Micro-LED device and preparation method and design device thereof, and design method of metasurface structure

Abstract

The invention provides a Micro-LED device, a preparation method and a design device thereof, and a design method of a metasurface structure, and relates to the technical field of Micro-LEDs. The phase distribution of the metasurface structure is initially designed according to a target light beam angle deflection value, and the initial phase distribution is obtained. Taking a phase coefficient of the initial phase distribution as a current phase coefficient, and constructing a current metasurface structure according to the current phase coefficient; and a plurality of simulation point light sources are used for emitting light to the current metasurface structure to obtain light field distribution. The method comprises the following steps: firstly, calculating a current evaluation value according to phase distribution of light field distribution, and finally, adjusting a current phase coefficient according to the current evaluation value until a preset iteration end condition is met at present, thereby obtaining optimal phase distribution. According to the technical scheme, through the design of simulation of the multiple simulation point light sources and phase iterative optimization, precise regulation and control of the light beam direction of the Micro-LED are achieved, and the illumination precision and the energy utilization efficiency are improved.

Description

Technical Field

[0001] This invention relates to the field of Micro-LED technology, and in particular to a Micro-LED device and its fabrication method, design apparatus, and metasurface structure design method. Background Technology

[0002] Micro-light-emitting diodes (Micro-LEDs) are LED devices with a chip size of less than 100μm. Compared to halogen lamps, xenon lamps, and ordinary LED lamps commonly used in traditional automotive lighting, Micro-LEDs have significant advantages: a contrast ratio exceeding 1,000,000:1, high brightness, excellent color rendering, low energy consumption, long lifespan exceeding 100,000 hours, high pixel density, and support for fine-tuned light field control, making them promising for applications in the automotive lighting field.

[0003] However, Micro-LEDs are Lambertian light sources, and their luminous intensity exhibits a cosine distribution within a range of ±90°. When the half-divergence angle is 60°, the luminous flux within this angle range accounts for 75% of the total luminous flux. This luminous intensity distribution leads to two key problems: first, large-angle light rays easily cause crosstalk between adjacent pixels, severely affecting lighting accuracy and easily resulting in blind spots at road edges or insufficient brightness in the central area; second, a large amount of light cannot be effectively utilized due to the excessively large divergence angle, causing a significant reduction in system energy utilization.

[0004] Traditional optical control solutions for automotive headlights, such as those using reflectors or multi-lens assemblies, suffer from drawbacks such as large size, heavy weight, and poor integration, making it difficult to achieve efficient collimation in the micro-scale scenario of Micro-LEDs. Summary of the Invention

[0005] The first aspect of this invention aims to provide a design method for metasurface structures in Micro-LED devices, thereby solving the problems of severe glare, insufficient lighting accuracy, low energy utilization, and poor integration of traditional optical solutions caused by the Lambertian radiation characteristics of Micro-LEDs when applied to automotive headlights.

[0006] The second aspect of this invention aims to provide a method for fabricating a Micro-LED device.

[0007] The third aspect of this invention aims to provide a Micro-LED device.

[0008] The fourth aspect of this invention aims to provide a design apparatus for Micro-LED devices.

[0009] According to a first aspect of the present invention, the present invention provides a design method for a metasurface structure in a Micro-LED device, the Micro-LED device comprising a first Micro-LED array stacked thereon, an aperture assembly, and a metasurface structure, the first Micro-LED array comprising a plurality of first light sources arranged in an array, the aperture assembly comprising a plurality of apertures corresponding one-to-one with the first light sources, and the design method comprising the following steps: Obtain the target beam angle deflection value; Based on the target beam angle deflection value, the phase distribution of the metasurface structure is preliminarily designed to obtain an initial phase distribution; The phase coefficients of the initial phase distribution are used as the current phase coefficients, and the current metasurface structure is constructed based on the current phase coefficients. Multiple simulated point light sources emit light to the current metasurface structure to obtain the light field distribution of the light emitted by the multiple simulated point light sources after passing through the current metasurface structure; The current evaluation value is calculated based on the phase distribution of the light field distribution; The current phase coefficient is adjusted based on the current evaluation value until the preset iteration end condition is met, thereby obtaining the optimal phase distribution; Wherein, the absolute value of the divergence angle of the light rays emitted from the metasurface structure corresponding to the optimal phase distribution is less than or equal to a set angle.

[0010] Optionally, the step of emitting light from multiple simulated point light sources to the current metasurface structure to obtain the light field distribution of the light emitted from the multiple simulated point light sources after passing through the current metasurface structure specifically includes the following steps: Calculate the complex amplitude of the light rays emitted from the plurality of simulated point light sources after being modulated by the current metasurface structure; Based on the propagation distance, wavenumber, center wavelength of the light source, spatial frequency of the light field in the X-axis direction and spatial frequency in the Y-axis direction of the light field formed by the multiple simulated point light sources, the light field transfer function of angular spectrum propagation is calculated. The light field distribution is calculated based on the complex amplitude and the light field transfer function.

[0011] Optionally, the step of calculating the complex amplitude of the light emitted from the plurality of simulated point light sources after being modulated by the current metasurface structure specifically includes the following steps: The initial complex amplitude of each of the simulated point light sources is calculated based on the wave number and the distance from the multiple simulated point light sources to the observation point. The complex amplitude is calculated based on the initial complex amplitude and the phase distribution of the current metasurface structure.

