Distributed photonic crystal semiconductor laser and design method thereof

Abstract

The invention provides a distributed photonic crystal semiconductor laser and a design method thereof, and is applied to the field of semiconductor lasers. The semiconductor laser comprises a substrate, an N-type limiting layer, a distributed photonic crystal layer, an N-type waveguide layer, an active layer, a P-type waveguide layer and a P-type limiting layer which are sequentially stacked from bottom to top, wherein the distributed photonic crystal layer comprises high-refractive-index layers and low-refractive-index layers which are alternately stacked, the thickness distribution of the photonic crystal layer is completely non-periodic, and the thickness of each refractive-index layer can be any value and does not follow a fixed period or uniform thickness constraint any more. Through the structure and the design method thereof, the far-field energy divergence angle of the semiconductor laser can be effectively reduced.

Description

Technical Field

[0001] This application relates to the field of semiconductor lasers, and more specifically, to a distributed photonic crystal semiconductor laser and its design method. Background Technology

[0002] Semiconductor lasers, with their core advantages of small size, low power consumption, high conversion efficiency, and high reliability, have become key components in the field of optoelectronics, widely used in optical communication, laser display, precision manufacturing, biosensing, medical diagnostics, and many other important areas. As downstream applications continue to expand, increasingly stringent requirements are being placed on the beam quality of semiconductor lasers. Among these, the far-field energy divergence angle, a key performance indicator directly affecting beam collimation, focusing accuracy, and energy transmission efficiency, has become one of the core directions for technological breakthroughs in the industry.

[0003] The magnitude of the far-field energy divergence angle directly determines the practical application effect of the laser beam: in long-distance optical communication scenarios, a large divergence angle causes rapid energy diffusion during beam transmission, significantly reducing signal transmission efficiency and the signal-to-noise ratio at the receiver; in precision laser processing and micro-device lithography, an excessively large divergence angle leads to an increased focused spot size, failing to meet high-precision processing requirements; in biomedical and laser sensing fields, uncontrolled divergence angle affects detection resolution and operational accuracy. Therefore, reducing the far-field energy divergence angle is a core requirement for enhancing the application value of semiconductor lasers.

[0004] To address the aforementioned issues, various optimization schemes have been proposed in existing technologies, such as adjusting the total thickness of the photonic crystal layer and optimizing the refractive index and thickness of a single layer. However, these schemes still have significant technical limitations: First, traditional designs often rely on empirical formulas or local parameter fine-tuning, lacking global collaborative optimization of parameters across multiple functional layers such as the substrate, confinement layer, photonic crystal layer, and active layer. This makes it difficult to balance the relationship between light field confinement capability, mode selection characteristics, and divergence angle suppression effect, limiting optimization potential. Second, existing photonic crystal layers often employ single-dimensional designs, failing to fully utilize the light field modulation effect of composite structures formed by alternating layers of materials with different refractive indices. Third, the lack of efficient global optimization methods in the multi-parameter optimization process means that traditional algorithms are prone to getting trapped in local optima, resulting in long design cycles, difficulty in accurately obtaining optimal parameter combinations, and an inability to maximize divergence angle suppression.

[0005] Furthermore, current technologies for photonic crystal laser design lack systematic consideration, failing to develop a collaborative design approach for controlling waveguide layer thickness and refractive index difference, and lacking efficient intelligent algorithms for global optimization of multiple parameters. This results in the far-field energy divergence angle of semiconductor lasers still failing to meet the high-precision requirements of advanced applications. Therefore, how to significantly reduce the far-field energy divergence angle through reasonable photonic crystal layer structure design and efficient multi-parameter optimization methods has become a critical technological bottleneck that urgently needs to be overcome in the field of semiconductor lasers. Summary of the Invention

[0006] In view of this, this application provides a distributed photonic crystal semiconductor laser and its design method. By adopting a specific stacked structure of distributed photonic crystal layers and combining a design method that uses a genetic algorithm to globally optimize the parameters of the multifunctional layer, the far-field energy divergence angle of the distributed photonic crystal semiconductor laser can be effectively reduced, and the beam collimation and application adaptability can be improved.

[0007] The first aspect of this application provides a distributed photonic crystal semiconductor laser, comprising: a substrate, an N-type confinement layer, a distributed photonic crystal layer, an N-type waveguide layer, an active layer, a P-type waveguide layer, and a P-type confinement layer stacked sequentially from bottom to top; wherein the distributed photonic crystal layer comprises alternating layers of high refractive index layer and low refractive index layer, and the refractive index of the high refractive index layer is higher than that of the low refractive index layer.

