Surface emitting laser

Abstract

The embodiment of the invention relates to a surface emitting laser. The surface emitting laser comprises a substrate; the bottom reflector structure, the active layer and the top reflector structure are arranged on the substrate; the grating structure is arranged on the top reflecting mirror structure; the grating structure comprises a base layer and an injection layer obtained by performing ion injection on a partial region of the base layer, the refractive index of the injection layer is different from that of the base layer, and the grating structure is configured to control the polarization mode of output light of the surface emitting laser. By applying the scheme of the invention, the surface smoothness of the grating can be improved, and an almost planar grating structure is manufactured.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of semiconductor lasers, and in particular, to a surface-emitting laser. Background Art

[0002] For a surface-emitting laser, such as a vertical-cavity surface-emitting laser (VCSEL), the polarization direction of the output laser is usually random. In many application fields, laser output with a stable polarization direction is very important for the entire system. Therefore, a layer of high-contrast grating is usually fabricated additionally on the light-emitting side of the VCSEL for polarization control.

[0003] Currently, the grating is usually fabricated by a deposition + etching process, which will form a non-planar surface. Under normal circumstances, an additional layer of material needs to be fabricated on the surface of the grating to planarize it ideally. Summary of the Invention

[0004] Based on this, it is necessary to provide a surface-emitting laser for the above technical problems.

[0005] In a first aspect, the present application provides a surface-emitting laser, including:

[0006] A substrate;

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

[0008] A grating structure disposed on the top mirror structure; the grating structure includes a base layer and an implanted layer obtained by ion implanting a partial region of the base layer, and the refractive index of the implanted layer is different from that of the base layer. The grating structure is configured to control the output light polarization mode of the surface-emitting laser.

[0009] In one embodiment, the base layer includes any one of gallium arsenide, indium phosphide, and silicon dioxide.

[0010] In one embodiment, the implanted layer includes a plurality of strip patterns or a plurality of dot patterns; and / or

[0011] The strip patterns or dot patterns are uniformly distributed in the base layer.

[0012] In one embodiment, the sizes of at least some of the strip patterns are different from those of the remaining strip patterns; or

[0013] The sizes of at least some of the dot patterns are different from those of the remaining dot patterns.

[0014] In one embodiment, the sizes of all the strip patterns are the same; or the sizes of all the dot patterns are the same.

[0015] In one embodiment, the depth of the same strip pattern is less than the width of the strip pattern; or, the depth of the same dot pattern is less than the width of the dot pattern.

[0016] In one embodiment, the depth of the strip pattern or the dot pattern is not greater than the wavelength of the surface-emitting laser; and / or

[0017] The grating period of the grating structure is not greater than the wavelength of the surface-emitting laser.

[0018] In one embodiment, the depth of the injection layer is between 0.11λ - 0.26λ, where λ is the wavelength of the surface-emitting laser.

[0019] In one embodiment, the width of the injection layer is between approximately 0.09λ - 0.23λ, where λ is the wavelength of the surface-emitting laser.

[0020] In one embodiment, it further includes a dielectric layer formed on the grating structure; and / or

[0021] Ohmic contact metal above or below the grating structure or formed in the openings of the grating structure.

[0022] In one embodiment, the side of the grating structure facing away from the epitaxial structure is a plane.

[0023] In one embodiment, the refractive index of the base layer is greater than or equal to twice the refractive index of the injection layer.

[0024] In one embodiment, the material for ion implantation includes at least one of the following substances:

[0025] H+, O+, N+, Ar+.

[0026] For the above surface-emitting laser, by introducing ion implantation to fabricate a planarized grating, problems such as voids, protrusions, and difficulties in surface planarization introduced by surface unevenness caused by the existing mainstream process of fabricating gratings through deposition + etching can be avoided.

[0027] In a second aspect, the present application provides a VCSEL chip, including at least one laser array; the laser array includes a plurality of the above surface-emitting lasers; the laser array is a regularly arranged array, or a randomly arranged array, or an array having multiple addressable sub-arrays.

[0028] In a third aspect, the present application provides a light source for a lidar system, including at least one of the above vertical cavity surface-emitting lasers or at least one of the above VCSEL chips.