[0012] Optionally, based on the propagation distance, wavenumber, center wavelength of the light source, spatial frequency of the light field in the X-axis direction, and spatial frequency of the light field in the Y-axis direction formed by the plurality of simulated point light sources, the light field transfer function for angular spectrum propagation is calculated, specifically including: Calculate the product of the center wavelength of the light source and the first spatial frequency to obtain the first intermediate quantity; Calculate the product of the center wavelength of the light source and the second spatial frequency to obtain the second intermediate quantity; The optical field transfer function is calculated based on the first intermediate quantity, the second intermediate quantity, the optical field propagation distance, and the wavenumber; the first spatial frequency is the spatial frequency of the optical field in the X-axis direction, and the second spatial frequency is the spatial frequency of the optical field in the Y-axis direction. And / or, the optical field distribution is calculated based on the complex amplitude and the optical field transfer function, specifically including: Perform a Fourier transform on the complex amplitude to obtain the transformed complex amplitude; The transformed complex amplitude is calculated as a product of the optical field transfer function to obtain the transformed square distribution; The light field distribution is obtained by performing an inverse Fourier transform on the transformed square distribution; And / or, based on the wavenumber and the distance from the plurality of simulated point light sources to the observation point, the initial complex amplitude of each of the simulated point light sources is calculated, specifically including: The third intermediate quantity is obtained by calculating the product of the wave number and the distance from the plurality of simulated point light sources to the observation point; Calculate the complex number of the third intermediate quantity to obtain the fourth intermediate quantity; The initial complex amplitude is obtained by calculating the ratio of the fourth intermediate quantity to the distance from the plurality of simulated point light sources to the observation point; And / or, the complex amplitude is calculated based on the initial complex amplitude and the phase distribution of the current metasurface structure, specifically including: Calculate the complex number of the phase distribution of the current metasurface structure to obtain the complex phase distribution; The complex amplitude is obtained by calculating the product of the initial complex amplitude and the complex phase distribution.

[0013] Optionally, the step of calculating the current evaluation value based on the phase distribution of the light field distribution specifically includes: When the target beam angle deflection value is 0°, the current evaluation value is calculated based on the number of sampling points in the observation plane, the actual phase value of each sampling point, and the average phase value of all sampling points. When the target beam angle deflection value is not 0°, the current evaluation value is calculated based on the number of sampling points in the observation plane, the ideal phase value of each sampling point, and the actual phase value of each sampling point.

[0014] Optionally, in the step of adjusting the current phase coefficient based on the current evaluation value until the preset iteration termination condition is met, thereby obtaining the optimal phase distribution, If the current iteration count is greater than the preset count or the change in continuous evaluation values ​​is less than the preset value, then the current iteration ends as the preset iteration end condition is met, and the current phase coefficient corresponding to the minimum value among all current evaluation values ​​is taken as the optimal phase coefficient of the optimal phase distribution. Wherein, the continuous evaluation value change amount is the change amount of the current evaluation value for a consecutive preset number of times; And / or, the initial phase distribution is obtained by simulating the phase distribution of the metasurface structure using a binary phase surface, and the initial phase distribution satisfies the following polynomial: ; Where R represents the normalized radius of the binary phase surface. Let m be the radial position on the metasurface structure, and m be the polynomial number. For phase coefficients, This indicates the target beam angle deflection value. Represents the phase distribution function. The wavelength is the center wavelength of the light source; And / or, the set angle is 50°-70°.

[0015] According to a second aspect of the present invention, the present invention provides a method for fabricating a Micro-LED device, comprising: Provide a first Micro-LED array; An aperture assembly and a metasurface structure are sequentially fabricated on the first Micro-LED array; wherein the phase distribution of the metasurface structure is obtained using the design method described above.

[0016] According to a third aspect of the present invention, the present invention provides a Micro-LED device, obtained by the above-described fabrication method, comprising: The first Micro-LED array includes multiple arrays of first light sources; An aperture assembly is located above the first Micro-LED array and includes multiple holes corresponding to the first light source, with the first light source disposed within the corresponding holes; A metasurface structure, located above the aperture assembly, is used to regulate the light after it passes through the aperture assembly.

[0017] Optionally, the Micro-LED device further includes a second Micro-LED array, the second Micro-LED array including a plurality of second light sources arranged in an array, the second Micro-LED array being disposed around the first Micro-LED array; And / or, the metasurface structure includes a substrate layer and nanopillars disposed on the side of the substrate layer away from the aperture.

[0018] According to a fourth aspect of the present invention, the present invention provides a design apparatus for a Micro-LED device, comprising a processor and a memory interconnected thereto, wherein the processor is configured to execute a computer program stored in the memory to implement the design method described above.

[0019] This invention first designs the phase distribution of the metasurface structure based on the target beam angle deflection value, obtaining an initial phase distribution. Then, the phase coefficient of the initial phase distribution is used as the current phase coefficient, and the current metasurface structure is constructed based on the current phase coefficient. Multiple simulated point light sources emit light onto the current metasurface structure to obtain the light field distribution after the light from the simulated point light sources passes through the current metasurface structure. Then, based on the phase distribution of the light field, the current evaluation value is calculated. Finally, the current phase coefficient is adjusted based on the current evaluation value until the preset iteration termination condition is met, thereby obtaining the optimal phase distribution. This technical solution, through the joint design of multiple simulated point light source simulation and phase iteration optimization, achieves precise control of the beam direction of Micro-LEDs, improves lighting accuracy and energy utilization efficiency, significantly improves the glare problem when Micro-LEDs are applied to automotive headlights, and enhances the miniaturization and integrability of the system.

