Method for manufacturing a semiconductor laser device, semiconductor laser device and apparatus

Abstract

Embodiments of the present application provide a preparation method of a semiconductor laser device, a semiconductor laser device and equipment, and relate to the technical field of optical chips. The semiconductor laser device includes a plurality of light emitting points. Each light emitting point includes a grating layer. The plurality of light emitting points are divided into multiple groups, and the grating layers of the light emitting points of different groups have the same extension direction but different etching depths, so that the light emitting points of each group emit different polarization state lasers. The preparation method includes: forming a grating mask pattern covering all light emitting point regions and having the same extension direction; and based on the grating mask pattern, through k kinds of etchants and t times of etching processes, different grating etching depths are formed for N groups of light emitting points simultaneously. The present application can realize multiple different polarization state emitted light on the same chip in a low-cost, high-integration and high-efficiency manner, and by optimizing the types of etchants and the number of etching times, the process steps can be significantly reduced.

Description

Technical Field

[0001] This invention relates to the field of optical chip technology, and more specifically, to a method for fabricating a semiconductor laser device, a semiconductor laser device, and an apparatus. Background Technology

[0002] Vertical-cavity surface-emitting lasers (VCSELs) have been widely used in 3D imaging, high-precision sensing, and other fields due to their small size, low power consumption, and ease of two-dimensional integration. In applications such as structured light coding, polarization imaging, and multi-channel optical communication, it is often necessary for the light source to provide output light with multiple different polarization states to obtain richer object information or achieve signal multiplexing. For example, in polarized structured light 3D reconstruction, alternating the use of illumination light with different polarization states can effectively suppress specular reflection and improve reconstruction accuracy; in polarization-multiplexed optical communication, light with different polarization states can carry independent information channels. These applications require the light source chip itself to directly provide multiple polarization states of output, rather than relying on external, bulky optical components.

[0003] However, when integrating multiple light-emitting regions with different polarization states onto a single light source, traditional methods often require fabricating multiple sets of gratings with different orientations on the same epitaxial structure. This process is complex, alignment is difficult, and consistency is hard to guarantee. When using low-cost techniques such as nanoimprint lithography to fabricate gratings, due to process limitations, all grating lines can usually only extend in the same direction, making it impossible to fabricate grating structures with multiple polarization characteristics in the same process step. Using external optical components increases system size and cost, introduces additional optical losses, and makes it difficult to achieve perfect spot overlap. Therefore, there is a lack of a light source structure that can realize multiple light-emitting regions with different polarization states on a single chip in a low-cost, highly integrated manner. Summary of the Invention

[0004] The present invention aims to provide a method for fabricating a semiconductor laser device, a semiconductor laser device and equipment, which can solve the problem in related technologies that it is difficult to realize multiple different polarization states of emitted light on the same chip at low cost and with high integration.

[0005] The embodiments of the present invention can be implemented as follows: In a first aspect, the present invention provides a method for fabricating a semiconductor laser device, which is used to fabricate a semiconductor laser device integrating multiple light-emitting points, comprising the following steps: An epitaxial structure is provided, wherein the surface of the epitaxial structure has a grating layer; A grating mask pattern covering all light-emitting point areas and having the same extension direction is formed on the grating layer; Based on the grating mask pattern, different grating etching depths are formed simultaneously for N groups of light-emitting points using k etchants and t etching processes, thereby enabling different groups of light-emitting points to emit lasers with different polarization states; each etchant corresponds to a different etching rate; Where k and t are both positive integers, and when k ≠ 1, t is equal to or greater than logt. k The smallest positive integer N; when k = 1, t is greater than or equal to N.

[0006] In an optional implementation, when k=1, the step of synchronously forming different grating etching depths corresponding to N groups of light-emitting points specifically includes: A protective layer is formed in the grating layer region corresponding to the other groups of light-emitting points besides the target light-emitting point; Using the grating mask pattern as a mask, the grating layer of at least the target light-emitting point is etched to increase the etching depth of the grating layer of the target light-emitting point, while the etching depth of the grating layer of other groups of light-emitting points remains unchanged, and the number of the target light-emitting points is at least one group; The protective layers of the other groups of light-emitting points are removed in sequence. After the protective layers are removed, the grating mask pattern is used as a mask to perform synchronous etching on the grating layer of the light-emitting points without protective layers at least once, so that the grating depth of each group of light-emitting points without protective layers increases synchronously, and the depth of the light-emitting points without protective layers remains unchanged. Different grating etching depths are formed between different groups of light-emitting points.

