semiconductor laser

Abstract

The embodiment of the present application relates to a kind of semiconductor laser, comprising: growth substrate;Resonant cavity structure is arranged on the growth substrate;Grating unit, is arranged on the side of the resonant cavity structure away from the growth substrate;The grating unit includes the low refractive index region and high refractive index region arranged alternately, and the low refractive index region is made by ion implantation to the high refractive index region.Application of the scheme of the present application can improve the surface flatness of grating, and grating unit is made nearly planarization.

Description

Technical Field

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

[0002] Semiconductor lasers, such as vertical cavity surface-emitting lasers (VCSELs), typically have random polarization directions. However, in many applications, laser output with a stable polarization direction is crucial for the entire system. Therefore, a high-contrast grating is usually fabricated on the output side of the VCSEL for polarization control.

[0003] Current gratings are typically fabricated using a deposition and etching process, which results in a non-planar surface. In conventional cases, an additional layer of material needs to be fabricated on the surface of the grating to achieve an ideal planar shape. Utility Model Content

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

[0005] In a first aspect, this application provides a semiconductor laser, comprising:

[0006] Growth substrate;

[0007] A resonant cavity structure disposed on the growth substrate;

[0008] A grating unit is disposed on the side of the resonant cavity structure opposite to the growth substrate; the grating unit includes alternating low refractive index regions and high refractive index regions, wherein the low refractive index regions are obtained by ion implantation of the high refractive index regions.

[0009] In one embodiment, the grating unit is made of any one of gallium arsenide, indium phosphide, and silicon dioxide.

[0010] In one embodiment, the ion-implanted material is any of the following substances:

[0011] H+, O+, N+, Ar+.

[0012] In one embodiment, the projection of the low refractive index region onto the surface of the resonant cavity structure is a strip-shaped structure or a dot-shaped structure.

[0013] In one embodiment, a plurality of strip-shaped structures or a plurality of dot-shaped structures are regularly distributed; or

[0014] Several strip-shaped structures or several point-shaped structures are randomly distributed; or

[0015] Several strip-shaped structures or several point-shaped structures are distributed radially.

[0016] In one embodiment, at least some of the strip structures have dimensions different from the dimensions of the remaining strip structures; or

[0017] At least some of the point structures have different dimensions than the rest.

[0018] In one embodiment, the strip structures are all the same size; or the dot structures are all the same size.

[0019] In one embodiment, the depth of the same strip structure is less than the width of the strip structure; or, the depth of the same point structure is less than the width of the point structure.

[0020] In one embodiment, the depth of the strip structure or the dot structure is not greater than the wavelength of the semiconductor laser; and / or

[0021] The grating period of the grating unit is not greater than the wavelength of the semiconductor laser.

[0022] In one embodiment, the depth of the low refractive index region is between 0.11λ and 0.26λ, where λ is the wavelength of the semiconductor laser.

[0023] In one embodiment, the width of the low refractive index region is between about 0.09λ and 0.23λ, where λ is the wavelength of the semiconductor laser.

[0024] In one embodiment, a dielectric layer formed on the grating unit is further included; and / or

[0025] Ohmic contact metal formed above or below the grating unit or in the opening of the grating unit.

[0026] In one embodiment, the side of the grating unit facing away from the resonant cavity structure is a plane.

[0027] In one embodiment, the refractive index of the high refractive index region is greater than or equal to twice the refractive index of the low refractive index region.

[0028] The aforementioned semiconductor laser, by introducing a planar grating fabricated by ion implantation, can avoid the problems of voids, protrusions, and difficulties in surface planarization caused by the surface unevenness resulting from the current mainstream deposition and etching process for fabricating gratings.

[0029] Secondly, this application provides a VCSEL chip, including at least one laser array; the laser array includes multiple semiconductor lasers as described above; the laser array is a regularly arranged array, or a randomly arranged array, or an array with multiple addressable subarrays.

[0030] 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.

[0031] Fourthly, this application provides a lidar system, including a transmitting component and a receiving component, wherein the transmitting component employs the aforementioned light source for lidar systems. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of a semiconductor laser in one embodiment of this application;

[0033] Figures 2a-2e for Figure 1 A schematic diagram showing the relative positional relationship between OA and different grating patterns in the embodiments;

[0034] Figure 3 This is a schematic diagram of the structure before fabricating the grating unit in one embodiment;

[0035] Figure 4 This is a schematic diagram of the structure of a semiconductor laser according to another embodiment of this application.