[0020] The above and other objects, advantages and features of the present invention will become more apparent to those skilled in the art from the following detailed description of specific embodiments of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0021] The following sections will describe some specific embodiments of the invention in detail by way of example and not limitation, with reference to the accompanying drawings. The same reference numerals in the drawings denote the same or similar parts or portions. Those skilled in the art should understand that these drawings are not necessarily drawn to scale. In the drawings: Figure 1 This is a schematic flowchart illustrating a design method for a metasurface structure in a Micro-LED device according to an embodiment of the present invention; Figure 2 yes Figure 1 A schematic flowchart of step S400 in the illustrated embodiment; Figure 3This is a schematic cross-sectional view of a Micro-LED device according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a first Micro-LED array and a second Micro-LED array according to an embodiment of the present invention; Figure 5 (a) is the phase distribution diagram of the metasurface structure when the target beam angle deflection value is 0°; Figure 5 (b) is Figure 5 (a) shows the XZ plane light field distribution diagram. Figure 6 (a) is the phase distribution diagram of the metasurface structure when the target beam angle deflection value is 20°; Figure 6 (b) is Figure 6 (a) shows the XZ plane light field distribution diagram. Figure 7 (a) is the phase distribution diagram of the metasurface structure when the target beam angle deflection value is 40°; Figure 7 (b) is Figure 7 (a) shows the XZ plane light field distribution diagram. Figure 8 (a) is the phase distribution diagram of the metasurface structure when the target beam angle deflection value is 50°; Figure 8 (b) is Figure 8 (a) shows the XZ plane light field distribution diagram. Figure 9 This is an emitted light field diagram of a Micro-LED device according to an embodiment of the present invention.

[0022] Figure label: 100-Micro-LED device, 10-First Micro-LED array, 11-First light source, 20-Aperture assembly, 21-Vacuum hole, 30-Metasurface structure, 31-Substrate layer, 32-Nano pillar, 40-Second Micro-LED array, 41-Second light source. Detailed Implementation

[0023] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0024] In the description of this invention, it should be understood that the terms "upper" and "lower" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. 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. Therefore, they should not be construed as limiting this invention.

[0025] Unless otherwise specified, all terms (including technical and scientific terms) used in the description of this embodiment have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains.

[0026] The Micro-LED device includes a first Micro-LED array stacked together, an aperture assembly, and a metasurface structure. The first Micro-LED array includes multiple first light sources arranged in an array, and the aperture assembly includes multiple apertures that correspond one-to-one with the first light sources.

[0027] like Figure 1 As shown, Figure 1 This is a schematic flowchart illustrating a method for designing a metasurface structure in a Micro-LED device according to an embodiment of the present invention. The method for designing a metasurface structure in a Micro-LED device includes the following steps: Step S100: Obtain the target beam angle deflection value.

[0028] The target beam angle deflection value is a value entered by the user.

[0029] Step S200: Based on the target beam angle deflection value, the phase distribution of the metasurface structure is preliminarily designed to obtain the initial phase distribution.

[0030] Metasurface structures, as micro-nano devices composed of periodic or quasi-periodic subwavelength unit structures, can flexibly control the amplitude and phase of electromagnetic waves, providing an ideal solution for realizing compact, integrated Micro-LED devices for directional lighting and optical communication.

[0031] Furthermore, ray tracing algorithms can be used to optimize the phase design of the metasurface structure in conjunction with the requirements of automotive lighting scenarios to obtain the initial phase distribution; this is existing technology and will not be elaborated upon in this invention.

[0032] Step S300: Use the phase coefficient of the initial phase distribution as the current phase coefficient, and construct the current metasurface structure based on the current phase coefficient.

[0033] The optimal phase distribution can be obtained by using the particle swarm optimization (PSO) algorithm. Specifically, the phase coefficients of the initial phase distribution are used as "particles" in the PSO algorithm, with each particle corresponding to a set of phase coefficients.

[0034] Step S400: Use multiple simulated point light sources to emit light to the current metasurface structure, so as to obtain the light field distribution of the light emitted by the multiple simulated point light sources after passing through the current metasurface structure.

[0035] Step S500: Calculate the current evaluation value based on the phase distribution of the light field distribution.

[0036] Step S600: Adjust the current phase coefficient according to the current evaluation value until the preset iteration end condition is met, thereby obtaining the optimal phase distribution; wherein, the absolute value of the divergence angle of the light emitted from the metasurface structure corresponding to the optimal phase distribution is less than or equal to the set angle.

[0037] This embodiment achieves precise control of the beam direction of Micro-LED through a joint design of multiple simulated point light sources and phase iteration optimization, improving lighting accuracy and energy utilization efficiency, significantly improving the glare problem when Micro-LED is applied to automotive headlights, and enhancing the miniaturization and integrability of the system.

[0038] In some embodiments, the initial phase distribution is obtained by simulating the phase distribution of a metasurface structure using a binary phase surface, and the initial phase distribution satisfies the following polynomial: Where R represents the normalized radius of the binary phase surface. Let m be the radial position on the metasurface structure, and m be the polynomial number. For phase coefficients, This indicates the target beam angle deflection value. Represents the phase distribution function. The wavelength is the center wavelength of the light source.