[0007] In an optional implementation, before forming a protective layer on all other groups of light-emitting points besides the first group, the method further includes: Using the grating mask pattern as a mask, the grating layer of all light-emitting points is synchronously initially etched to form an initial etching depth; the initial etching depth is less than or equal to the minimum value of the grating etching depth.

[0008] In an optional implementation, when k≠1, the step of synchronously forming different grating etching depths corresponding to N sets of light-emitting points includes: When k equals N, t equals 1. Through a single etching process, different types of etchants are applied to different groups of light-emitting point regions. By utilizing different etchants corresponding to different etching rates, N different etching depths are formed in the grating layers of different groups of light-emitting points within the same etching time.

[0009] In an optional implementation, when k≠1, the step of synchronously forming different grating etching depths corresponding to N sets of light-emitting points includes: When k is less than N, t is greater than or equal to logkN. Through t etching processes, different etchants or protective layers are selectively applied to the grating layer of different groups of light-emitting points in each etching process, so that the cumulative etching depth of each group of light-emitting points forms N different combination values, thereby distinguishing N different etching depths with less than or equal to N etching processes.

[0010] In a second aspect, the present invention provides a semiconductor laser device, manufactured by the method for preparing a semiconductor laser device as described in any of the foregoing embodiments, comprising: Multiple light-emitting points, each of which includes a grating layer; The multiple light-emitting points are divided into multiple groups, and the grating layers of the light-emitting points in different groups have the same extension direction and different etching depths; The etching depth of the light-emitting points in different groups corresponds to different relative dichroisms, so that the light-emitting points in each group emit lasers with different polarization states.

[0011] In an optional implementation, in one of the multiple groups of light-emitting points, the multiple light-emitting points are electrically connected to each other, and the light-emitting points in different groups are configured to be energized simultaneously or independently.

[0012] In an optional embodiment, a PIN photodiode is further provided in the corresponding epitaxial structure of each light-emitting point for monitoring the output power of the corresponding light-emitting point.

[0013] In an optional implementation, the light-emitting points of different groups are arranged alternately so that when different groups of light-emitting points emit light, the light spots emitted by each group roughly overlap in space.

[0014] Thirdly, the present invention provides an apparatus comprising a semiconductor laser device as described in any of the foregoing embodiments.

[0015] The beneficial effects of the semiconductor laser device fabrication method, semiconductor laser device, and equipment provided in the embodiments of the present invention include: The semiconductor laser device fabrication method of this invention utilizes gratings with different groups of emitting points having the same extension direction but different etching depths. By leveraging the characteristic that the dichroism of the grating changes with depth, multiple different polarization states can be obtained simply by controlling the etching depth parameter, eliminating the need to fabricate gratings with different orientations. In this way, while maintaining grating orientation consistency, multiple polarization states can be achieved by controlling only the etching depth process parameter. This allows all grating patterns to be fabricated in a single photolithography process, avoiding the multiple photolithography alignment problems caused by fabricating multiple sets of gratings with different orientations in traditional methods. This significantly simplifies the process flow, reduces manufacturing costs, and improves device integration and consistency. Attached Figure Description

[0016] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the semiconductor laser device provided in this embodiment; Figure 2 This diagram illustrates the relationship between the etching depth of a grating and the relative dichroism of a laser, assuming that the grating period, duty cycle, and orientation are all the same.

[0018] Icons: 100 - Semiconductor laser device; 10 - Light emission point; 11 - First group of light emission points; 12 - Second group of light emission points; 21 - First pad; 22 - Second pad. Detailed Implementation

[0019] In related technologies, to achieve multi-polarization state output from a surface light source, the following approaches are typically adopted: First, multiple sets of gratings with different extension directions are fabricated on the same chip to obtain output light with different polarization states; second, external optical elements are used to convert or select light with a single polarization state. However, these approaches have significant shortcomings in practical applications. For the former, fabricating multiple sets of gratings with different directions often requires multiple photolithography alignment processes, which are complex and make it difficult to guarantee the alignment accuracy and consistency of different grating regions. Especially when using low-cost technologies such as nanoimprint lithography to fabricate gratings, process limitations mean that all grating lines can only extend in the same direction, making it impossible to fabricate grating structures with multiple polarization characteristics in the same process step. For the latter, introducing external optical elements increases the system size and cost, introduces additional optical losses, and makes it difficult to ensure that the light spots with multiple polarization states completely overlap in space, affecting the sharing of subsequent optical systems and imaging accuracy.

