped N-type structure layer and at least one highly doped P-type structure layer. Specifically, a potential barrier is formed between the highly doped N-type structure layer and the highly doped P-type structure layer, allowing electrons to tunnel through the barrier, thereby achieving lateral confinement of the current. In one embodiment, the materials of the N-type structure layer and the P-type structure layer are Al. x Ga 1-x As, the doping concentration of the N-type and P-type structural layers is greater than 1e 18 cm-3 , where 0≤x≤1.

[0044] In one embodiment, such as Figures 1-2d As shown, the projection outline (dashed frame) of the multiple etching paths EG etched on the grating substrate 510 in this application on the substrate 10 can be rectangular, and at least two sides of the rectangle are recessed toward the inside of the rectangle. The two short sides of the rectangle may be recessed toward the inside of the rectangle; or the two long sides of the rectangle may be recessed toward the inside of the rectangle; or both the two long sides and the two short sides of the rectangle may be recessed toward the inside of the rectangle. Figure 2a The image shows the case where the rectangle is not recessed. Figure 2b For the case where OA is an ellipse and its projected outline is a rectangle. Figures 2c-2e This refers to the case where both the two long sides and two short sides of the rectangle are concave towards the interior of the rectangle.

[0045] In one embodiment, the projected shape of the recess (not shown) on the substrate 10 may include, but is not limited to, an arc shape, a rectangle, or a triangle. Furthermore, at least two sides are recessed to different degrees towards the interior of the polygon. Figure 2e As shown, this is an example where the concavity is arc-shaped, and the long and short sides of the rectangle have different degrees of concavity. By converging the degree of concavity in the outer region of the projected contour (the long and short sides of the rectangle), the final far-field light intensity distribution is made into a flat-top far field, i.e., a uniform light intensity distribution. Furthermore, the concavity can also be triangular (…). Figure 2d ); or the depression can also be rectangular ( Figure 2c Under this concept, the concave shape can also be represented in other ways.

[0046] In one embodiment, the thickness of the remaining grating substrate 510 after etching is an integer multiple of a quarter wavelength to meet the light emission requirements. Furthermore, the grating structure 50 of this application can be a subwavelength grating structure.

[0047] In one embodiment, the grating structure 50 is disposed on the top reflector structure 40, or the grating structure 50 is part of the top reflector structure 40. Exemplarily, when the grating structure 50 is disposed on the top reflector structure 40, the material of the grating structure 50 may be silicon dioxide, silicon nitride, aluminum oxide, polymer dielectric, or another type of dielectric material; when the grating structure 50 is part of the top reflector structure 40, the material of the grating structure 50 may be gallium arsenide or indium phosphide, etc. Further, when the grating structure 50 is a dielectric material, the dielectric material is a layer that at least partially insulates the top metal 610 from one or more other layers or features (e.g., the sidewalls of a trench).

[0048] The aforementioned surface-emitting laser (SEL) achieves a flat-topped far-field image by setting a grating structure on the light-emitting surface, or controls the shape of the far-field spot by using the grating structure. The grating structure is obtained by etching the area within the emission aperture range of the SEL. This grating structure can also achieve polarization mode control, thus expanding the application of the grating. The optoelectronic separation design avoids the problems of excessive overall module size and current concentration caused by concave emission apertures, which are common with traditional packaging integration.

[0049] In one embodiment, to achieve the desired high reflectivity, an additional reflectivity supplement structure (not shown) can be designed to increase the reflectivity on one side of the surface-emitting laser, including the bottom mirror structure 20 (e.g., the top side of the surface-emitting laser). Without the reflectivity supplement structure, the efficiency of integrating optical elements (such as gratings) in a surface-emitting laser on top of an all-semiconductor DBR mirror is lower (e.g., compared to a top-emitting surface-emitting laser) due to the desired high reflectivity and reduced interaction between the cavity mode and optical elements. Reducing the number of mirror pairs in the top mirror structure 40 increases the coupling between the cavity mode and such optical elements. However, reducing the number of mirror pairs in the top mirror structure 40 reduces the reflectivity on the side of the surface-emitting laser including the top mirror structure. In a surface-emitting laser, the reflectivity supplement structure is used to increase the reflectivity on the side of the surface-emitting laser including the bottom mirror structure 20. Therefore, the number of mirror pairs in the bottom mirror structure 20 can be reduced, and the reflectivity supplement structure can be designed to mitigate the decrease in reflectivity caused by the reduction in the number of mirror pairs in the bottom mirror structure 20. In some embodiments, the reflectivity supplementation structure may include multiple DBR pairs or another type of mirror structure. In some embodiments, the reflectivity supplementation structure is formed of a dielectric material. Therefore, in some embodiments, the reflectivity supplementation structure includes multiple dielectric DBR pairs. For example, the reflectivity supplementation structure may include multiple SiO2 / SiNx mirror pairs, multiple SiO2 / titanium dioxide (TiO2) mirror pairs, or multiple Al2O3 / TiO2 mirror pairs, and other examples. In some embodiments, the thickness of the reflectivity supplementation structure may range from about 2.0 μm to about 4.0 μm, such as 2.5 μm. In some embodiments, the number of mirror pairs in the reflectivity supplementation structure ranges from three to eight mirror pairs.