[0039] The phase distribution of the metasurface structure is simulated using a binary phase surface. This is achieved by repeatedly adjusting the coefficients of the binary phase surface. Until the emitted light meets the directional requirements of the car headlights.

[0040] This embodiment introduces a deflection phase in the X-axis direction of the metasurface structure, enabling directional deflection of the emitted beam along the X-axis. Similarly, introducing a deflection phase in the Y-axis direction allows for directional deflection of the beam along the Y-axis, ultimately meeting the requirements for the directional emission angle of the beam in different scenarios.

[0041] In some embodiments, the angle is set to 50°-70°. The angle can also be determined according to specific design requirements, for example, it can be 50°, 55°, 60°, 65° or 70°.

[0042] like Figure 2 As shown, Figure 2 yes Figure 1 The illustrated embodiment shows a schematic flowchart of step S400. Specifically, it includes the following steps: Step S410: Calculate the complex amplitude of the light emitted from multiple simulated point light sources after being modulated by the current metasurface structure.

[0043] In some embodiments, step S410 specifically includes the following steps: Step S411: Calculate the initial complex amplitude of each simulated point light source based on the wave number and the distance from the multiple simulated point light sources to the observation point.

[0044] The initial complex amplitude of each simulated point light source is expressed as: Where U represents complex amplitude, e represents natural constant, k represents wave number, and r represents distance from point source to observation point.

[0045] This embodiment considers that Micro-LED devices are surface light sources when applied to automotive headlights, and using a single simulated point light source would lead to significant errors. Therefore, this embodiment uses a method of superimposing multiple simulated point light sources to simulate its light field characteristics. Since Micro-LED devices are uncorrelated light sources, the light field simulation employs a superposition method of light intensity from multiple simulated point light sources. While balancing simulation accuracy and computational efficiency, 10 simulated point light sources are arranged on the X-axis (with a 0.5 μm interval between adjacent simulated point light sources). Using angular spectrum propagation theory, the XZ-plane light field distribution of the Micro-LED before and after passing through the metasurface structure is numerically simulated.

[0046] In some embodiments, step S411 specifically includes the following steps: Step S4111: Calculate the product of the wavenumber and the distances from multiple simulated point light sources to the observation point to obtain the third intermediate quantity; Step S4112: Calculate the complex number of the third intermediate quantity to obtain the fourth intermediate quantity; Step S4113: Calculate the ratio of the fourth intermediate quantity to the distance from the multiple simulated point light sources to the observation point to obtain the initial complex amplitude.

[0047] Step S412: Calculate the complex amplitude based on the initial complex amplitude and the phase distribution of the current metasurface structure.

[0048] The complex amplitude of the light emitted from each simulated point source after being modulated by the current metasurface structure is expressed as: in, Indicates complex amplitude. This represents the complex phase distribution.

[0049] In some embodiments, step S412 specifically includes the following steps: Step S4121: Calculate the complex number of the phase distribution of the current metasurface structure to obtain the complex phase distribution.

[0050] Step S4122: Calculate the product of the initial complex amplitude and the complex phase distribution to obtain the complex amplitude.

[0051] Step S420: Based on the propagation distance, wavenumber, center wavelength of the light source, spatial frequency of the light field in the X-axis direction and spatial frequency in the Y-axis direction of the light field formed by multiple simulated point light sources, calculate the light field transfer function for angular spectrum propagation.

[0052] In some embodiments, step S420 specifically includes the following steps: Step S421: Calculate the product of the center wavelength of the light source and the first spatial frequency to obtain the first intermediate quantity.

[0053] Step S422: Calculate the product of the center wavelength of the light source and the second spatial frequency to obtain the second intermediate quantity.

[0054] Step S423: Calculate the light field transfer function based on the first intermediate quantity, the second intermediate quantity, the light field propagation distance, and the wavenumber; the first spatial frequency is the spatial frequency of the light field in the X-axis direction, and the second spatial frequency is the spatial frequency of the light field in the Y-axis direction.

[0055] The optical field transfer function for angular spectrum propagation is: in, Let z represent the light field transfer function, z represent the light field propagation distance, j represent the imaginary unit, and k represent the wave number. Indicates the center wavelength of the light source. and These are the spatial frequencies of the light field in the X-axis and Y-axis directions, respectively.

[0056] Step S430: Calculate the light field distribution based on the complex amplitude and the light field transfer function.

[0057] In some embodiments, step S430 specifically includes the following steps: Step S431: Perform a Fourier transform on the complex amplitude to obtain the transformed complex amplitude.

[0058] Step S432: Calculate the product of the transformed complex amplitude and the optical field transfer function to obtain the transformed square distribution.

[0059] Step S433: Perform an inverse Fourier transform on the transformed square distribution to obtain the light field distribution.

[0060] The light field distribution is represented as: in, Indicates the light field distribution. Indicates Fourier transform, Indicates the transformation of complex amplitude. This represents the inverse Fourier transform.

[0061] In some embodiments, In light field simulation, `angle` is a complex argument function, also known as the "phase function," and its core function is to determine the light field distribution. Phase data is extracted from the angle (in this embodiment). The extracted value is the actual phase value of the sampling point of the emitted light field after being modulated by the metasurface structure.

[0062] In some embodiments, step S500 specifically includes: Step S510: When the target beam angle deflection value is 0°, the current evaluation value is calculated based on the number of sampling points in the observation plane, the actual phase value of each sampling point, and the average phase value of all sampling points.