[0029] In a fourth aspect, the present application provides a lidar system, including a transmitting component and a receiving component, wherein the transmitting component uses the above-mentioned light source for a lidar system. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 Schematic diagram of the structure of a surface-emitting laser in an embodiment of the present application;

[0031] Figures 2a - 2e is Figure 1 Schematic diagram of the relative position relationship between OA and different grating patterns in an embodiment;

[0032] Figure 3 Schematic diagram of the structure before fabricating a grating structure in an embodiment;

[0033] Figure 4 Schematic diagram of the structure of a surface-emitting laser in another embodiment of the present application.

[0034] The realization of the object, functional features and advantages of the present invention will be further described with reference to the embodiments and the accompanying drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0035] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0036] It can be understood that the terms "first", "second", etc. used in the present 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 the present application, the first client may be referred to as the second client, and similarly, the second client may be referred to as the first client.

[0037] In addition, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one of the features. The meaning of "a plurality" is at least two, such as two, three, etc., unless otherwise specifically defined. The meaning of "several" is at least one, such as one, two, etc., unless otherwise specifically defined.

[0038] Based on this, the present application creatively proposes a preparation process for a planarized grating, aiming to solve the aforementioned technical problems.

[0039] In a first aspect, as Figure 1As shown in the figure, the present application provides a surface-emitting laser, including a substrate 10; a bottom mirror structure 110, an active layer 120, and a top mirror structure 130 disposed on the substrate 10;

[0040] a grating structure 140 disposed on the top mirror structure 130; the grating structure 140 includes a base layer 144 and an implanted layer 142 obtained by ion implanting a partial region of the base layer 144, the refractive index of the implanted layer 142 is different from that of the base layer 144, and the grating structure 140 is configured to control the output light polarization mode of the surface-emitting laser. The surface-emitting laser of the present application can be, for example, a vertical cavity surface-emitting laser. For ease of description, the vertical cavity surface-emitting laser will be taken as an example for subsequent description.

[0041] In this specific embodiment, reference can be made to Figure 1 and Figure 4 , the bottom mirror structure 110 and the top mirror structure 130 define the resonant cavity structure of the vertical cavity surface-emitting laser of the present application, that is, the region between the bottom mirror structure 110 and the top mirror structure 130 is the resonant cavity. The resonant cavity is used to generate a standing wave, which is a wave formed by the superposition of two coherent waves propagating in opposite directions on the same straight line. Specifically, when the phases of the two waves are the same, their amplitudes are added to form a wave crest (i.e., a wave peak). When the phases of the two waves are opposite, their amplitudes are subtracted to form a wave node (i.e., a wave trough). Therefore, the positions of the wave crests and wave troughs of the standing wave are fixed.

[0042] In one embodiment, the bottom mirror structure 110 may include a periodically stacked DBR structure, that is, it includes multiple mirrors with an optical thickness of a quarter of the lasing wavelength, and the multiple mirrors are alternately arranged according to high and low refractive indices. The top mirror structure 130 also includes a periodically stacked DBR structure, that is, multiple mirrors with an optical thickness of a quarter of the lasing wavelength, and the multiple mirrors are alternately arranged according to high and low refractive indices. It can be understood that the components, stacking periods, etc. of the DBR structure of the bottom mirror structure 110 and the DBR structure of the top mirror structure 130 can be the same or different, which is not limited in this embodiment. Among them, the materials of the top mirror structure 130 and the bottom mirror structure 110 can be dielectric materials with electrical insulation properties, such as silicon nitride, silicon oxide, aluminum oxide, or titanium oxide, etc. The materials of the top mirror structure 130 and the bottom mirror structure 110 can also be semiconductor materials, such as GaAs and AlGaAs.

[0043] Among them, the material of the substrate 10 includes but is not limited to GaAs, InP, Si, etc. The bottom mirror structure 110 and the top mirror structure 130 may include film layers with periodically varying refractive indices to achieve efficient reflection or transmission of light within a specific wavelength range. The film layers with periodically varying refractive indices can be composed of semiconductor materials, dielectric materials, metal-dielectric hybrid materials, etc. For example, the bottom mirror structure 110 can be an N-type semiconductor layer, and the top mirror structure 130 can be a P-type semiconductor layer. Another example is that the bottom mirror structure 110 can be a P-type semiconductor layer, and the top mirror structure 130 can be an N-type semiconductor layer. Optionally, the materials of the N-type semiconductor layer and the P-type semiconductor layer can be but are not limited to GaAs, AlGaAs, etc., which are not limited here as long as they can define the resonant cavity and fall within the protection scope of this embodiment. Specifically, the resonant cavity structure may further include an optical and electrical confinement layer 132, which is formed in the top mirror structure 130 and defines the light-emitting region.