[0008] In this embodiment, a P-type contact layer is also stacked on the surface of the P-type confinement layer, and the P-type contact layer covers the P-surface electrode, forming an ohmic contact between the P-type contact layer and the P-surface electrode.

[0009] In this embodiment, the substrate is disposed on the N-side electrode.

[0010] In this embodiment, in the distributed photonic crystal layer, high refractive index layers and low refractive index layers are alternately stacked along the epitaxial growth direction.

[0011] In this embodiment, the distributed photonic crystal layer is disposed between the N-type confinement layer and the active layer, located on the N-type doped side of the semiconductor laser; the distributed photonic crystal layer may also be disposed between the P-type waveguide layer and the active layer, located on the P-type doped side of the semiconductor laser.

[0012] The second aspect of this application provides a design method for a distributed photonic crystal semiconductor laser, applicable to the distributed photonic crystal semiconductor laser of any one of the first aspects of this application. The method includes: step S1, selecting multiple functional layers of the semiconductor laser to be designed, and recording multiple functional parameters of each functional layer; step S2, creating an initial population containing multiple sets of parameter combinations, each set of parameter combinations including multiple predetermined changes corresponding to multiple functional parameters of each functional layer; step S3, pre-setting the population size, maximum number of iterations, and iteration termination condition of the genetic algorithm to construct an adaptive algorithm aimed at minimizing the divergence angle of the semiconductor laser. The fitness function is used to generate a new population. Step S4 involves performing selection, crossover, and mutation operations on the initial population based on the fitness function. The optimal parameter combination, matching the size of the initial population, is selected from the new population to form the next generation population. Step S5 involves repeating step S4 on the next generation population. Iteration stops when the maximum number of iterations is reached or the divergence angle of the semiconductor laser formed by the functional layers corresponding to the parameter combinations falls below a preset threshold. This yields the optimal population, which is the optimal parameter combination for multiple functional layers. Step S6 involves determining the parameters corresponding to each functional layer in the semiconductor laser based on the optimal parameter combination, thus completing the design of the semiconductor laser.

[0013] In this embodiment, creating an initial population containing multiple sets of parameter combinations includes: for each functional parameter, generating a corresponding predetermined change amount using a random number generation algorithm within a preset range of change.

[0014] In this embodiment, the method further includes: when creating the initial population, validating each set of parameter combinations to ensure that the constraint factor of the structural fundamental mode and the higher-order mode is greater than 2, and ensuring the fundamental mode lasing.

[0015] In this embodiment, in step S4, the selection operation adopts an elite retention strategy, the crossover operation adopts a multi-parameter point crossover algorithm, the mutation operation adopts a random perturbation algorithm based on Gaussian distribution, and after each iteration, the optimal parameter combination is selected from the generated new population as the next generation population through a non-dominated sorting algorithm.

[0016] In this embodiment, in step S5, the iteration stops when the rate of change of the divergence angle is lower than a preset threshold, including: when the rate of change of the divergence angle in the population for 10 consecutive generations is less than 0.1%, it is determined to be converged and the iteration is terminated.

[0017] This application proposes a distributed photonic crystal semiconductor laser and its design method, which has the following advantages:

[0018] (1) Significantly suppress far-field energy divergence angle: By using a distributed photonic crystal layer formed by alternating layers of high-refractive-index and low-refractive-index layers, a flexible optical field control structure system is constructed. Combined with the reasonable stacking of functional layers such as substrate, N-type confinement layer, and active layer, the fundamental mode field can be effectively expanded, the far-field energy divergence angle of semiconductor laser can be greatly reduced, and the beam quality can be improved.

[0019] (2) Achieve global optimal design for multiple parameters: The design method of semiconductor lasers is based on genetic algorithm. Through optimization operations such as elite retention strategy, crossover algorithm, and Gaussian distribution random perturbation mutation, global collaborative optimization of multiple parameters such as thickness and refractive index of each functional layer can be carried out to avoid local optimal solutions, ensure that the combination of device parameters reaches the optimal, and significantly improve design accuracy and reliability. Attached Figure Description

[0020] The embodiments of this application are described below with reference to the accompanying drawings, in which:

[0021] Figure 1 A schematic diagram of a distributed photonic crystal semiconductor laser according to an embodiment of this application is shown.

[0022] Figure 2 A flowchart illustrating a design method for a distributed photonic crystal semiconductor laser according to an embodiment of this application is shown schematically.