[0036] 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

[0037] 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.

[0038] 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.

[0039] 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.

[0040] Based on this, this application creatively proposes a fabrication process for planar gratings, aiming to solve the aforementioned technical problems.

[0041] Firstly, such as Figure 1 and Figure 4 As shown, this application provides a semiconductor laser, including a growth substrate 10 and a resonant cavity structure (not shown) disposed on the growth substrate 10. The resonant cavity structure may include at least a first-type mirror structure 110, an active layer 120, and a second-type mirror structure 130; the resonant cavity structure is mainly defined by the first-type mirror structure 110 and the second-type mirror structure 130. That is, the region between the first-type mirror structure 110 and the second-type mirror structure 130 is the resonant cavity. The resonant cavity is used to generate standing waves, which are waves formed by two coherent waves propagating in opposite directions along the same straight line and superimposing on each other. Specifically, when the two waves are in phase, their amplitudes are added together to form antinodes (i.e., wave crests). When the two waves are in opposite phases, their amplitudes are subtracted to form nodes (i.e., wave troughs). Therefore, the positions of the wave crests and troughs of the standing wave are fixed.

[0042] A grating unit 140 is disposed on the side of the resonant cavity structure facing away from the growth substrate 10, specifically on the second type of mirror structure 130. The grating unit 140 includes alternating low-refractive-index and high-refractive-index regions 144, wherein the alternating arrangement is parallel to the extension surface of the growth substrate 10, and the alternating arrangement means, for example, a low / high / low / high arrangement, or a high / low / high / low arrangement. The low-refractive-index regions are obtained by ion implantation of the high-refractive-index regions 144. The grating unit 140 is configured to control the output light polarization mode of the semiconductor laser. The semiconductor laser of this application can be, for example, a vertical-cavity surface-emitting laser (VCSEL). For ease of description, a VCSEL will be used as an example in the following description.

[0043] In one embodiment, the first type of reflector structure 110 may include a periodically stacked DBR structure, that is, multiple reflectors with an optical thickness of one-quarter of the lasing wavelength, the multiple reflectors being arranged alternately according to high and low refractive indices. The second type of reflector structure 130 also includes a periodically stacked DBR structure, that is, multiple reflectors with an optical thickness of one-quarter of the lasing wavelength, the multiple reflectors being arranged alternately according to high and low refractive indices. It is understood that the composition, stacking period number, etc. of the DBR structure of the first type of reflector structure 110 and the DBR structure of the second type of reflector structure 130 may be the same or different, and this embodiment is not limited thereto. The materials of the second type of reflector structure 130 and the first type of reflector structure 110 may be dielectric materials with electrical insulating properties, such as silicon nitride, silicon oxide, aluminum oxide, or titanium oxide. The materials of the second type of reflector structure 130 and the first type of reflector structure 110 may also be semiconductor materials, such as GaAs and AlGaAs.

[0044] The growth substrate 10 is made of materials including, but not limited to, GaAs, InP, and Si. The first type of reflector structure 110 and the second type of reflector structure 130 may include films with periodically varying refractive indices to achieve efficient reflection or transmission of light within a specific wavelength range. The films with periodically varying refractive indices can be composed of semiconductor materials, dielectric materials, metal-dielectric hybrid materials, etc. For example, the first type of reflector structure 110 may be an N-type semiconductor layer, and the second type of reflector structure 130 may be a P-type semiconductor layer. Alternatively, the first type of reflector structure 110 may be a P-type semiconductor layer, and the second type of reflector structure 130 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 132, which is formed in the second type of reflector structure 130 and defines the light-emitting region.

[0045] The active layer 120 may include one active region, two active regions, three active regions, 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. The emitted photons are continuously reflected in the resonant cavity defined by the first type of mirror structure 110 and the second type of mirror structure 130, and are continuously amplified during the reflection process, thereby ultimately emitting laser light at a specific wavelength with sufficient energy.

[0046] 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.