[0044] The active layer 120 can include 1 active region, or 2 active regions, or 3 active regions, or 4 active regions. One or more multiple quantum well structures can be provided in each active region. The multiple quantum well structures are used to generate stimulated emission photons, and the emitted photons are continuously reflected in the resonant cavity defined by the bottom mirror structure 110 and the top mirror structure 130 and continuously enhanced during the reflection process, and finally emit laser light at a specific wavelength and with sufficient energy.

[0045] The multiple quantum well structure is the place where laser gain amplification occurs. The central position of the multiple quantum well structure can be aligned with the position where the optical field is the strongest to achieve a greater amplification effect. Further, in the case of including multiple multiple quantum well structures, the confinement factors of the multiple quantum well structures in the same optical field are within the same preset range, that is, the confinement factors of each multiple quantum well structure are maintained at the same level, so that the contribution of each multiple quantum well structure to light emission is similar. It can be understood that similar light emission contributions mean that the current injection in each multiple quantum well structure is more uniform, which helps to reduce the threshold current of the device, thereby reducing the power consumption of the device and prolonging its service life. Moreover, when the contribution of each multiple quantum well structure to light emission is similar, the distribution of carriers in each multiple quantum well structure will be more uniform, which helps to reduce the recombination loss of carriers and thus improve the overall light emission efficiency of the device.

[0046] Generally, the number of the optical confinement layers 132 is not greater than that of the active layers 120, and for example, it can be 2, 3, 4, etc. The optical confinement layers 132 are used to define the light-emitting region of the vertical cavity surface emitting laser. Specifically, the optical confinement layers 132 are located on the side of the corresponding active layers 120 away from the substrate 10 to restrict the flow of current, so that the current only flows within the light-emitting region defined by the optical confinement layers 132, thereby reducing unnecessary energy consumption, further reducing the threshold current, and increasing the current density. Moreover, the optical confinement layers 132 can also confine the optical field within the light-emitting region defined by the optical confinement layers 132, reducing the scattering and diffraction of light, thereby optimizing the divergence angle of the device and improving the beam quality. Generally, the optical confinement layers 132 are arranged at the position where the optical field intensity is the lowest, that is, at the trough of the standing wave, so that it has a small confinement factor, which helps to reduce the divergence angle of the device.

[0047] The optical confinement layer 132 can include any one of an air column type optical confinement layer, an oxidation confinement type optical confinement layer, an ion implantation type optical confinement layer, and a tunnel junction type optical confinement layer. Among them, the air column type optical confinement layer realizes the confinement of current and light through air columns. The air columns are hollow structures formed by dry etching technology, and their refractive index is lower than that of the surrounding semiconductor materials, so as to effectively confine the light within the central region. The ion implantation type optical confinement layer changes its electrical properties by implanting ions into the semiconductor material to form a high-resistance region, and the high-resistance region can restrict the flow of current, thereby indirectly restricting the light generation region.

[0048] In one embodiment, the oxidation confinement type optical confinement layer includes an unoxidized region made of AlGaAs material with a high Al component and an oxidized region made of alumina material. The oxidized region is arranged outside the unoxidized region, and the unoxidized region forms a light-emitting region for effective current injection. Among them, the semiconductor layer of the unoxidized region in the optical confinement layer 132 can be understood as an opening ( Figures 2a - 2e OA in), and the opening is used to define the light-emitting area of the vertical cavity surface emitting laser. When the current enters, the current can only flow to the active layer 120 through the opening in the optical confinement layer 132, thereby realizing the confinement of the current injection path and the optical mode field. Further, through a selective oxidation process, the AlGaAs layer with a high aluminum component can be converted into alumina to form the peripheral unoxidized region.