[0063] When the target beam angle deflection is 0°, the current evaluation value is the first evaluation value, which is expressed as: in, This represents the first evaluation value, and N represents the number of sampling points within the observation plane. This represents the actual phase value of the i-th sampling point. This represents the average phase value across all sampling points.

[0064] This can be understood as follows: when the target beam angle deflection is 0°, it refers to a collimated scene, where the phase distribution of the outgoing light field tends to be a plane wave, and the first evaluation value is the standard deviation of the phase distribution in the observation plane. This embodiment is equivalent to calculating the fitness value of each particle. The smaller the value, the more uniform the phase distribution, the closer the light field is to a plane wave, and the better the collimation effect.

[0065] Step S520: When the target beam angle deflection value is not 0°, calculate the current evaluation value based on the number of sampling points in the observation plane, the ideal phase value of each sampling point, and the actual phase value of each sampling point.

[0066] When the target beam angle deflection value is not 0°, the evaluation value is the second evaluation value, which is expressed as: in, This indicates the second evaluation value. , Indicates the ideal phase value. This represents the ideal phase value of the i-th sampling point. Let N be the actual phase value of the i-th sampling point, and let N represent the number of sampling points in the observation plane.

[0067] This can be understood as follows: when the target beam angle deflection value is not 0°, it refers to a directional deflection scenario, where the phase distribution of the outgoing light field conforms to a fixed deflection angle. The phase law of plane waves, the ideal phase is The second evaluation value is the mean square error between the actual phase and the ideal phase. The smaller the value, the closer the actual phase matches the ideal phase, the closer the light field is to a plane wave emitted at a fixed angle, and the better the directional effect.

[0068] In some embodiments, in step S600, if the current iteration number is greater than a preset number or the change in continuous evaluation values ​​is less than a preset value, then it is determined that the preset iteration termination condition is met, and the current phase coefficient corresponding to the minimum value among all current evaluation values ​​is taken as the optimal phase coefficient of the optimal phase distribution; wherein, the change in continuous evaluation values ​​is the change in a preset number of consecutive current evaluation values. Specifically, the first preset number can be determined according to specific design requirements, for example, it can be 300 times, 400 times, 500 times, etc. The second preset number can be set to 10 times. The preset value can be set to 10. -5 In other embodiments, the first preset number of times, the second preset number of times, and the preset value can also be determined according to specific design requirements.

[0069] Furthermore, in each iteration, the velocity and position of each particle are updated based on its individual optimal fitness (i.e., the minimum evaluation value obtained by a single particle during iteration) and the global optimal fitness (the minimum evaluation value obtained by all particles during iteration). Finally, the phase coefficient corresponding to the global optimal fitness is determined as the optimal phase coefficient. In each iteration, the particle velocity update uses a collaborative formula that integrates the inertia term, the individual learning term, and the global learning term. Specifically, the phase coefficient a corresponding to the i-th particle... n The speed v of the next iteration n i (t+1) equals the inertial weight ω (value 0.7) and the current velocity v. n i The product of (t), plus the individual learning factor c1 (value 2), the random number r1 (uniformly distributed in [0,1]), and the particle's current position a n i (t) and its own historical best position a n pbest iThe product of the differences, plus the global learning factor c2 (value 2), the random number r2 (uniformly distributed in [0,1]), and the particle's current position a n i (t) and the global optimal position of all particles a n The product of the differences between ,gbest and , and the updated speed must be constrained within the range of [-10, 10] (to avoid excessive adjustment range leading to convergence disorder); the particle position update directly sets the current position a. n i (t) and the updated velocity v n i Adding (t+1) gives the position a of the next iteration. n i (t+1), while ensuring that the new position falls within the initial phase coefficient a n 0 Within the corresponding interval [-50, +50] (i.e., a) n i (t+1)∈[a n 0 -50,a n 0 +50]), when exceeding the boundary, the corresponding boundary value is taken. Through this update logic, the particles can both explore a better coefficient space by relying on inertia and converge accurately under the guidance of individual optimality and global optimality, ultimately approaching the optimal phase coefficient. It is worth noting that the specific process of the particle swarm algorithm can be referred to existing technology, and this implementation will not be described in detail.

[0070] Through the above optimization, this embodiment finally obtains a phase coefficient that meets the collimation or orientation requirements, and then obtains the optimal phase distribution of the metasurface according to the phase formula.

[0071] In some embodiments, the present invention also provides a method for fabricating a Micro-LED device, comprising the following steps: Step 1: Provide a first Micro-LED array.

[0072] Step 2: Sequentially fabricate an aperture assembly and a metasurface structure on the first Micro-LED array; wherein the phase distribution of the metasurface structure is obtained using the design method of any of the above embodiments.

[0073] The metasurface structure in this embodiment is realized on a GaN substrate using a gradient-distributed array of circular GaN nanostructures. The GaN nanostructures have a periodic square lattice (P=300nm) and circular nanostructures of different sizes (all nanostructures have a fixed height of H=500nm). The nanopillars arranged on the GaN substrate have structural diameters ranging from 60nm to 280nm, and the phase and transmission optical responses of different diameters at a design wavelength of 532nm provide a database for the design of the proposed metasurface structure. Specifically, by placing an x-polarized or y-polarized light source with a wavelength of 532nm in the GaN substrate, assuming perfect layer matching along the z-direction, and periodic boundary conditions along the x and y directions (period P=300nm), the overall phase of the nanopillars covers the range of 0~2π, and the average transmittance of all nanopillars is above 70%, providing data support for the design and arrangement of the metasurface structure. Different GaN nanopillars of different sizes correspond to different transmittance and phase response. The mapping relationship between the phase required by the metasurface structure and the size of the GaN nanopillars can be selected from the established database. Finally, the schematic diagram of the metasurface structure is arranged using Klayout software. The front side of the GaN substrate has a metasurface structure with a diameter of 286 μm. This metasurface structure prevents light from escaping at large angles (>±60°) in Micro-LED devices, thereby reducing crosstalk between adjacent pixel units. Light within a certain divergence angle (<±60°) is collimated and emitted after passing through the metasurface structure.