[0023] Figure 3 The diagram schematically illustrates the near-field distribution of the fundamental mode of a distributed photonic crystal semiconductor laser according to an embodiment of this application.

[0024] Figure 4 The diagram schematically illustrates the far-field distribution of the fundamental mode of a distributed photonic crystal semiconductor laser according to an embodiment of this application.

[0025] Explanation of reference numerals in the attached figures

[0026] 1-P-type contact layer; 2-P-type confinement layer; 3-P-type waveguide layer; 4-active layer; 5-N-type waveguide layer; 6-high refractive index layer; 7-low refractive index layer; 8-N-type confinement layer; 9-substrate; 10-N-surface electrode; 11-P-surface electrode. Detailed Implementation

[0027] The embodiments of this application will now be described with reference to the accompanying drawings. However, it should be understood that these descriptions are exemplary only and are not intended to limit the scope of this application. In the following detailed description, numerous specific details are set forth to provide a thorough understanding of the embodiments of this application for ease of explanation. However, it will be apparent that one or more embodiments may be implemented without these specific details. Furthermore, descriptions of well-known structures and technologies are omitted in the following description to avoid unnecessarily obscuring the concepts of this application.

[0028] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of this application. The terms “comprising,” “including,” etc., as used herein indicate the presence of features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0029] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein are to be interpreted in a manner consistent with the context of this specification, and not in an idealized or overly rigid way.

[0030] Secondly, this application provides a detailed description in conjunction with schematic diagrams. When detailing the embodiments of this application, for ease of explanation, the cross-sectional views illustrating the device structure may be partially enlarged, not adhering to the usual scale. Furthermore, the schematic diagrams are merely examples and should not limit the scope of protection of this application. In addition, actual fabrication should include three-dimensional spatial dimensions of length, width, and depth.

[0031] Figure 1 A schematic diagram of a distributed photonic crystal semiconductor laser according to an embodiment of this application is shown.

[0032] like Figure 1 As shown in the embodiment of this application, a distributed photonic crystal semiconductor laser includes: a substrate 9, an N-type confinement layer 8, a distributed photonic crystal layer, an N-type waveguide layer 5, an active layer 4, a P-type waveguide layer 3, and a P-type confinement layer 2, which are stacked sequentially from bottom to top; wherein, the distributed photonic crystal layer includes alternating layers of a high refractive index layer 6 and a low refractive index layer 7, and the refractive index of the high refractive index layer 6 is higher than that of the low refractive index layer 7.

[0033] In this embodiment, the refractive index, thickness, and material of the N-type waveguide layer 5, the high refractive index layer 6, and the low refractive index layer 7 can all be set independently.

[0034] Specifically, the refractive index, thickness, and material of each high-refractive-index layer 6 in the distributed photonic crystal layer can be set independently, as can the refractive index, thickness, and material of each low-refractive-index layer 7. Furthermore, the refractive index of each high-refractive-index layer 6 is higher than that of each low-refractive-index layer 7.

[0035] In this embodiment, a P-type contact layer 1 is also stacked on the surface of the P-type confinement layer 2, and the P-type contact layer 1 covers the P-surface electrode 11, forming an ohmic contact between the P-type contact layer 1 and the P-surface electrode 11.

[0036] In this embodiment, the substrate 9 is disposed on the N-side electrode 10.

[0037] In this embodiment, in the distributed photonic crystal layer, the high refractive index layer 6 and the low refractive index layer 7 are alternately stacked along the epitaxial growth direction.

[0038] In this embodiment, the distributed photonic crystal layer can be disposed between the N-type confinement layer 8 and the active layer 4, located on the N-type doped side of the semiconductor laser. Alternatively, it can be disposed between the P-type waveguide layer 3 and the active layer 4, located on the P-type doped side of the semiconductor laser.

[0039] Meanwhile, the distributed photonic crystal layer can also be located on both the N-type doped side and the P-type doped side.

[0040] Figure 2 A flowchart illustrating a design method for a distributed photonic crystal semiconductor laser according to an embodiment of this application is shown schematically.

[0041] like Figure 2 The design method for a distributed photonic crystal semiconductor laser shown is mainly applied to the distributed photonic crystal semiconductor laser of this application. The method includes steps S1 to S6. The specific steps are as follows:

[0042] In step S1, multiple functional layers of the semiconductor laser to be designed are selected, and multiple functional parameters of each functional layer are recorded.