[0047] Typically, the number of photoelectric confinement layers 132 is no greater than the number of active layers 120, for example, two, three, or four. The photoelectric confinement layer 132 is used to define the light-emitting region of the vertical-cavity surface-emitting laser. Specifically, the photoelectric confinement layer 132 is located on the side of the corresponding active layer 120 away from the growth 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 132. This reduces unnecessary energy consumption, thereby reducing the threshold current and increasing the current density. Furthermore, the photoelectric confinement layer 132 can also confine the light field within the light-emitting region defined by it, reducing light scattering and diffraction, thereby optimizing the device's divergence angle and improving beam quality. Typically, the photoelectric confinement layer 132 is positioned at the location of the 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.

[0048] The photoelectric confinement layer 132 may include any one of the following: an air-pillar type photoelectric confinement layer, an oxide-confinement type photoelectric confinement layer, an ion-implanted type photoelectric confinement layer, and a tunnel junction type photoelectric confinement layer. The air-pillar type photoelectric confinement layer confines current and light through air pillars. These air pillars are hollow structures formed using dry etching technology, and their refractive index is lower than that of the surrounding semiconductor material, thus effectively confining light within 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. This high-resistivity region restricts the flow of current, thereby indirectly confining the light-generating region.

[0049] 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 132 can be understood as an opening (…). Figures 2a-2eThe openings in the photoelectric confinement layer 132 (OA) define the light-emitting region of the vertical-cavity surface-emitting laser. When current enters, it can only flow to the active layer 120 through the openings in the photoelectric confinement layer 132, 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 outer unoxidized region.

[0050] 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.

[0051] In one embodiment, the material of the high-refractive-index region 144 can be any one of gallium arsenide, indium phosphide, and silicon dioxide. Further, the refractive index of the high-refractive-index region 144 can be made greater than or equal to twice the refractive index of the low-refractive-index region 142 by ion implantation. Even further, the ion-implanted material can be any of the following substances:

[0052] H+, O+, N+, Ar+.

[0053] For example, taking gallium arsenide with a refractive index of 3.3 as an example, high-dose proton (H+) injection (dose ≥ 1 × 10⁻⁶) is used. 17 By combining controlled annealing (<400℃) with ions / cm², energy 150keV, an amorphous porous structure can be formed in GaAs, reducing its refractive index from 3.3 to about 1.6, thereby creating a refractive index difference and forming a low refractive index region 142.

[0054] Similarly, indium phosphide (InP) and silicon dioxide can be implanted in the same manner. The implantation energy for indium phosphide can range from 100 keV to 1 MeV (depending on the layer thickness), and the implantation dose can be selected as 1 × 10⁻⁶. 14 Up to 5×10 15 ions / cm². The implantation energy for silica can range from 50keV to 300keV (for thinner SiO2 films), with an implantation dose of 1×10⁻⁶. 14 Up to 1×10 16 Between ions / cm².

[0055] In one embodiment, it may be helpful to refer to Figures 2a-2e This is a schematic diagram of different patterns constituting the low refractive index region 142. Figures 2a-2e In this structure, the projection of the low-refractive-index region 142 onto the surface of the resonant cavity structure can be a strip-shaped structure or a dot-shaped structure. That is to say, multiple low-refractive-index regions 142 can form multiple strip-shaped structures (e.g., ...). Figures 2a-2c ), or it can form multiple point-like structures (such as Figure 2d , Figure 2e Furthermore, the strip-like or dot-like structures are uniformly distributed in the high-refractive-index region 144. Uniform distribution can be understood as the same spacing between each strip-like structure or the same spacing between each dot-like structure. The spacing can refer to the spacing in a one-dimensional plane or the spacing in a two-dimensional plane, and this application does not limit it in this regard.