[0074] like Figure 3 As shown, Figure 3 This is a schematic cross-sectional view of a Micro-LED device 100 according to an embodiment of the present invention. The Micro-LED device 100 is obtained by the above-described fabrication method and includes a first Micro-LED array 10, an aperture assembly 20, and a metasurface structure 30.

[0075] The first Micro-LED array 10 includes multiple first light sources 11 arranged in an array. For example, the size of the first light source 11 is 5μm × 5μm, and the center wavelength of the first light source 11 is 532nm.

[0076] The aperture assembly 20 is located above the first Micro-LED array 10 and includes a plurality of holes 21 corresponding one-to-one with the first light source 11, with the first light source 11 disposed within the holes 21. Specifically, the cross-sectional shape of the holes 21 can be rectangular, circular, or other reasonable shapes; for example, the height of the aperture assembly 20 is 5μm, and the diameter of the holes 21 is 22μm.

[0077] The metasurface structure 30 is located above the aperture assembly 20 and is used to regulate the light after passing through the aperture assembly 20.

[0078] like Figure 4 As shown, Figure 4 This is a schematic diagram of a first Micro-LED array 10 and a second Micro-LED array 40 according to an embodiment of the present invention. In some embodiments, the Micro-LED device 100 further includes a second Micro-LED array 40, which includes a plurality of second light sources 41 arranged in an array. The second Micro-LED array 40 is disposed around the first Micro-LED array 10, and the size of the second light source 41 can be 50μm×50μm.

[0079] In some embodiments, such as Figure 4 As shown, the metasurface structure 30 includes a substrate layer 31 and nanopillars 32 disposed on the side of the substrate layer 31 away from the aperture assembly 20.

[0080] Specifically, the first Micro-LED array 10 is an array arrangement, and the first light source 11 is a Micro-LED, with each Micro-LED having a consistent period. The light emitted by the Micro-LEDs follows a Lambertian distribution, with light intensity covering ±90°. When the half-divergence angle is 60°, the luminous flux accounts for 75% of the total luminous flux. This light intensity distribution leads to severe crosstalk at large angles, and a large amount of energy remains unused, resulting in low system energy utilization. The aperture assembly 20 is constructed by coating the first Micro-LED array 10 with black photoresist and fabricating a hole array using photolithography. Furthermore, through the arrangement of a series of subwavelength nanopillars 32, the incident large-angle light is collimated or directionally emitted after the amplitude and phase are modulated by the metasurface structure 30. The nanopillars 32 adopt a periodic square lattice with a period (i.e., the distance between two adjacent nanopillars 32) P=300nm, a fixed height of 500nm, and a diameter that is gradually adjusted in the range of 60nm-280nm according to phase requirements to ensure phase coverage of the 0~2π range and an average transmittance ≥70%, thus guaranteeing illumination efficiency.

[0081] In this embodiment, a black aperture assembly 20 is fabricated on the surface of the first Micro-LED array 10, and then a metasurface structure 30 is aligned and encapsulated on the aperture assembly 20. The ultra-large emission angle light from the Micro-LED array 10 is absorbed by the aperture assembly 20, preventing crosstalk between adjacent pixel units. The light within a certain divergence angle is collimated or directionally emitted after passing through the metasurface structure 30.

[0082] The solution provided in this embodiment is applicable to various vehicle lighting scenarios, including low beam headlights, high beam headlights, turn signals, and fog lights. It particularly meets the high requirements for light source collimation, directionality, anti-interference, and energy utilization during nighttime driving, while also adapting to dynamic lighting needs under complex road conditions. The aperture bracket is tightly fitted to the surface of the Micro-LED array 10, and the center of the aperture is precisely aligned with the individual first light source 11. By precisely adjusting the aperture size and the distance between the aperture and the Micro-LED array 10, normal light emission within a ±60° range is allowed. Simultaneously, large-angle light exceeding ±60° is suppressed through a dual "reflection + absorption" method (the inner wall of the aperture 20 is coated with a high-reflectivity aluminum film, and the outer wall is coated with light-absorbing black glue), avoiding glare and energy waste. In normal large-angle lighting mode, the aperture assembly 20 is not installed at the location of the Micro-LEDs, achieving light emission from -90° to 90°, covering the near-field range in front of and to the sides of the vehicle, meeting the wide field of view requirements for low-speed driving, parking, and passing on narrow roads. In collimated directional emission lighting mode, the beam divergence angle is reduced to ±1° in high beam scenarios, which can meet the collimation requirements of automotive headlights.