[0020] To address the aforementioned problems, this invention provides a semiconductor laser device and its fabrication method, which can achieve multiple polarization states by controlling only the etching depth process parameter while maintaining grating orientation consistency. This allows all grating patterns to be fabricated in a single photolithography process, avoiding the difficulties of multiple photolithography alignments, significantly simplifying the process flow and reducing manufacturing costs.

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0022] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0023] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0024] In the description of this invention, it should be noted that if terms such as "upper," "lower," "inner," or "outer" are used to indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship in which the product of this invention is usually placed, they are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0025] Furthermore, the terms "first" and "second" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0026] It should be noted that, where there is no conflict, the features in the embodiments of the present invention can be combined with each other.

[0027] The following detailed description, through embodiments and in conjunction with the accompanying drawings, details the overall structure, working principle, and technical effects of the semiconductor laser device provided by the present invention, as well as the detailed steps, implementation principles, and technical effects of the supporting preparation method.

[0028] Please refer to Figure 1 The semiconductor laser device 100 provided in this embodiment of the invention can be applied to scenarios requiring multi-polarization illumination, such as 3D imaging, high-precision sensing, structured light coding, polarization optical detection, and other fields.

[0029] This semiconductor laser device 100 includes a plurality of light-emitting points 10. Each light-emitting point 10 includes a grating layer. The plurality of light-emitting points 10 are divided into multiple groups, and the grating layers of the light-emitting points in different groups have the same extension direction but different etching depths. The etching depths of the light-emitting points in different groups correspond to different relative dichroisms, so that the light-emitting points in each group emit lasers with different polarization states.

[0030] As a specific embodiment of the present invention, at least two groups of light-emitting points have different etching depths, so that the light-emitting points have different relative dichroisms.

[0031] As a specific embodiment of the present invention, two sets of light-emitting points are used as an example for explanation: the plurality of light-emitting points 10 include a first set of light-emitting points 11 and a second set of light-emitting points 12. The grating layer of the first set of light-emitting points 11 has a first grating pattern, and the grating layer of the second set of light-emitting points 12 has a second grating pattern. The first grating pattern and the second grating pattern have the same extension direction. Furthermore, the etching depth of the first grating pattern is different from the etching depth of the second grating pattern.

[0032] It is understood that the present invention is not limited to two groups, but can be extended to three, four or even more groups, with the grating depth of each group increasing sequentially, thereby obtaining a variety of different polarization states.

[0033] By setting gratings with different groups of emitting points 10 to have the same extension direction but different etching depths, the physical property of the grating's dichroism changing with depth can be utilized. This allows different groups of emitting points 10 to emit different polarization states without changing the grating orientation, simply by controlling the etching depth process parameter. For example, taking two groups as an example, one group emits TE (transverse electric mode) polarized light, and the other group emits TM (transverse magnetic mode) polarized laser light. Therefore, all grating patterns can be fabricated in a single photolithography process, avoiding the multiple photolithography alignment problems caused by fabricating two sets of gratings with different orientations in traditional solutions. This significantly simplifies the process flow, reduces manufacturing costs, and improves device integration and consistency.

[0034] The principle behind the generation of different polarization states by grating depth differences is understandable: in high-contrast gratings (HCGs) or subwavelength gratings, the etching depth of the grating directly determines the effective refractive index of the waveguide layer and the light loss in the resonant cavity. Specifically, for shallowly etched gratings: the loss for TM polarization is typically higher, while the loss for TE polarization is lower, and the laser tends to lase the TE mode. For deeply etched gratings: when the depth reaches a certain threshold, the loss of the TE mode increases sharply, while the loss of the TM mode relatively decreases, at which point the laser tends to lase the TM mode. In other words, by changing the grating etching depth, the balance point between the reflectivity and loss of the grating layer for the two polarization states is altered. For three or more groups, multiple different depth values ​​can be set, allowing each group to operate in different polarization mode regions, thereby obtaining a variety of different polarization states.

[0035] The basic structure of each emitting point 10 (such as the epitaxial layer, active region, upper and lower DBR (distributed Bragg reflector) mirrors, etc.) can adopt the conventional vertical-cavity surface-emitting laser (VCSEL) structure design in this field. The grating layer is usually located on the top layer of the output port and is used to control and select the polarization state of the emitted light. The grating layer can be silicon nitride, silicon oxide, or semiconductor materials (such as GaAs (gallium arsenide), InP (indium phosphide)).