[0043] For example, a semiconductor laser may have multiple functional layers including a distributed photonic crystal layer, an N-side waveguide layer 5, a P-side waveguide layer 3, and a P-type confinement layer 2; wherein the distributed photonic crystal layer comprises multiple high-refractive-index layers 6 and multiple low-refractive-index layers 7 stacked alternately. Functional parameters include at least one of thickness and refractive index.

[0044] In step S2, an initial population containing multiple sets of parameter combinations is created, each set of parameter combinations including multiple predetermined changes corresponding to multiple functional parameters of each functional layer.

[0045] For example, the initial population is a set of multiple parameter combinations, each corresponding to a complete semiconductor laser design. The predetermined change amount refers to the offset of each functional parameter relative to the baseline value recorded in step S1. For example, if the initial thickness of the high refractive index layer 6 is 100 nm, and the predetermined change amount is 20 nm, then its thickness in this parameter combination is 120 nm.

[0046] By generating predetermined variations through randomization, the initial population is evenly distributed within a preset parameter space, avoiding parameter bias caused by manual settings and ensuring that the genetic algorithm can search for the optimal solution from a global perspective, rather than being limited to a local area.

[0047] In this embodiment, creating an initial population containing multiple sets of parameter combinations includes: for each functional parameter, generating a corresponding predetermined change amount using a random number generation algorithm within a preset range of change.

[0048] For each functional parameter, a predetermined change is generated using a uniform random number generation algorithm within its preset range. This ensures that the generated random numbers are evenly distributed within the range of change, guaranteeing that the parameter combinations in the initial population are unbiased and cover the entire search space.

[0049] In this embodiment, when creating the initial population, the validity of each parameter combination is verified to ensure that the constraint factor of the structural fundamental mode and the higher-order mode is greater than 2, thus ensuring the lasing of the fundamental mode.

[0050] For example, after generating the initial parameter combinations, each combination needs to be validated to eliminate invalid combinations that do not meet the key technical constraints, thus avoiding wasting computational resources in subsequent iterations.

[0051] In addition, process feasibility verification (such as whether the actual values ​​of parameters are within the processing range) can be added to further improve the quality of the initial population.

[0052] After validity verification, the resulting multiple sets of valid parameter combinations constitute the final initial population. The population needs to be stored in a structured format (such as a table or array), clearly recording all predetermined variations and actual values ​​for each combination, to facilitate subsequent genetic operations.

[0053] In step S3, the population size, maximum number of iterations, and iteration termination conditions of the genetic algorithm are preset to construct a fitness function with the goal of minimizing the divergence angle of the semiconductor laser.

[0054] For example, population size is the number of parameter combinations in each generation of the population; the more parameter dimensions there are, the larger the population size needs to be. The fitness function is:

[0055]

[0056] in, Let x be the fitness value corresponding to the parameter combination. The far-field energy divergence angle of the semiconductor laser corresponding to parameter combination x. This is a constraint penalty switch used to filter out invalid parameter combinations. This is a penalty coefficient used to amplify the fitness value of ineffective combinations, ensuring that ineffective combinations are eliminated.

[0057] By transforming the engineering goal of reducing the far-field energy divergence angle of semiconductor lasers into a mathematical model that can be executed and quantified by genetic algorithms, such as a fitness function, and setting the algorithm's operating boundary conditions, the algorithm is prevented from searching without limits or deviating from the optimization goal.

[0058] In step S4, based on the fitness function, selection, crossover and mutation operations are performed sequentially on the initial population to generate a new population. The optimal parameter combination with the same number of parameters as the original population is selected from the new population to form the next generation population.

[0059] For example, the first step is selection, which aims to screen for high-quality parent individuals to provide a superior gene pool for subsequent crossover and mutation, preventing the elimination of excellent parameter combinations. Crossover involves exchanging the parameter combinations of parent individuals to generate offspring individuals that possess the superior characteristics of both parents, expanding the parameter search range. Mutation involves applying small-amplitude random perturbations (such as those based on a Gaussian distribution) to some functional parameters of offspring individuals by predetermined changes, generating individuals with new parameter combinations and supplementing population diversity. Compared to a uniform distribution, the perturbation values ​​of a Gaussian distribution are concentrated around the mean (small-amplitude perturbations), with only a low probability of large-amplitude perturbations, which can optimize local parameters while occasionally exploring new regions.

[0060] In this embodiment, the selection operation adopts an elite retention strategy, the crossover operation adopts a multi-parameter point crossover algorithm, the mutation operation adopts a random perturbation algorithm based on Gaussian distribution, and after each iteration, the optimal parameter combination is selected from the generated new population as the next generation population through a non-dominated sorting algorithm.