[0083] This embodiment features a dual-functional partitioned Micro-LED array (including a first Micro-LED array 10 and a second Micro-LED array 40): employing a "functional partitioning + unit-level controllable" structure, the Micro-LED array is divided into a wide-angle illumination area and a collimated directional illumination area. The wide-angle illumination area (i.e., the area where the second Micro-LED array 40 is located) has an original half-divergence angle of 65°, suitable for wide field-of-view requirements; the collimated directional illumination area (i.e., the area where the first Micro-LED array 10 is located) has an original half-divergence angle of 60°, suitable for precise control requirements; the Micro-LED array is integrated onto a matching dual-channel independent CMOS driver chip (not shown in the figure), supporting partitioned start / stop and unit-level brightness adjustment. In normal wide-angle illumination mode, only the wide-angle illumination area located at the edge is activated; in collimated directional illumination mode, only the collimated directional illumination area located in the center is activated, avoiding mutual interference between the light from the two areas.

[0084] By simulating the above scheme, we obtain... Figures 5 to 9 The results are shown.

[0085] like Figures 5 to 8 As shown, Figure 5 (a) is the phase distribution diagram of the metasurface structure when the target beam angle deflection is 0°. Figure 6 (a) is a phase distribution diagram of a metasurface structure with 20° directional emission according to an embodiment of the present invention. Figure 7 (a) is a phase distribution diagram of a metasurface structure with 40° directional emission according to an embodiment of the present invention. Figure 8(a) is a phase distribution diagram of a metasurface structure with 50° directional emission according to an embodiment of the present invention; wherein the X-axis and Y-axis both represent coordinate positions. Figure 5 (b) is Figure 5 (a) shows the XZ plane light field distribution. Figure 6 (b) is Figure 6 (a) shows the XZ plane light field distribution. Figure 7 (b) is Figure 7 (a) shows the XZ plane light field distribution. Figure 8 (b) is Figure 8 (a) shows the XZ plane light field distribution diagram; where the horizontal axis Z is the light field propagation position and the vertical axis X is the coordinate position.

[0086] The orientation effect can be verified by calculating the actual deflection angle, as follows: The first step is to read the light intensity distribution matrix and calculate the half-peak light intensity. The second step is to locate the beam boundary coordinates: find the beam intensity equal to the x-axis or y-axis direction. Let a and b be the two boundary points.

[0087] The third step is to calculate the divergence angle: based on the observation distance, the divergence angle is calculated using trigonometric functions; Where z is the observation distance.

[0088] like Figure 9 As shown, Figure 9 This is an emitted light field diagram of a Micro-LED device according to an embodiment of the present invention. The horizontal axis Z represents the light field propagation position, and the vertical axis X represents the coordinate position, used to describe the distribution of the emitted light field of the Micro-LED.

[0089] Furthermore, Figure 9 The corresponding divergence angle can be obtained as follows: Step 1, Read Figure 9 The corresponding light intensity distribution matrix yields the peak light intensity I. max ; Calculate the half-peak intensity .

[0090] The second step is to locate the beam boundary coordinates: find the beam intensity equal to the x-axis or y-axis direction. Let a and b be the two boundary points.

[0091] The third step is to calculate the divergence angle: based on the observation distance, the divergence angle is calculated using trigonometric functions; Where z is the observation distance.

[0092] In some embodiments, the present invention also provides a design apparatus for a Micro-LED device, comprising a processor and a memory interconnected thereto. The processor executes a computer program stored in the memory to implement the design method of any of the above embodiments. The processor may be a central processing unit (CPU), a digital processing unit, etc. The processor sends and receives data through a communication interface. The memory stores the program executed by the processor. The memory is any medium capable of carrying or storing desired program code in the form of instructions or data structures and accessible by a computer, and may also be a combination of multiple memories. The aforementioned computational program can be downloaded from a computer-readable storage medium to a corresponding computing / processing device or via a network (e.g., the Internet, a local area network, a wide area network, and / or a wireless network) to a computer or external storage device.

[0093] Therefore, those skilled in the art should recognize that although numerous exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications conforming to the principles of the present invention can be directly determined or derived from the disclosure of the present invention without departing from the spirit and scope of the invention. Thus, the scope of the present invention should be understood and construed as covering all such other variations or modifications.

Claims

1. A method for designing a metasurface structure in a Micro-LED device, characterized in that, The Micro-LED device comprises a first Micro-LED array, a light diaphragm assembly and a metasurface structure arranged in layers, the first Micro-LED array comprises a plurality of arrayed first light sources, the light diaphragm assembly comprises a plurality of light diaphragms corresponding to the first light sources one by one, and the design method comprises the following steps: Obtain a target beam angle deflection value; According to the target beam angle deflection value, the phase distribution of the metasurface structure is preliminarily designed to obtain an initial phase distribution; The phase coefficient of the initial phase distribution is taken as a current phase coefficient, and a current metasurface structure is constructed according to the current phase coefficient; A plurality of simulated point light sources emit light to the current metasurface structure to obtain the light field distribution of the light emitted by the plurality of simulated point light sources after passing through the current metasurface structure; According to the phase distribution of the light field distribution, a current evaluation value is calculated; According to the current evaluation value, the current phase coefficient is adjusted until the current satisfies a preset iteration end condition, so as to obtain an optimal phase distribution; Wherein, the absolute value of the divergence angle of the light emitted from the metasurface structure corresponding to the optimal phase distribution is less than or equal to a set angle.