[0036] The extension direction of the grating refers to the length direction of the grating lines (ridges or grooves). In this invention, the grating lines of all light-emitting points 10 are parallel to each other, which allows the grating pattern on the entire wafer to be completed in a single photolithography step. Different groups of grating patterns can be set to the same period and duty cycle as needed, or they can be different. However, to highlight the effect of depth difference on polarization state control and simplify the design, it is preferable that all groups have the same period and duty cycle. The grating period is usually designed in the subwavelength range, for example, between 100 nm and 500 nm. The specific value needs to be designed through simulation based on the target wavelength and material system.

[0037] It should be noted that the number of each group of light-emitting points 10 can be arbitrary, for example, each group can occupy a certain proportion. The groups of light-emitting points 10 can be arranged arbitrarily on the chip, but in order to achieve a better light spot overlap effect, they can be arranged alternately.

[0038] Furthermore, in this embodiment of the invention, for a scheme with two sets of light-emitting points, the difference between the etching depth of the first grating pattern and the etching depth of the second grating pattern is at least 10 nm. By controlling the etching depth difference to be at least 10 nm, it can be ensured that the loss difference of the two sets of gratings for TE / TM polarization produces a quantifiable distinction, thereby outputting different polarization states. For multiple schemes, the depth difference between adjacent depth values ​​of light-emitting point groups is also at least 10 nm to ensure that adjacent groups have distinguishable polarization states.

[0039] For the principle behind the different polarization states resulting from etching depth differences, please refer to [link / reference]. Figure 2 It is understandable that, in order for the two sets of emitting points 10 to emit two different polarized lights, the values ​​of the two depths must be located on either side of the critical point of polarization conversion. For example, assuming the grating period and duty cycle are fixed, as the etching depth increases, the polarization state of the emitting point 10 will switch from stable TE polarization to stable TM polarization. There is a transition region in this switching process. The etching depth of the first set of emitting points 11... The etching depth of the second group of light-emitting points 12 should be designed in the TE mode region. It should be designed in the TM mode region. The difference between the two ( The depth is large enough to span the transition region. It is understood that in this embodiment, the difference between the etching depth of the first grating pattern and the etching depth of the second grating pattern is 10 nm, which is the minimum difference between the two sets of emitting points 10 that can emit two different polarizations. For schemes with multiple sets of emitting points, multiple depth values ​​can be selected, each located in a different polarization mode region. For example, the first set could be in the TE stable region, the second set in the transition region near the TE side, the third set in the transition region near the TM side, and the fourth set in the TM stable region, etc., thereby obtaining multiple polarization states of different degrees.

[0040] Furthermore, in this embodiment, the difference between the etching depth of the first grating pattern and the etching depth of the second grating pattern is at least 50 nm, so that the two polarization states have a significant difference. It is understood that when the depth difference is greater than or equal to 50 nm, this difference in polarization states is more significant, and high-purity light with two distinct polarizations can be obtained.

[0041] In practical product design, the specific depth difference can be optimized using simulation methods such as Rigorous Coupled-Wave Analysis (RCWA), selecting two depth values ​​corresponding to the TE mode stable region and the TM mode stable region, respectively. For example, for a specific wavelength and period, simulations show that the laser emits the TE mode at an etching depth of 80 nm and the TM mode at a depth of 150 nm; therefore, a depth difference of 70 nm is an optimal value. In other embodiments, the depth difference can also be 30 nm, 100 nm, or 200 nm, as long as it ensures that the two sets of devices emit the required polarization states.

[0042] In this embodiment of the invention, in one of the multiple groups of light-emitting points, the multiple light-emitting points are electrically connected to each other, and the light-emitting points in different groups are configured to be energized simultaneously or independently. Taking two groups as an example: the light-emitting points 11 in the first group are electrically connected, and the light-emitting points 12 in the second group are electrically connected; the light-emitting points 11 in the first group and the light-emitting points 12 in the second group are configured to be energized simultaneously or independently. Optionally, in the same group of light-emitting points, the multiple light-emitting points can be connected in series or in parallel.

[0043] This electrical connection method offers flexible operating modes. Specifically, it can be achieved by designing independent P-type or N-type electrode pads on the chip. For example, the anode of the first group of light-emitting points 11 can be connected to the first pad 21 via a metal lead, and the anodes of all the light-emitting points 10 in the second group can be connected to the second pad 22. The cathodes of all the light-emitting points 10 can be shared. For schemes with multiple groups of light-emitting points, a corresponding number of independent pads can be set to control each group of light-emitting points separately.