[0049] In one embodiment, the tunnel junction type optical confinement layer includes at least one high-doped N-type structural layer and at least one high-doped P-type structural layer. Specifically, a potential barrier is formed between the high-doped N-type structural layer and the high-doped P-type structural layer, and electrons are allowed to pass through the potential barrier through the tunnel effect, thereby realizing the lateral confinement of current. In one embodiment, the materials of the N-type structural layer and the P-type structural layer are selected as Al x Ga 1-xAs, the doping concentration of the N-type structure layer and the P-type structure layer is greater than 1e 18 cm -3 , where 0 ≤ x ≤ 1.

[0050] In one embodiment, the base layer 144 may include any one of gallium arsenide, indium phosphide, and silicon dioxide. Further, the refractive index of the base layer 144 can be made greater than or equal to twice the refractive index of the injection layer 142 by ion implantation. Further still, the material for ion implantation includes at least one of the following substances:

[0051] H+, O+, N+, Ar+.

[0052] Exemplarily, taking gallium arsenide with a refractive index of 3.3 as an example, by high-dose proton (H+) implantation (dose ≥ 1×10 17 ions / cm², energy 150 keV) combined with a controllable annealing (<400 °C) process, an amorphous porous structure can be formed in GaAs, reducing its refractive index from 3.3 to about 1.6, thereby forming a refractive index difference to form the injection layer 142.

[0053] Similarly, indium phosphide (InP) and silicon dioxide can be implanted in a similar manner. Among them, the implantation energy of indium phosphide can be between 100 keV and 1 MeV (depending on the layer thickness), and the implantation dose can be selected from 1×10 14 to 5×10 15 ions / cm². The implantation energy of silicon dioxide can be between 50 keV and 300 keV (for thinner SiO2 film layers), and the implantation dose is between 1×10 14 to 1×10 16 ions / cm².

[0054] In one embodiment, reference can be made to Figures 2a - 2e for schematic diagrams of different patterns constituting the injection layer 142. In Figures 2a - 2e , the injection layer 142 may include a plurality of strip patterns or a plurality of dot patterns. That is to say, the injection layer 142 may include a plurality of strip patterns (such as Figures 2a - 2c ), or may include a plurality of dot patterns (such as Figure 2d , Figure 2e ). Moreover, the strip patterns or dot patterns are evenly distributed in the base layer 144. Even distribution can be understood as the same spacing between each strip pattern, or the same spacing between each dot pattern. The spacing can refer to the spacing in one-dimensional or two-dimensional levels, and this application does not limit this.

[0055] Further, as shown in Figure 2cAs shown, the size of at least some of the strip patterns is different from that of the remaining strip patterns. In this embodiment, mainly the size (width) of the strip pattern in the middle is larger than the size (width) of the strip patterns on both sides. In other embodiments, it can be the opposite, or it can be gradually changed in two opposite directions. This application does not limit this. Or, as Figure 2e shown, the size of at least some of the dot patterns is different from that of the remaining dot patterns. In this embodiment, mainly based on the size (diameter) of the dot pattern in the middle, the diameter gradually decreases towards both sides. In other embodiments, the diameter in the middle can also be larger than the diameters on both sides, and the diameters on both sides are the same, or it can be gradually changed in one direction. This application does not limit this. In this way, the surface emitter with multiple OAs (oxidation apertures) can adjust the far-field divergence angle and the overall divergence angle. Further, as Figure 2a 、 Figure 2b shown, the sizes (widths) of the strip patterns are the same. Or, as Figure 2d shown, the sizes (diameters) of the dot patterns are the same. It can be understood that when the injection layer 142 is composed of other patterns, the size can also be represented through other dimensions. Those skilled in the art can make selections and adjustments according to the actual situation on this basis. This application does not make further limitations here.

[0056] In one embodiment, this application can set the whole of a partial area formed after ion implantation to be within ( Figures 2b - 2e ), or just equal to ( Figure 2a ), the range of OA, so as to achieve mode control (suppressing high-order modes) and far-field divergence angle regulation. In other embodiments, the ion implantation area can also be adjusted according to the actual situation. For example, the entire substrate 144 is ion implanted. This application does not limit this.