[0056] Furthermore, such as Figure 2c As shown, at least some of the strip structures have dimensions different from the remaining strip structures. In this embodiment, the dimensions (width) of the middle strip structure are larger than the dimensions (width) of the strip structures on both sides. In other embodiments, the opposite may be true, or the dimensions may gradually change in two opposite directions. This application does not limit this. Alternatively, as... Figure 2e As shown, at least some of the dot-like structures have different dimensions than the rest. In this embodiment, the diameter of the central dot-like structure is used as a reference, and the diameter gradually decreases towards both sides. In other embodiments, the central diameter may be larger than the diameters of the two sides, and the diameters of the two sides may be the same, or the change may be gradual along one direction. This application does not limit this. In this way, a surface emitter with multiple OA (oxide pore sizes) can achieve adjustment of the far-field divergence angle and the overall divergence angle. Furthermore, as... Figure 2a , Figure 2b As shown, all the strip structures described have the same size (width). Alternatively, as... Figure 2d As shown, the dimensions (diameter) of each of the dot-like structures are the same. It can be understood that when the projection of the low-refractive-index region 142 onto the surface of the resonant cavity structure is composed of other patterns, the dimensions can also be represented by other dimensions. Those skilled in the art can select and adjust these dimensions according to the actual situation, and this application does not impose further limitations here.

[0057] In one embodiment, this application may set the entire portion of the region formed after ion implantation to be located at ( Figures 2b-2e ) or exactly equal to ( Figure 2a Within the range of OA, mode control (suppression of higher-order modes) and far-field divergence angle modulation can be achieved. In other embodiments, the ion implantation region can also be adjusted according to actual conditions, such as ion implantation of the entire layer where the grating unit 140 is located, which is not limited in this application.

[0058] In some embodiments, the plurality of low-refractive-index regions 142 defining the grating unit 140 are planar with the surface of the grating unit 140. That is, selective surface ion implantation on the resonant cavity structure (grating unit 140) can be used to form an inherently planar grating. The grating unit 140 may have a pattern including, for example, a series of lines (e.g., viewed from a top view of a vertical-cavity surface-emitting laser), or it may be another type of pattern.

[0059] In one embodiment, see [reference] Figure 1 or Figure 4 In this specific embodiment, the depth of the same strip structure is less than the width of the strip structure; or, the depth of the same dot structure is less than the width of the dot structure, that is, the depth of a single pattern in the low refractive index region 142 needs to be less than the width of the same pattern. In some embodiments, the depth of a given low refractive index region 142 can be in the range of about 0.11×λ to about 0.26×λ, where λ is the wavelength of the vertical cavity surface-emitting laser.

[0060] Furthermore, the depth of the low-refractive-index region 142 is no greater than the wavelength of the semiconductor laser, and the grating period of the grating unit 140 is no greater than the wavelength of the semiconductor laser. For example, for a wavelength of 940 nm (λ = 940 nm), the thickness of the low-refractive-index region 142 can be in the range of about 100 nm to about 250 nm, such as 125 nm. In some embodiments, the width of a given low-refractive-index region 142 can be equal to the spacing p of the grating unit pattern 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 of about 0.4 to about 0.6, such as 0.5. As an example, for a duty cycle DC of 0.5 and a spacing p in the range of 0.20 μm to 0.45 μm, the width of a given low-refractive-index region 142 can be in the range of about 0.09 × λ to about 0.23 × λ. In one example, for a wavelength of 940 nm (λ = 940 nm), the width of a given low-refractive-index region 142 for a duty cycle DC of 0.5 can range from about 0.10 μm to about 0.23 μm. It is understood that for other wavelengths, such as 850 nm and 1330 nm, this can be designed in the same manner. In some embodiments, the spacing of the pattern of the grating unit 140 can range from about 0.20 μm to about 0.45 μm. Additionally or alternatively, the spacing of the pattern can range from about 0.21 × λ to about 0.48 × λ, where λ is the wavelength of the vertical-cavity surface-emitting laser.

[0061] In one embodiment, see [reference] Figure 4The system also includes a dielectric layer 150 formed on the grating unit 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., sidewalls of trenches). Further, the dielectric layer 150 may be used to protect the grating unit 140. In some embodiments, the dielectric layer 150 may 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 may be formed before the formation of the plurality of low-refractive-index regions 142, and a second portion of the dielectric layer 150 may be formed after the formation of the plurality of low-refractive-index regions 142. In some embodiments, the thickness t of the dielectric layer 150 may 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 corresponding to the wavelength of the vertical-cavity surface-emitting laser divided by a multiple of 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 depending on the VCSEL design (e.g., ±10 nm, ±15 nm). Thus, in some embodiments, the thickness of the dielectric layer 150 is in the range of about 15 nm, which is equal to a value in the range of 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.