[0044] In this configuration, when both pads are powered on simultaneously, shorting the first pad 21 and the second pad 22 or applying a driving current simultaneously will cause both sets of light-emitting points 10 to emit light simultaneously, and the surface light source will output light mixed with two polarization states. This is suitable for applications that require simultaneous acquisition of information from two polarization channels. For schemes with multiple sets of light-emitting points, simultaneous power-on can output light mixed with multiple polarization states.

[0045] When independently powered, the on / off state and current magnitude of the first pad 21 and the second pad 22 are controlled separately by the drive circuit. When only the first pad 21 is powered, the light source outputs laser light with the first polarization state; when only the second pad 22 is powered, it outputs laser light with the second polarization state. This enables rapid switching of polarization states, suitable for time-division multiplexed polarization imaging or structured light coding systems. For schemes with multiple light-emitting points, each group of light-emitting points can be controlled independently to achieve arbitrary switching or combination of multiple polarization states.

[0046] In this embodiment of the invention, a PIN photodiode is also provided in the corresponding epitaxial structure of each light-emitting point 10 for monitoring the output power of the corresponding light-emitting point 10.

[0047] Specifically, PIN photodiodes can be integrated around or below each light-emitting point 10, sharing a portion of the epitaxial layer with the VCSEL. Their working principle is that when a laser beam is emitted from a light-emitting point 10, a small amount of light is absorbed by the PIN photodiode, generating a photocurrent. The magnitude of the photocurrent is proportional to the output power. By monitoring this photocurrent, real-time monitoring and closed-loop control of the output power of each light-emitting point 10 can be achieved. Since the two sets of light-emitting points 10 emit lasers with different polarization states, their transmittance in the subsequent optical system may be inconsistent. By monitoring the PIN photodiodes, the drive current of the two sets of devices can be adjusted separately, ensuring that the light intensity after passing through the optical system remains consistent, thereby guaranteeing the stability and reliability of the system performance.

[0048] In this embodiment of the invention, different groups of light-emitting points are arranged alternately so that when different groups emit light, the emitted light spots of each group approximately overlap in space. Taking two groups as an example: the first group of light-emitting points 11 and the second group of light-emitting points 12 are arranged alternately so that the light spots emitted by the first group of light-emitting points 11 and the light spots emitted by the second group of light-emitting points 12 overlap in space. Specifically, the first group of light-emitting points 11 and the second group of light-emitting points 12 are arranged at row intervals and / or at column intervals.

[0049] For example, in this embodiment, the VCSEL array is designed with a row-interval pattern, where the light-emitting points 10 in odd-numbered rows form the first group and the light-emitting points 10 in even-numbered rows form the second group; or it is arranged with column-intervals, where the light-emitting points 10 in odd-numbered columns form the first group and the light-emitting points 10 in even-numbered columns form the second group; or it is arranged with both row and column intervals simultaneously, forming a denser alternating arrangement. This dense alternating arrangement allows the two groups of light-emitting points 10 to fully interweave in space. Since the light-emitting areas of the two groups of light spots almost completely overlap macroscopically, when they pass through subsequent optical systems such as lens groups, they can share a set of optical elements, and the positions of the light spots formed on the target plane are basically consistent, without the need for complex optical path correction. In other embodiments, random mixed arrangement or other regular arrangements that can guarantee spatial overlap can also be used.

[0050] Specifically, in this embodiment of the invention, the semiconductor laser device 100 is a vertical-cavity surface-emitting laser (VCSEL) array. VCSEL arrays have advantages such as easy two-dimensional integration, good beam quality, high modulation rate, and low cost, making them an ideal choice for realizing high-power, high-density surface light sources. Applying the dual-polarization grating structure of this invention to a VCSEL array can fully leverage the advantages of both, resulting in the fabrication of a high-performance multi-polarization state light source chip.

[0051] In this embodiment of the invention, the grating patterns of different groups of light-emitting points have the same grating period and the same duty cycle.

[0052] Period and duty cycle are key parameters determining the optical properties of a grating. Keeping them identical means that the polarization state of both gratings is controlled by only one variable: depth. This greatly simplifies the complexity of design and simulation, and allows the fabrication process to focus solely on depth control without worrying about the impact of period or duty cycle deviations on polarization performance. Theory and simulations show that, with appropriate period and duty cycle, grating depth is one of the most sensitive and effective parameters for controlling the polarization state.