2. The design method of claim 1, wherein The step of utilizing a plurality of simulated point light sources to emit light to the current metasurface structure to obtain the light field distribution of the light emitted by the plurality of simulated point light sources after passing through the current metasurface structure comprises the following steps: Calculate the complex amplitude of the light emitted by the plurality of simulated point light sources after passing through the current metasurface structure modulation; Based on the propagation distance, wave number, light source center wavelength, spatial frequency in the X-axis direction and spatial frequency in the Y-axis direction of the light field formed by the plurality of simulated point light sources, the light field transfer function of angular spectrum propagation is calculated; According to the complex amplitude and the light field transfer function, the light field distribution is calculated.

3. The method of designing according to claim 2, wherein, The step of calculating the complex amplitude of the light emitted by the plurality of simulated point light sources after passing through the current metasurface structure modulation comprises the following steps: According to the wave number and the distance from the plurality of simulated point light sources to the observation point, the initial complex amplitude of each simulated point light source is calculated; According to the initial complex amplitude and the phase distribution of the current metasurface structure, the complex amplitude is calculated.

4. The design method of claim 3, wherein, based on the propagation distance, wave number, light source center wavelength, spatial frequency in the X-axis direction and spatial frequency in the Y-axis direction of the light field formed by the plurality of simulated point light sources, the light field transfer function of angular spectrum propagation is calculated, specifically comprising: Calculate the product of the light source center wavelength and the first spatial frequency to obtain a first intermediate quantity; Calculate the product of the light source center wavelength and the second spatial frequency to obtain a second intermediate quantity; Based on the first intermediate quantity, the second intermediate quantity, the light field propagation distance and the wave number, the light field transfer function is calculated; the first spatial frequency is the spatial frequency of the light field in the X-axis direction, and the second spatial frequency is the spatial frequency of the light field in the Y-axis direction; And / or, according to the complex amplitude and the light field transfer function, the light field distribution is calculated, specifically comprising: ​ performing Fourier transform on the complex amplitude to obtain a transformed complex amplitude; calculating a product of the transformed complex amplitude and the optical field transfer function to obtain a transformed square distribution; performing inverse Fourier transform on the transformed square distribution to obtain the optical field distribution; and / or, calculating an initial complex amplitude of each of the plurality of simulated point light sources according to the wave number and the distance from the observation point to the plurality of simulated point light sources, specifically comprising: calculating a product of the wave number and the distance from the observation point to the plurality of simulated point light sources to obtain a third intermediate quantity; calculating a complex number of the third intermediate quantity to obtain a fourth intermediate quantity; calculating a ratio of the fourth intermediate quantity and the distance from the observation point to the plurality of simulated point light sources to obtain the initial complex amplitude; and / or, calculating the complex amplitude according to the initial complex amplitude and the phase distribution of the current metasurface structure, specifically comprising: calculating a complex number of the phase distribution of the current metasurface structure to obtain a complex phase distribution; calculating a product of the initial complex amplitude and the complex phase distribution to obtain the complex amplitude.

5. The method of claim 3, wherein, calculating the current evaluation value according to the phase distribution of the optical field distribution, specifically comprising: when the target beam angle deflection value is 0°, calculating the current evaluation value according to the number of sampling points in the observation plane, the actual phase value of each sampling point and the average phase value of all sampling points; when the target beam angle deflection value is not 0°, calculating the current evaluation value according to the number of sampling points in the observation plane, the ideal phase value of each sampling point and the actual phase value of each sampling point.

6. The design method according to any one of claims 1 to 5, characterized in that, in the step of adjusting the current phase coefficient according to the current evaluation value until the current preset iteration end condition is met, thereby obtaining the optimal phase distribution, if the current iteration number is greater than the preset number or the continuous evaluation value change amount is less than the preset value, it is determined that the current preset iteration end condition is met, and the current phase coefficient corresponding to the minimum value of all the current evaluation values is taken as the optimal phase coefficient of the optimal phase distribution; wherein, the continuous evaluation value change amount is the change amount of a continuous preset number of current evaluation values; and / or, the initial phase distribution simulates the phase distribution of the metasurface structure by using a binary phase surface, and the initial phase distribution satisfies the following polynomial: ； where R represents the normalized radius of the binary phase plane, is the radial position on the metasurface structure, m is the number of polynomials, is the phase coefficient, represents the target beam angle deflection value, represents the phase distribution function, is the light source center wavelength; and / or, the set angle is 50°-70°.

7. A preparation method of a Micro-LED device, comprising: providing a first Micro-LED array; sequentially preparing an aperture assembly and a metasurface structure on the first Micro-LED array; wherein the phase distribution of the metasurface structure is obtained by using the design method of any one of claims 1-6. 8.A Micro-LED device obtained by the preparation method of claim 7. comprising: a first Micro-LED array comprising a plurality of arrayed first light sources; an aperture assembly located above the first Micro-LED array and comprising a plurality of holes corresponding to the first light sources one by one, the first light sources being arranged in the corresponding holes; a metasurface structure located above the aperture assembly and used for regulating light after passing through the aperture assembly.

9. The Micro-LED device of claim 8, wherein, the Micro-LED device further comprises a second Micro-LED array, the second Micro-LED array comprising a plurality of second light sources arranged in an array, the second Micro-LED array being disposed around the first Micro-LED array; and / or, the metasurface structure comprises a substrate layer and a plurality of nano-pillars disposed on a side of the substrate layer distal to the aperture.

10. A design apparatus of a Micro-LED device, comprising a processor and a memory connected to each other, the processor being configured to execute a computer program stored in the memory to implement the design method of any one of claims 1-6.

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