[0062] In one embodiment, such as Figure 4As shown, an ohmic contact metal 190 is formed above or below the grating unit 140 or in an opening of the grating unit 140. Specifically, the ohmic contact metal 190 is the top contact layer of the vertical-cavity surface-emitting laser (VCSEL) that is in electrical contact with the second-type mirror structure 130 through which current can flow. In some embodiments, the ohmic contact metal 190 is formed of a material optimized for contacting p-type semiconductors. Alternatively, in some embodiments, the ohmic contact metal 190 may also be formed of a material optimized for contacting n-type semiconductors. In some embodiments, the thickness of the ohmic contact metal 190 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 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 VCSEL). In some embodiments, in the case of a non-circular shape, the axis of the non-circular shape may be perpendicular to or parallel to the direction of a given low-refractive-index region 142.

[0063] In some implementations, such as Figure 4 As shown, in some embodiments, the ohmic contact metal 190 may be located within an opening in the grating unit 140. Alternatively, in some embodiments, the ohmic contact metal 190 may be located below the grating unit 140. Alternatively, the ohmic contact metal 190 may be located above the grating unit 140.

[0064] 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 vertical-cavity surface-emitting laser (VCSEL) including the first-type mirror structure 110 (e.g., the top side of the VCSEL). Without the reflectivity supplement structure, the efficiency of integrating optical elements (such as gratings) in a top-emitting VCSEL with an all-semiconductor DBR mirror is lower (e.g., compared to a top-emitting VCSEL) due to the required high reflectivity and reduced interaction between the cavity mode and optical elements. Reducing the number of mirror pairs in the second-type mirror structure 130 increases the coupling between the cavity mode and such optical elements. However, reducing the number of mirror pairs in the second-type mirror structure 130 reduces the reflectivity on the side of the VCSEL including the second-type mirror structure. In a VCSEL, the reflectivity supplement structure is used to increase the reflectivity on the side of the VCSEL including the first-type mirror structure 110. Therefore, the number of mirror pairs in the first-type mirror structure 110 can be reduced, and the reflectivity supplementation structure can be designed to mitigate the decrease in reflectivity caused by the reduction in the number of mirror pairs in the first-type mirror structure 110. 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 be in the range of 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 is in the range of three to eight mirror pairs.

[0065] Figure 4 The vertical-cavity surface-emitting laser (VCSEL) may further include a top metal 160, which is a top metal layer at the front side of the CCSEL. In some embodiments, the top metal 160 may be a layer electrically contacting an ohmic contact metal 190 (e.g., through a via in the dielectric layer 150 and the type-2 mirror structure 130). In some embodiments, the top metal 160 may serve as an anode for the CCSEL. In some embodiments, the top metal 160 may include an electroplated metal (e.g., gold (Au)) and / or a seed metal used in the electroplating process.

[0066] Figure 4The vertical-cavity surface-emitting laser (VCSEL) may further include a bottom metal 170, which is a bottom metal layer located on the rear side of the CCSEL. In some embodiments, the bottom metal 170 may be a layer that is electrically in contact with the entire surface of the growth substrate 10. In some embodiments, the top metal 160 may be used as a cathode for the CCSEL. In some embodiments, the top metal 160 may include electroplated metal (e.g., gold (Au)) and / or seed metal used in the electroplating process.

[0067] Figure 4 In this design, the vertical-cavity surface-emitting laser (VCSEL) may further include a proton injection region 180, which is a region that prevents free carriers from reaching the edge of the trench and / or isolates adjacent VCSELs from each other (e.g., if the trench does not completely surround the VCSEL). The proton injection region 180 may include, for example, an ion implantation material, such as a hydrogen / proton implantation material or a similar implantation element, to reduce conductivity.

[0068] Figure 4 The number, arrangement, thickness, order, and symmetry of the layers are provided as examples. In practice, with... Figure 4 Compared to the layers shown, a vertical-cavity surface-emitting laser (VCSEL) can include additional layers, fewer layers, different layers, layers with different structures, or layers with different arrangements. For example, in some embodiments, a VCSEL can include a semiconductor layer (e.g., one or more p-type layers) above grating unit 140 (e.g., instead of dielectric layer 150). As another example, in some embodiments, a VCSEL can include an air interface (e.g., instead of dielectric layer 150 and top metal 160) above grating unit 140. Additionally or alternatively, a set of layers (e.g., one or more layers) of a VCSEL can perform one or more functions described as being performed by another set of layers of a VCSEL, and any layer can include more than one layer.