[0061] For example, the parameters of the distributed photonic crystal layer have a much greater impact on the fitness function than other parameters. Therefore, the high-refractive-index layer 6 and the low-refractive-index layer 7 in the distributed photonic crystal layer are key structures affecting the far-field energy divergence angle, and their parameter combinations directly determine the light field confinement effect. Prioritizing the optimization of these core parameters can quickly narrow the search range for the optimal solution and improve the speed at which the genetic algorithm converges to minimizing the fitness function.

[0062] In step S5, step S4 is repeated for the next generation population. The iteration stops when the maximum number of iterations is reached or the rate of change of the divergence angle of the semiconductor laser composed of the functional layers corresponding to the parameter combination is lower than a preset threshold, and the optimal population is obtained. The optimal population is the optimal parameter combination of multiple functional layers.

[0063] For example, starting with the next generation of the population, the complete genetic operations of selection, crossover, mutation, and screening are repeated in sequence. Each round of the cycle generates a better population, so that the average fitness value of the population (corresponding to the divergence angle) continues to decrease, gradually approaching the global optimum.

[0064] For example, when the number of iterations reaches the maximum number of iterations, such as 150 to 200, the iteration is stopped to avoid excessively long cycles or ineffective iterations that would waste computational resources.

[0065] In this embodiment, the iteration stops when the rate of change of the divergence angle is lower than a preset threshold, including: when the rate of change of the divergence angle is less than 0.1% in 10 consecutive generations of the population, it is determined to be converged and the iteration is terminated.

[0066] Furthermore, the divergence angle of the semiconductor laser formed by the functional layers corresponding to the parameter combinations is less than or equal to a preset threshold, such as 23. ~25 If the setting is determined based on the application scenario, the iteration will terminate directly.

[0067] In step S6, the parameters corresponding to each functional layer in the semiconductor laser are determined according to the optimal parameter combination, thus completing the design of the semiconductor laser.

[0068] The optimal population (optimal parameter combination) obtained in step S5 is transformed into specific and feasible parameters for each functional layer, clarifying key indicators such as the thickness and refractive index of each functional layer, forming a complete semiconductor laser design scheme, and providing a direct basis for subsequent fabrication and processing.

[0069] Figure 3 The diagram schematically illustrates the near-field distribution of the fundamental mode of a distributed photonic crystal semiconductor laser according to an embodiment of this application.

[0070] like Figure 3 As shown, the horizontal axis represents the epitaxial growth direction, with units in micrometers (nm), and the vertical axis represents the relative light field intensity.

[0071] Figure 3 The fundamental mode optical field of the semiconductor laser is not confined to the active region, but extends significantly into the distributed photonic crystal waveguide layer, forming a wide-range, uniform near-field distribution. The optical field intensity exhibits a smooth transition in the active region and the photonic crystal layers on both sides, without obvious abrupt changes or local concentrations, indicating that the distributed photonic crystal structure effectively achieves lateral extension of the optical field.

[0072] Extending the optical field to the photonic crystal layer significantly increases the effective optical field area of ​​the fundamental mode and reduces the far-field divergence angle. At the same time, the distribution density of the optical field in the active region is significantly reduced, which reduces the damage to the active region material caused by excessive local optical field intensity and is conducive to improving the long-term working stability and service life of the laser.

[0073] Figure 4 The diagram schematically illustrates the far-field distribution of the fundamental mode of a distributed photonic crystal semiconductor laser according to an embodiment of this application.

[0074] like Figure 4 As shown, the horizontal axis represents the far-field angle, covering the range of -80° to 80°, and the vertical axis represents the relative light field intensity.

[0075] like Figure 3As can be seen, the full width at half maximum (FWHM) of the far-field intensity is 13.2°, reflecting the core concentration of the beam; the far-field divergence angle corresponding to 95% energy is only 27.4°, successfully compressing this key indicator to within 30°, far exceeding the optimization effect of traditional periodic photonic crystal lasers. The far-field intensity distribution exhibits a symmetrical, smooth single-peak characteristic, with no obvious sidelobes or stray peaks, indicating that the fundamental mode is effectively suppressed, higher-order modes are significantly suppressed, and the beam quality is excellent.

[0076] This demonstrates that the distributed photonic crystal structure optimized by the genetic algorithm solves the technical pain point of traditional photonic crystals having limited ability to reduce the energy divergence angle by 95%.