[0050] Figure 3In this embodiment, the surface-emitting laser may further include a top metal 610, which is a top metal layer at the front side of the surface-emitting laser. In some embodiments, the top metal 610 may be a layer in electrical contact with the top mirror structure 40 (e.g., through a grating structure and vias in the top mirror structure 40). In some embodiments, the top metal 610 may serve as an anode for the surface-emitting laser. In some embodiments, the top metal 610 may include an electroplated metal (e.g., gold (Au)) and / or a seed metal used in the electroplating process.

[0051] In one embodiment, to achieve better ohmic contact, an ohmic contact metal (not shown) may also be formed on the surface of the top reflector structure 40. The ohmic contact metal is the top contact layer of the surface-emitting laser, which is in electrical contact with the top reflector structure 40, through which current can flow. In some embodiments, the ohmic contact metal is formed of a material optimized for contacting p-type semiconductors. Alternatively, in some embodiments, the ohmic contact metal may also be formed of a material optimized for contacting n-type semiconductors. In some embodiments, the thickness of the ohmic contact metal is in the range of about 0.2 μm to about 0.8 μm, such as 0.5 μm. In some embodiments, the ohmic contact metal has an annular shape, a slotted annular shape, a gear shape, or another type of circular or non-circular shape (e.g., depending on the design of the surface-emitting laser).

[0052] Figure 3 In this embodiment, the surface-emitting laser may further include a bottom metal 620, which is a bottom metal layer beneath the surface-emitting laser. In some embodiments, the bottom metal 620 may be a layer that is electrically in contact with the entire surface of the substrate 10. In some embodiments, the bottom metal 620 may serve as a cathode for the surface-emitting laser. In some embodiments, the bottom metal 620 may include an electroplated metal (e.g., gold (Au)) and / or a seed metal used in the electroplating process.

[0053] Furthermore, the surface-emitting laser may also include a proton-injected region (not shown), which is a region that prevents free carriers from reaching the edge of the trench and / or isolates adjacent surface-emitting lasers from each other (e.g., if the trench does not completely surround the surface-emitting lasers) and / or prevents free carriers from leaking from the sidewalls. The proton-injected region may include, for example, an ion implantation material, such as a hydrogen / proton implantation material or a similar implantation element, to reduce conductivity.

[0054] Figure 3 The number, arrangement, thickness, order, and symmetry of the layers are provided as examples. In practice, with... Figure 3Compared to the layers shown, a surface-emitting laser can include additional layers, fewer layers, different layers, layers with different structures, or layers with different arrangements. For example, in some embodiments, a surface-emitting laser can include a semiconductor layer (e.g., one or more p-type layers) above a grating structure. As another example, in some embodiments, a surface-emitting laser can include an air interface above a grating structure. Additionally or alternatively, a set of layers (e.g., one or more layers) of a surface-emitting laser can perform one or more functions described as being performed by another set of layers of a surface-emitting laser, and any layer can include more than one layer.

[0055] This application also provides a VCSEL chip, which includes at least one laser array. The laser array includes multiple surface-emitting lasers as described above. The laser array can be a regularly arranged array, a randomly arranged array, or an array with multiple addressable subarrays. Based on the aforementioned surface-emitting lasers, the VCSEL chip of this embodiment exhibits good reliability.

[0056] This application also provides a light source for a lidar system, including at least one surface-emitting laser as described above or at least one VCSEL chip as described above.

[0057] This application also provides a lidar system, including a transmitting component and a receiving component, wherein the transmitting component uses the light source described above for lidar systems.

[0058] The foregoing disclosure provides illustrations and descriptions, but is not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Modifications and variations may be made in light of the foregoing disclosure or may be derived from practice of the embodiments. Furthermore, any embodiments described herein may be combined unless the foregoing disclosure expressly provides for reasons why one or more embodiments may not be combined.