[0053] The working principle and process of the semiconductor laser device 100 provided in this embodiment of the invention are as follows: Taking two sets of light-emitting points as an example, when a driving current is applied to the first set of light-emitting points 11, the current is injected into the active region to generate light radiation. The light oscillates back and forth in the resonant cavity, and its polarization state is affected by the grating layer. Since the etching depth of the first set of gratings is shallow (assuming it is h1), its loss on the TE polarization mode is small, while its loss on the TM polarization mode is large. Therefore, the laser preferentially emits TE polarized light. When a driving current is applied to the second set of light-emitting points 12, since the etching depth of the second set of gratings is deep (assuming it is h2), its loss relationship for TE and TM polarization is reversed. The loss of the TE mode increases, and the loss of the TM mode decreases. Therefore, the laser preferentially emits TM polarized light. By controlling the on and off of the two sets of devices, single polarized light output or mixed polarized light output can be achieved. Since the two sets of devices are arranged alternately in space, the illumination spots formed by their emitted beams after passing through the subsequent optical system are highly overlapping in space. For the scheme with multiple sets of light-emitting points, the principle is similar: each set of gratings has a different depth and operates in a different polarization loss state, thereby outputting its corresponding polarization state.

[0054] In summary, the semiconductor laser device 100 provided in this embodiment of the invention achieves low-cost, high-integration output of lasers with multiple polarization states on a single chip by setting multiple sets of gratings with the same direction but different etching depths. This structure simplifies the manufacturing process, reduces costs, and achieves beam spot overlap through alternating arrangement, facilitating system integration. Independent electronic control and integrated PIN diodes further enhance the flexibility and reliability of the light source.

[0055] This invention also provides a method for fabricating a semiconductor laser device 100, which is used to fabricate a semiconductor laser device 100 integrating multiple light-emitting points, specifically including the following steps: s1: Provide an epitaxial structure, the surface of which has a grating layer; s2: Form a grating mask pattern on the grating layer that covers all light-emitting point areas and has the same extension direction; s3: Based on the grating mask pattern, different grating etching depths are formed simultaneously for N groups of light-emitting points through k types of etchants and t etching processes, so that different groups of light-emitting points emit lasers with different polarization states; each etchant corresponds to a different etching rate.

[0056] Where k and t are both positive integers, and when k ≠ 1, t is equal to or greater than logt. k The smallest positive integer N; when k = 1, t is greater than or equal to N.

[0057] The core of this preparation method lies in utilizing multiple etchants (k types) and / or multiple etching processes (t times) to form N different grating etching depths among N groups of light-emitting points with the fewest etching steps. Different types of etchants have different etching rates on the grating layer material; therefore, within the same etching time, regions with different etchants will produce different etching depths. When the number of etchant types k equals 1, N depths can only be distinguished through multiple etching steps (t times) combined with selective protection, requiring at least N etching steps (t ≥ N). When the number of etchant types k is greater than 1, the diversity of etchants can be utilized to achieve different depths through one or more etching steps (t ≥ log0). k N) can achieve N different depths, thereby reducing the number of etching operations and improving efficiency.

[0058] It is understood that the above "synchronously" means that in the same etching process, all unprotected areas or areas with a specific etchant are etched at the same time to ensure process consistency.

[0059] Furthermore, when k=1, the specific steps of simultaneously forming different grating etching depths corresponding to N sets of light-emitting points include: S3.1: A protective layer is formed in the grating layer region corresponding to the other groups of light-emitting points besides the target light-emitting point; S3.2: Using the grating mask pattern as a mask, etch the grating layer of at least the target light-emitting point to increase the etching depth of the grating layer of the target light-emitting point, while keeping the etching depth of the grating layer of other light-emitting points unchanged, and the number of target light-emitting points is at least one group; S3.3: Sequentially remove the protective layers of other groups of light-emitting points, and after removing the protective layers, use the grating mask pattern as a mask to perform synchronous etching on the grating layer of light-emitting points without protective layers at least once, so that the grating depth of each group of light-emitting points without protective layers increases synchronously, and the depth of light-emitting points without removing protective layers remains unchanged. S3.4: To form different grating etching depths between different groups of light-emitting points.

[0060] When k=1, only one etchant is used. To achieve different depths, a strategy of selective protection and multiple etching is required. First, in step S3.1, except for one group (the target emitting point), the grating layer regions of all other groups of emitting points are covered by a protective layer. Then, in step S3.2, an etching is performed. Since only the target emitting point is not protected, its grating layer etching depth increases, while the grating etching depth of other groups of emitting points remains unchanged. Next, in step S3.3, the protective layers of other groups are removed sequentially. After each group of protective layers is removed, all areas without protective layers are simultaneously etched. For example, after removing the protective layer of the second group, the areas without protective layers include the first and second groups of emitting points. At this time, the first and second groups of emitting points are simultaneously etched. After the second etching, the protective layer of the third group of emitting points is removed, and so on. In this way, the groups whose protective layers are removed first participate in more etching cycles and have greater depths; the groups whose protective layers are removed later participate in fewer etching cycles and have smaller depths. Ultimately, the depths of each group were different.