[0057] In some embodiments, it is defined that the multiple injection layers 142 of the grating structure 140 are planar with the surface of the grating structure 140. That is, selective surface ion implantation on the epitaxial structure (grating structure 140) can be used to form an inherently planar grating. The grating structure 140 can have a pattern including, for example, a series of lines (for example, from the top view of a vertical cavity surface emitting laser), or it can be another type of pattern.

[0058] In one embodiment, reference can be made to Figure 1 or Figure 4, in this specific embodiment, the depth of the same strip-shaped pattern is less than the width of the strip-shaped pattern; or, the depth of the same dot-shaped pattern is less than the width of the dot-shaped pattern, that is, the depth of a single pattern in the injection layer 142 needs to be less than the width of the same pattern. In some embodiments, the depth of the given injection layer 142 can be in the range from about 0.11×λ to about 0.26×λ, where λ is the wavelength of the vertical cavity surface emitting laser.

[0059] Furthermore, the depth of the strip-shaped pattern or the dot-shaped pattern is not greater than the wavelength of the surface emitting laser, and the grating period of the grating structure 140 is not greater than the wavelength of the surface emitting laser. Exemplarily, for a 940 nm wavelength (λ = 940 nm), the thickness of the injection layer 142 can be in the range from about 100 nm to about 250 nm, such as 125 nm. In some embodiments, the width of the given injection layer 142 can be equal to the pitch p of the pattern of the grating structure multiplied by 1 minus the duty cycle DC of the pattern (width = p×(1 - DC)). In some embodiments, the duty cycle DC can be in the range from about 0.4 to about 0.6, such as 0.5. As an example, for a duty cycle DC of 0.5 and a pitch p in the range from 0.20 μm to 0.45 μm, the width of the given injection layer 142 can be in the range from about 0.09×λ to about 0.23×λ. In one example, for a 940 nm wavelength (λ = 940 nm), the width of the given injection layer 142 for a duty cycle DC of 0.5 can be in the range from about 0.10 μm to about 0.23 μm. It can be understood that for other wavelengths, such as 850 nm, 1330 nm, it can be designed in this way. In some embodiments, the pitch of the pattern of the grating structure 140 can be in the range from about 0.20 μm to about 0.45 μm. Additionally or alternatively, the pitch of the pattern can be in the range from about 0.21×λ to about 0.48×λ, where λ is the wavelength of the vertical cavity surface emitting laser.

[0060] In one embodiment, it further includes a dielectric layer 150 formed on the grating structure 140; the dielectric layer 150 is a layer that at least partially insulates the top metal 160 from one or more other layers or features (e.g., the sidewalls of the trenches). Further, the dielectric layer 150 can be used to protect the grating structure 140. In some embodiments, the dielectric layer 150 can include, for example, silicon nitride (SiNX), silicon dioxide (SiO2), a polymer dielectric, or another type of insulating material. In some embodiments, a first portion of the dielectric layer 150 can be formed before forming the plurality of implanted layers 142, and a second portion of the dielectric layer 150 can be formed after forming the plurality of implanted layers 142. In some embodiments, the thickness t of the dielectric layer 150 can be in the range from about 0.92×(λ / nd) to about 1.45×(λ / nd), where λ is the wavelength of the vertical cavity surface emitting laser and nd is the refractive index of the dielectric material. More generally, the thickness T of the dielectric layer 150 can be equal to the thickness t plus or minus a value that corresponds to a multiple of the wavelength of the vertical cavity surface emitting laser divided by twice the refractive index of the dielectric material (e.g., T = t ± X×λ / (2*nd), where 0.92×(λ / nd) ≤ t ≤ 1.45×(λ / nd), and X is an integer value such as 0, 1, 2, etc.). In some embodiments, the thickness T of the dielectric layer 150 can vary by some amount (e.g., ±10 nm, ±15 nm) according to the VCSEL design. Thus, in some embodiments, the thickness of the dielectric layer 150 is within a value of about 15 nm, which is equal to the value in the range from about 0.92×(λ / nd) to about 1.45×(λ / nd) plus or minus a value equal to X×λ / (2*nd), where λ is the wavelength of the VCSEL, nd is the refractive index of the dielectric material, and X is an integer value.