[0069] In some implementations, such as Figure 3 As shown, to form the grating unit 140, an epitaxial layer is grown (as a single step), and then the grating pattern is etched into a sacrificial layer PR over the high-refractive-index region 144 to expose a portion of the high-refractive-index region 144. The high-refractive-index region 144 is then ion-implanted to form a plurality of low-refractive-index regions 142. After ion implantation, the sacrificial layer is removed, thereby leaving the low-refractive-index regions 142 within the high-refractive-index region 144 while maintaining a substantially planar surface (e.g., compared to the etched grating).

[0070] In some implementations, the vertical cavity surface-emitting laser fabricated in this application can be single-mode or multi-mode.

[0071] Compared to fabricating gratings using an oxidation process, the oxidation process differs between the side near the oxidation window and the side farther away, because the aluminum content in the same layer is fixed. Furthermore, controlling whether the oxidation occurs transversely or perpendicularly to the relevant layer, or even the direction of oxidation itself, is quite difficult. This makes it hard to control the shape of the final oxide region, resulting in inaccurate control of the grating size and affecting the final polarization modulation effect.

[0072] This application also provides a VCSEL chip, which includes at least one laser array. The laser array includes multiple semiconductor 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 vertical-cavity surface-emitting laser, the VCSEL chip of this embodiment exhibits good reliability.

[0073] This application also 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.

[0074] 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.

[0075] 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.

[0076] 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.

[0077] 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.”

[0078] 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 semiconductor laser, characterized in that, include: Growth substrate; A resonant cavity structure disposed on the growth substrate; A grating unit is disposed on the side of the resonant cavity structure opposite to the growth substrate; the grating unit includes alternating low refractive index regions and high refractive index regions, wherein the low refractive index regions are obtained by ion implantation of the high refractive index regions.

2. The semiconductor laser according to claim 1, characterized in that, The grating unit is made of any one of gallium arsenide, indium phosphide, or silicon dioxide.

3. The semiconductor laser according to claim 2, characterized in that, The ion implantation material is any of the following substances: H+, O+, N+, Ar+.

4. The semiconductor laser according to claim 1, characterized in that, The projection of the low refractive index region onto the surface of the resonant cavity structure is a strip-shaped structure or a dot-shaped structure.

5. The semiconductor laser according to claim 4, characterized in that, Several strip-like structures or several point-like structures are regularly distributed; or Several strip-shaped structures or several point-shaped structures are randomly distributed; or Several strip-shaped structures or several point-shaped structures are distributed radially.

6. The semiconductor laser according to claim 4, characterized in that, At least some of the strip structures have dimensions different from the dimensions of the rest of the strip structures; or At least some of the point structures have different dimensions than the rest.

7. The semiconductor laser according to claim 4, characterized in that, All strip structures have the same size; or all point structures have the same size.

8. The semiconductor laser according to claim 4, characterized in that, The depth of the same strip structure is less than the width of the same strip structure; or, the depth of the same point structure is less than the width of the same point structure.

9. The semiconductor laser according to claim 4, characterized in that, The depth of the strip structure or the dot structure is not greater than the wavelength of the semiconductor laser; and / or The grating period of the grating unit is not greater than the wavelength of the semiconductor laser.

10. The semiconductor laser according to claim 1, characterized in that, The depth of the low refractive index region is between 0.11λ and 0.26λ, where λ is the wavelength of the semiconductor laser.

11. The semiconductor laser according to claim 1, characterized in that, The width of the low refractive index region is between approximately 0.09λ and 0.23λ, where λ is the wavelength of the semiconductor laser.

12. The semiconductor laser according to claim 1, characterized in that, The side of the grating unit that faces away from the resonant cavity structure is a plane.

13. The semiconductor laser according to any one of claims 1-12, characterized in that, The refractive index of the high refractive index region is greater than or equal to twice the refractive index of the low refractive index region.

14. The semiconductor laser according to any one of claims 1-10, characterized in that, It also includes a dielectric layer formed on the grating unit; and / or Ohmic contact metal formed above or below the grating unit or in the opening of the grating unit.

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