[0061] It should be noted that in step S3.2 above, the grating layers of all light-emitting points (including those without and with protective layers) can be etched simultaneously. Since the grating layers with protective layers are not etched, the etching depth remains unchanged. Alternatively, the grating layers of light-emitting points without protective layers can be etched synchronously only.

[0062] Furthermore, before forming a protective layer on all other groups of luminescent points besides the first group, the process also includes: Using the grating mask pattern as a mask, the grating layer of all light-emitting points is synchronously initially etched to form an initial etching depth; the initial etching depth is less than or equal to the minimum value of the grating etching depth.

[0063] Understandably, before employing step S3.1, a global initial etching can be added. This initial etching is performed simultaneously on all light-emitting points, ensuring that all groups of light-emitting points achieve a common initial depth. This initial depth can be set equal to the depth of the shallowest group of light-emitting points in the final depth (i.e., the minimum value). Thus, in subsequent selective etching, the light-emitting points in this shallowest group are always protected, their depth reaching their target depth during the first etching step (global initial etching) and remaining unchanged in subsequent etching steps, thereby reducing etching steps and simplifying the process. Alternatively, the initial depth can be less than the minimum value, used to increase the overall depth and facilitate control of etching uniformity. By adjusting the initial depth, the absolute value of the final depth of each group can be flexibly controlled while maintaining a constant depth difference between groups.

[0064] Furthermore, when k≠1, the steps of simultaneously forming different grating etching depths corresponding to N sets of light-emitting points include: When k equals N, t equals 1. Through a single etching process, different types of etchants are applied to different groups of light-emitting point regions. By utilizing different etchants corresponding to different etching rates, N different etching depths are formed in the grating layers of different groups of light-emitting points within the same etching time.

[0065] Understandably, if the number of etchant types, k, is exactly equal to the number of light-emitting point groups, N, that need to be distinguished, then only one etching operation is required (t=1). Specifically, in a single etching process, different types of etchants are applied to different groups of light-emitting point regions. Since each etchant has a different etching rate, within the same etching time, each group of grating layers will be etched to different depths. For example, with 3 groups of light-emitting points, using 3 different etchants, etching rates v1, v2, and v3, and an etching time of T, the depths will be v1*T, v2*T, and v3*T, respectively, and will be different from each other. This method is the most efficient, requiring no multiple etching operations or protective layers.

[0066] Furthermore, when k≠1, the steps of simultaneously forming different grating etching depths corresponding to N sets of light-emitting points include: When k is less than N, t is greater than or equal to log0. k N, through t etching processes, in each etching process, different etchants or protective layers are selectively applied to the grating layer of different groups of light-emitting points, so that the cumulative etching depth of each group of light-emitting points forms N different combination values, thereby distinguishing N different etching depths with less than or equal to N etching processes.

[0067] Understandably, when the number of etchant types k is less than the number of groups N to be distinguished, it is impossible to directly form N different depths through a single etching operation. However, this can be achieved through multiple etching operations (t times). In each etching operation, the type of etchant (or protective layer) applied to each group can be freely chosen, resulting in N different combinations of cumulative etching depths for each group after t etching operations.

[0068] This is similar to k-ary encoding: each etchant is treated as a "number", and the depth sequence after t etchings constitutes a t-bit k-ary number, with a total of k. t There are several combinations. Therefore, as long as k... t If the sum is greater than or equal to N, then N different depths can be distinguished. The smallest integer t satisfying this condition is logt. k Rounding up N. For example, if k=2 (two etchants) and N=4 (requiring 4 depths), then t≥log24=2, meaning that two etching operations can generate 4 different cumulative depths through binary combinations. During each etching operation, different etchants or protective layers are selectively applied to different groups, where the protective layer is equivalent to zero etching, thus achieving the desired combination. This method significantly reduces the number of etching operations, especially suitable for cases where N is large.

[0069] In summary, the method for fabricating the semiconductor laser device 100 provided in this embodiment of the invention solves the problem of fabricating multiple gratings with different polarization states on the same chip in the prior art through ingenious process design, and provides a feasible solution for the industrialization of high-performance, low-cost dual-polarization VCSEL arrays.