[0061] In one embodiment, as Figure 4As shown, an ohmic contact metal 190 is above or below the grating structure 140 or formed in an opening of the grating structure 140. Specifically, the ohmic contact metal 190 is the top contact layer of a vertical cavity surface emitting laser, which is in electrical contact with the top mirror structure 130 through which current can flow. In some embodiments, the ohmic contact metal 190 is formed of a material optimized for contacting a p-type semiconductor. Alternatively, in some embodiments, the ohmic contact metal 190 can also be formed of a material optimized for contacting an n-type semiconductor. In some embodiments, the thickness of the ohmic contact metal 190 ranges from about 0.2 μm to about 0.8 μm, such as 0.5 μm. In some embodiments, the ohmic contact metal 190 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 vertical cavity surface emitting laser). In some embodiments, in the case of a non-circular shape, the axis of the non-circular shape can be perpendicular or parallel to the direction of a given injection layer 142.

[0062] In some embodiments, as Figure 4 shown, in some embodiments, the ohmic contact metal 190 can be in an opening in the grating structure 140. Alternatively, in some embodiments, the ohmic contact metal 190 can be below the grating structure 140. Alternatively, the ohmic contact metal 190 is above the grating structure 140 (e.g., on the base layer 144).

[0063] In one embodiment, to achieve the desired high reflectivity, a reflectivity compensation structure (not shown in the figure) can be additionally designed. The reflectivity compensation structure is configured to increase the reflectivity on the side of the vertical cavity surface emitting laser that includes the bottom mirror structure 110 (e.g., the top side of the vertical cavity surface emitting laser). In the absence of the reflectivity compensation structure, due to the required high reflectivity and the reduced interaction between the cavity mode and the optical element, the efficiency of integrating an optical element (such as a grating) in a vertical cavity surface emitting laser on top of a fully semiconductor DBR mirror is low (e.g., compared to a top-emitting vertical cavity surface emitting laser). Reducing the number of mirror pairs in the top mirror structure 130 increases the coupling of the cavity mode with such an optical element. However, reducing the number of mirror pairs in the top mirror structure 130 reduces the reflectivity on the side of the vertical cavity surface emitting laser that includes the top mirror structure. In a vertical cavity surface emitting laser, the reflectivity compensation structure is used to increase the reflectivity on the side of the vertical cavity surface emitting laser that includes the bottom mirror structure 110. Therefore, the number of mirror pairs in the bottom mirror structure 110 can be reduced, and the reflectivity compensation structure can be designed to mitigate the reduction in reflectivity caused by the reduction in the number of mirror pairs in the bottom mirror structure 110. In some embodiments, the reflectivity compensation structure can include multiple DBR pairs or another type of mirror structure. In some embodiments, the reflectivity compensation structure is formed of a dielectric material. Thus, in some embodiments, the reflectivity compensation structure includes multiple dielectric DBR pairs. For example, the reflectivity compensation structure can include multiple SiO2 / SiNx mirror pairs, multiple SiO2 / titanium dioxide (TiO2) mirror pairs, or multiple Al2O3 / TiO2 mirror pairs, among other examples. In some embodiments, the thickness of the reflectivity compensation structure can be in the 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 compensation structure is in the range from three mirror pairs to eight mirror pairs.

[0064] Figure 4 In the vertical cavity surface emitting laser, a top metal 160 can also be included. The top metal 160 is a top metal layer at the front side of the vertical cavity surface emitting laser. In some embodiments, the top metal 160 can be a layer that is in electrical contact with the ohmic contact metal 190 (e.g., through a via in the dielectric layer 150 and the top mirror structure 130). In some embodiments, the top metal 160 can be used as an anode for the vertical cavity surface emitting laser. In some embodiments, the top metal 160 can include an electroplated metal (such as gold (Au)) and / or a seed metal used in the electroplating process.

[0065] Figure 4In [the structure], the vertical cavity surface emitting laser may further include a bottom metal 170, which is a bottom metal layer at the rear side of the vertical cavity surface emitting laser. In some embodiments, the bottom metal 170 may be a layer that is in surface electrical contact with the substrate 10. In some embodiments, the top metal 160 may be used as the cathode for the vertical cavity surface emitting laser. In some embodiments, the top metal 160 may include electroplated metal (e.g., gold (Au)) and / or the seed metal used during the electroplating process.