[0077] On the other hand, the 95% energy divergence angle of 27.4° meets the requirements of efficient optical coupling in practical applications, reduces the precision requirements of the optical system, increases the tolerance space for optical system design, and significantly improves the adaptability and practicality of the laser in scenarios such as pump source, material processing, and optical communication.

[0078] Those skilled in the art will understand that the features described in the various embodiments of this application can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly described in this application. In particular, the features described in the various embodiments of this application can be combined and / or combined in various ways without departing from the spirit and teachings of this application. All such combinations and / or combinations fall within the scope of this application.

Claims

1. A distributed photonic crystal semiconductor laser, characterized in that, include: The substrate (9), N-type confinement layer (8), distributed photonic crystal layer, N-type waveguide layer (5), active layer (4), P-type waveguide layer (3), and P-type confinement layer (2) are stacked sequentially from bottom to top. The distributed photonic crystal layer includes alternating layers of high refractive index layer (6) and low refractive index layer (7), wherein the refractive index of the high refractive index layer (6) is higher than that of the low refractive index layer (7).

2. The semiconductor laser according to claim 1, characterized in that, The surface of the P-type confinement layer (2) is also stacked with a P-type contact layer (1), and a P-type surface electrode (11) is covered on the P-type contact layer (1), and the P-type contact layer (1) and the P-type surface electrode (11) form an ohmic contact.

3. The semiconductor laser according to claim 1, characterized in that, The substrate (9) is disposed on the N-side electrode (10).

4. The semiconductor laser according to claim 1, characterized in that, In the distributed photonic crystal layer, the high refractive index layer (6) and the low refractive index layer (7) are stacked alternately along the epitaxial growth direction.

5. The semiconductor laser according to claim 1, characterized in that, The distributed photonic crystal layer is disposed between the N-type confinement layer (8) and the active layer (4), and is located on the N-type doped side of the semiconductor laser; The distributed photonic crystal layer can also be disposed between the P-type confinement layer (2) and the active layer (4), located on the P-type doped side of the semiconductor laser.

6. A design method for a distributed photonic crystal semiconductor laser, applied to the distributed photonic crystal semiconductor laser according to any one of claims 1 to 5, characterized in that, The method includes: Step S1: Select multiple functional layers of the semiconductor laser to be designed, and record multiple functional parameters of each functional layer. Step S2: Create an initial population containing multiple sets of parameter combinations, where each set of parameter combinations includes multiple predetermined changes corresponding to multiple functional parameters of each functional layer. Step S3: Preset the population size, maximum number of iterations, and iteration termination conditions of the genetic algorithm to construct a fitness function with the goal of minimizing the divergence angle of the semiconductor laser; Step S4: Based on the fitness function, perform selection, crossover and mutation operations on the initial population in sequence to generate a new population, and select the optimal parameter combination with the same number of parameters as the original population from the new population to form the next generation population. Step S5: Repeat step S4 for the next generation population. Stop iterating when the maximum number of iterations is reached or the divergence angle of the semiconductor laser formed by the functional layer corresponding to the parameter combination is lower than a preset threshold, and obtain the optimal population. The optimal population is the optimal parameter combination of the multiple functional layers. Step S6: Determine the parameters corresponding to each functional layer in the semiconductor laser based on the optimal parameter combination, and complete the design of the semiconductor laser.

7. The method according to claim 6, characterized in that, The creation of an initial population comprising multiple sets of parameter combinations includes: For each of the aforementioned functional parameters, a predetermined change amount is generated using a random number generation algorithm within a preset range of change; The functional parameters include at least one of thickness and refractive index.

8. The method according to claim 6, characterized in that, The method further includes: When creating the initial population, the validity of each set of parameters is verified to ensure that the constraint factor of the structural fundamental mode and the higher-order mode is greater than 2, and to ensure the lasing of the fundamental mode.

9. The method according to claim 6, characterized in that, In step S4, the selection operation adopts an elite retention strategy, the crossover operation adopts a multi-parameter point crossover algorithm, the mutation operation adopts a Gaussian distribution-based random perturbation algorithm, and after each iteration, the optimal parameter combination is selected from the generated new population as the next generation population through a non-dominated sorting algorithm.

10. The method according to claim 6, characterized in that, In step S5, the iteration stops when the rate of change of the divergence angle is lower than a preset threshold, including: When the rate of change of the divergence angle is less than 0.1% over 10 consecutive generations of the population, it is determined to be converged and the iteration is terminated.

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