[0059] Even though specific combinations of features are listed in the claims and / or disclosed in the specification, these combinations are not intended to limit the disclosure of the various embodiments. In fact, many of these features can be combined in ways not specifically listed in the claims and / or disclosed in the specification. Although each dependent claim listed below may directly depend on only one claim, the disclosure of the various embodiments includes each dependent claim combined with each other claim in the claim set. As used herein, the phrase “at least one of” in the list of items refers to any combination of these items, including a single member. As an example, “at least one of: a, b, or c” is intended to cover a, b, c, ab, ac, bc, and abc, as well as any combination having multiple identical items.

[0060] When a component or one or more components (e.g., a laser emitter or one or more laser emitters) is described or required (within a single claim or across multiple claims) to perform or be configured to perform multiple operations, this language is intended to broadly cover a wide range of architectures and environments. For example, unless explicitly required otherwise (e.g., by using “first component” and “second component” or other language distinguishing components in the claims), this language is intended to cover a single component performing or configured to perform all operations, a group of components jointly performing or configured to perform all operations, a first component performing or configured to perform a first operation and a second component performing or configured to perform a second operation, or any combination of components performing or configured to perform operations. For example, when a claim takes the form “one or more components are configured to: perform X; perform Y; and perform Z,” the claim should be interpreted as meaning “one or more components are configured to perform X; one or more (possibly different) components are configured to perform Y; and one or more (possibly different) components are configured to perform Z.”

[0061] The elements, actions, or instructions used herein should not be construed as critical or necessary unless explicitly stated otherwise. Furthermore, as used herein, the articles “a” and “one” are intended to include one or more items and may be used interchangeably with “one or more.” Further, as used herein, the article “the” is intended to include one or more items referenced in combination with the article “the” and may be used interchangeably with “the one or more.” Additionally, as used herein, the term “set” is intended to include one or more items (e.g., related items, unrelated items, or a combination of related and unrelated items) and may be used interchangeably with “one or more.” Where only one item is intended, the phrase “only one” or similar language is used. Furthermore, as used herein, the terms “having,” “containing,” “with,” etc., are intended to be open-ended terms. Further, unless explicitly stated otherwise, the phrase “based on” is intended to mean “at least partially based on.” Furthermore, as used herein, unless otherwise expressly stated (e.g., when used in combination with “any one” or “only one of”), the term “or” is intended to be inclusive when used in series and can be used interchangeably with “and / or”. Further, for ease of description, spatially relative terms such as “below,” “lower,” “above,” “upper,” etc., may be used herein to describe the relationship of an element or feature to another element(s) or feature(s) illustrated in the accompanying drawings. In addition to the orientations depicted in the accompanying drawings, spatially relative terms are intended to cover different orientations of devices, apparatuses, and / or elements in use or operation. The device may be oriented in other ways (rotated 90 degrees or otherwise), and the spatially relative descriptors used herein shall be interpreted accordingly.

Claims

1. A surface-emitting laser, characterized in that, include: Substrate; A bottom mirror structure, an active layer, and a top mirror structure disposed on the substrate; A grating structure is disposed on the top reflector structure; The projection shape of the grating structure on the substrate is designed to adjust the far-field spot shape or far-field image of the surface-emitting laser.

2. The surface-emitting laser according to claim 1, characterized in that, The grating structure includes a grating base layer and multiple etching channels formed by etching the grating base layer.

3. The surface-emitting laser according to claim 2, characterized in that, The projection shape of the grating structure on the substrate is rectangular, and the far-field image of the surface-emitting laser after adjustment by the grating structure is a flat-top far-field image. The grating structure is configured to control the polarization mode of the output light of the surface-emitting laser.

4. The surface-emitting laser according to claim 3, characterized in that, At least two sides of the rectangle are recessed toward the interior of the rectangle.

5. The surface-emitting laser according to claim 4, characterized in that, The shorter side of the rectangle is recessed towards the interior of the rectangle; or The long side of the rectangle is recessed towards the interior of the rectangle; or Both the long and short sides of the rectangle are recessed towards the interior of the rectangle.

6. The surface-emitting laser according to claim 4, characterized in that, At least two sides are recessed into the rectangle to different degrees.

7. The surface-emitting laser according to claim 4, characterized in that, The projection shape of the recess on the substrate is an arc, a rectangle, or a triangle.

8. The surface-emitting laser according to claim 2, characterized in that, The projection shape of the grating structure on the substrate is irregular to adjust the far-field spot shape of the surface-emitting laser.

9. The surface-emitting laser according to claim 8, characterized in that, Also includes: A photoelectric confinement layer is formed in the top reflector structure, the photoelectric confinement layer including a light-emitting aperture for defining the light-emitting region of the surface-emitting laser; The projection of the irregularly shaped grating structure onto the substrate and the projection of the light-emitting aperture onto the substrate overlap at least partially.

10. The surface-emitting laser according to any one of claims 1-9, characterized in that, The grating structure is a subwavelength grating structure.

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