[0066] Figure 4 In [the structure], the vertical cavity surface emitting laser may further include a proton implantation region 180, which is a region that prevents free carriers from reaching the edge of the trench and / or isolates adjacent vertical cavity surface emitting lasers from each other (e.g., if the trench does not completely surround the vertical cavity surface emitting laser). The proton implantation region 180 may include, for example, ion implanted materials, such as hydrogen / proton implanted materials or similar implanted elements, to reduce the conductivity.

[0067] Figure 4 The number, arrangement, thickness, order, symmetry, etc. of the layers shown are provided as examples. In practice, compared with the layers shown, Figure 4 the vertical cavity surface emitting laser may include additional layers, fewer layers, different layers, layers with different structures, or layers with different arrangements. For example, in some embodiments, the vertical cavity surface emitting laser may include a semiconductor layer (e.g., one or more p-type layers) above the grating structure 140 (e.g., instead of the dielectric layer 150). As another example, in some embodiments, the vertical cavity surface emitting laser may include an air interface above the grating structure 140 (e.g., instead of the dielectric layer 150 and the top metal 160). Additionally or alternatively, a set of layers (e.g., one or more layers) of the vertical cavity surface emitting laser may perform one or more functions described as being performed by another set of layers of the vertical cavity surface emitting laser, and any layer may include more than one layer.

[0068] In some embodiments, as Figure 3 shown, to form the grating structure 140, an epitaxial layer is grown (as a single step), and then a grating pattern is etched into a sacrificial layer PR above the grating structure 140 to expose portions of the grating structure 140. Then, the grating structure 140 is ion implanted to form a plurality of implanted layers 142. After the ion implantation, the sacrificial layer is removed, thereby leaving the grating structure 140 in the grating structure 140 while maintaining a substantially planar surface (e.g., compared to an etched grating).

[0069] In some embodiments, the vertical cavity surface emitting lasers fabricated in this application may be single-mode or multi-mode.

[0070] Compared with the method of preparing gratings by oxidation process, since the content of aluminum component in the same layer is fixed, the oxidation processes on the side close to the oxidation window and on the side far from the oxidation window are different. At the same time, when oxidizing the relevant layer through the oxidation window, it is difficult to determine whether the oxidation is carried out along the transverse direction of the relevant layer or along the direction perpendicular to the relevant layer, or to control the oxidation direction. As a result, the shape of the finally formed oxidation region is difficult to control, leading to inaccurate control of the grating size and affecting the final polarization modulation effect.

[0071] The embodiment of the present application also provides a VCSEL chip, which includes at least one laser array. The laser array includes a plurality of 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 sub-arrays. Based on the foregoing vertical-cavity surface-emitting lasers, the VCSEL chip of this embodiment has good performance in terms of reliability.

[0072] The embodiment of the present application also provides a light source for a lidar system, which includes at least one vertical-cavity surface-emitting laser as described above or at least one VCSEL chip as described above.

[0073] The embodiment of the present application also provides a lidar system, which includes a transmitting component and a receiving component. The transmitting component uses the light source for the lidar system as described above.

[0074] The foregoing disclosure provides illustrations and descriptions, but is not intended to be exhaustive of the embodiments or to limit the embodiments to the precise forms disclosed. Modifications and variations can be made in view of the foregoing disclosure, or can be obtained from the practice of the embodiments. In addition, any of the embodiments described herein can be combined, unless the foregoing disclosure specifically provides reasons why one or more of the embodiments may not be combined.

[0075] Even if specific combinations of features are recited 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 recited in the claims and / or disclosed in the specification. Although each of the dependent claims listed below may directly depend on only one claim, the disclosure of the various embodiments includes each dependent claim combined with every other claim in the claim set. As used herein, the phrase "at least one" in reference to a list of items refers to any combination of those items, including a single member. By way of example, "at least one of the following: a, b, or c" is intended to cover a, b, c, a-b, a-c, b-c, and a-b-c, as well as any combination with multiple identical items.