[0070] This invention also provides a device including the semiconductor laser device 100 described in the above embodiments. This device can be a 3D imaging device, a high-precision sensing device, a structured light coding device, or a polarization optical detection device, etc., utilizing the various polarization states of laser light provided by the semiconductor laser device 100 of this invention to achieve corresponding functions.

[0071] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a semiconductor laser device, used to fabricate a semiconductor laser device integrating multiple light-emitting points, characterized in that, Includes the following steps: An epitaxial structure is provided, wherein the surface of the epitaxial structure has a grating layer; A grating mask pattern covering all light-emitting point areas and having the same extension direction is formed on the grating layer; Based on the grating mask pattern, different grating etching depths are formed simultaneously for N groups of light-emitting points using k etchants and t etching processes, thereby enabling different groups of light-emitting points to emit lasers with different polarization states; each etchant corresponds to a different etching rate; Where k and t are both positive integers, and when k ≠ 1, t is equal to or greater than logt. k The smallest positive integer N; when k = 1, t is greater than or equal to N.

2. The method for fabricating a semiconductor laser device according to claim 1, characterized in that, When k=1, the step of synchronously forming different grating etching depths corresponding to N groups of light-emitting points specifically includes: A protective layer is formed in the grating layer region corresponding to the other groups of light-emitting points besides the target light-emitting point; Using the grating mask pattern as a mask, the grating layer of at least the target light-emitting point is etched to increase the etching depth of the grating layer of the target light-emitting point, while the etching depth of the grating layer of other groups of light-emitting points remains unchanged, and the number of the target light-emitting points is at least one group; The protective layers of the other groups of light-emitting points are removed in sequence. After the protective layers are removed, the grating mask pattern is used as a mask to perform synchronous etching on the grating layer of the light-emitting points without protective layers at least once, so that the grating depth of each group of light-emitting points without protective layers increases synchronously, and the depth of the light-emitting points without protective layers remains unchanged. Different grating etching depths are formed between different groups of light-emitting points.

3. The method for fabricating a semiconductor laser device according to claim 2, characterized in that, Before forming a protective layer on all other groups of luminescent points except the first group, the process also includes: Using the grating mask pattern as a mask, the grating layer of all light-emitting points is synchronously initially etched to form an initial etching depth; the initial etching depth is less than or equal to the minimum value of the grating etching depth.

4. The method for fabricating a semiconductor laser device according to claim 1, characterized in that, When k≠1, the step of synchronously forming different grating etching depths corresponding to N groups of light-emitting points includes: When k equals N, t equals 1. Through a single etching process, different types of etchants are applied to different groups of light-emitting point regions. By utilizing different etchants corresponding to different etching rates, N different etching depths are formed in the grating layers of different groups of light-emitting points within the same etching time.

5. The method for fabricating a semiconductor laser device according to claim 1, characterized in that, When k≠1, the step of synchronously forming different grating etching depths corresponding to N groups of light-emitting points includes: When k is less than N, t is greater than or equal to log0. k N, through t etching processes, in each etching process, different etchants or protective layers are selectively applied to the grating layer of different groups of light-emitting points, so that the cumulative etching depth of each group of light-emitting points forms N different combination values, thereby distinguishing N different etching depths with less than or equal to N etching processes.

6. A semiconductor laser device, characterized in that, Made by the method of fabricating a semiconductor laser device according to any one of claims 1-5, comprising: Multiple light-emitting points, each of which includes a grating layer; The multiple light-emitting points are divided into multiple groups, and the grating layers of the light-emitting points in different groups have the same extension direction and different etching depths; The etching depth of the light-emitting points in different groups corresponds to different relative dichroisms, so that the light-emitting points in each group emit lasers with different polarization states.

7. The semiconductor laser device according to claim 6, characterized in that, In one of the multiple groups of light-emitting points, the multiple light-emitting points are connected in series or in parallel, and the light-emitting points in different groups are configured to be energized simultaneously or independently.

8. The semiconductor laser device according to claim 6, characterized in that, Each of the light-emitting points is further provided with a PIN photodiode in its corresponding epitaxial structure for monitoring the output power of the corresponding light-emitting point.

9. The semiconductor laser device according to claim 6, characterized in that, The light-emitting points of different groups are arranged alternately so that when light is emitted from different groups of light-emitting points, the light spots emitted from each group roughly overlap in space.

10. A device, characterized in that, Includes the semiconductor laser device as described in any one of claims 6-9.

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