[0076] When a component or one or more components (e.g., a laser emitter or one or more laser emitters) are described or claimed (within a single claim or across multiple claims) as performing multiple operations or being configured to perform multiple operations, such language is intended to broadly cover a variety of architectures and environments. For example, unless otherwise expressly required (e.g., by using "a first component" and "a second component" or other language that differentiates components in the claims), such language is intended to cover a single component that performs or is configured to perform all of the operations, a group of components that jointly perform or are configured to perform all of the operations, a first component that performs or is configured to perform a first operation and a second component that performs or is configured to perform a second operation, or any combination of components that perform or are configured to perform the operations. For example, when a claim is in the form "one or more components are configured to: perform X; perform Y; and perform Z", the claim should be interpreted to mean "one or more components are configured to perform X; one or more (possibly different) components are configured to perform Y; and one or more (also possibly different) components are configured to perform Z".

[0077] The components, acts, or instructions used herein should not be construed as critical or essential unless expressly described as such. Additionally, as used herein, the articles "a" and "an" 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 conjunction 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." In instances where only one item is intended, the phrase "only one" or similar language is used. Additionally, as used herein, the terms "having," "including," "carrying," etc. are intended to be open-ended terms. Further, unless expressly stated otherwise, the phrase "based on" is intended to mean "at least partially based on." Additionally, as used herein, unless expressly stated otherwise (e.g., if used in combination with "any" or "only one of"), the term "or" when used in series is intended to be inclusive and may be used interchangeably with "and / or." Further, for ease of description, spatial relative terms such as "below," "lower," "above," "upper," etc. may be used herein to describe the relationship of one element or feature to another (one or more) element or (one or more) feature illustrated in the figures. Except for the orientation depicted in the figures, the spatial relative terms are intended to encompass different orientations of the device, apparatus, and / or element during use or operation. The device may be oriented otherwise (rotated 90 degrees or in other orientations), and the spatial relative descriptors used herein may be interpreted accordingly.

Claims

1. A surface-emitting laser, characterized in that, Comprising: A substrate; A bottom mirror structure, an active layer, and a top mirror structure disposed on the substrate; A grating structure disposed on the top mirror structure; the grating structure includes a base layer and an implanted layer obtained by ion implantation of a partial region of the base layer, the refractive index of the implanted layer is different from the refractive index of the base layer, and the grating structure is configured to control the output light polarization mode of the surface-emitting laser.

2. The surface-emitting laser according to claim 1, characterized in that, The base layer includes any one of gallium arsenide, indium phosphide, and silicon dioxide.

3. The surface emitting laser according to claim 1, characterized in that, The implanted layer includes a plurality of strip patterns or a plurality of dot patterns; or The strip patterns or dot patterns are uniformly distributed in the base layer.

4. The surface-emitting laser according to claim 3, wherein The sizes of at least some of the strip patterns are different from the sizes of the remaining strip patterns; or The sizes of at least some of the dot patterns are different from the sizes of the remaining dot patterns.

5. The surface-emitting laser according to claim 3, characterized in that, The sizes of each of the strip patterns are the same; or the sizes of each of the dot patterns are the same.

6. The surface-emitting laser according to claim 3, wherein The depth of the same strip pattern is less than the width of the strip pattern; or, the depth of the same dot pattern is less than the width of the dot pattern.

7. The surface emitting laser according to claim 3, characterized in that, The depth of the strip pattern or the dot pattern is not greater than the wavelength of the surface-emitting laser; or The grating period of the grating structure is not greater than the wavelength of the surface-emitting laser.

8. The surface-emitting laser according to claim 1, characterized in that, The depth of the implanted layer is between 0.11λ - 0.26λ, where λ is the wavelength of the surface-emitting laser.

9. The surface-emitting laser according to claim 1, wherein The width of the implanted layer is between approximately 0.09λ - 0.23λ, where λ is the wavelength of the surface-emitting laser.

10. The surface-emitting laser according to claim 1, characterized in that, The side of the grating structure facing away from the epitaxial structure is a plane.

11. The surface-emitting laser according to any one of claims 1-10, characterized in that, The refractive index of the base layer is greater than or equal to twice the refractive index of the implanted layer.

12. The surface-emitting laser according to any one of claims 1 to 10, characterized in that, Further comprising a dielectric layer formed on the grating structure; or Ohmic contact metal above or below the grating structure or formed in the opening of the grating structure.

13. The surface-emitting laser according to any one of claims 1 to 10, characterized in that, The material for the ion implantation includes at least one of the following substances: H+, O+, N+, Ar+.

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