A metasurface array, an optical module having the same, and a method for determining geometric parameters

Abstract

The present disclosure provides a metasurface array and an optical module and a method for determining geometric parameters having the same, and relates to the technical field of optoelectronic devices. The metasurface array includes a plurality of optical units, and the geometric parameters of the optical units are matched with the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase; the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions; the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions. The use of the metasurface array disclosed in the present disclosure can effectively increase the speckle density, while improving the accuracy and reliability of subsequent depth information calculation.

Description

Technical Field

[0001] The present disclosure generally relates to the technical field of optoelectronic devices, and specifically relates to a metasurface array and an optical module having the same, and a method for determining geometric parameters. Background Art

[0002] The speckle structured light 3D sensor obtains the depth information of the object by projecting a specially coded speckle pattern and capturing its reflection deformation, that is, calculating the pixel deformation in combination with an image matching algorithm. Specifically, the speckle structured light image matching algorithm first uses the calibrated planar speckle pattern as a reference image, then selects an image block based on a single pixel in the reflection image, and searches for a matching image block on the reference image, and finally calculates the offset of the two image blocks to obtain the disparity of the pixel, so that the depth value can be calculated based on the triangulation principle.

[0003] At present, the speckle density of the speckle structured light 3D sensor in the related technology is small, which causes undesirable phenomena such as "black holes" in the depth map, and subsequent correct image matching cannot be performed, which seriously affects the accuracy and reliability of 3D perception. Summary of the invention

[0004] In view of the above-mentioned defects or deficiencies in the related art, it is desired to provide a metasurface array and an optical module and a method for determining geometric parameters having the same, which can effectively increase the speckle density and improve the accuracy and reliability of subsequent depth information calculation.

[0005] In a first aspect, the present disclosure provides a metasurface array, wherein the metasurface array comprises a plurality of optical units, wherein the material of the optical units comprises any one of silicon-on-insulator material, SiO2-Si material, SiO2-SiN material and GaAs material,

[0006] The geometric parameters of the optical unit are matched with the two-dimensional phase distribution corresponding to light in different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. The corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical unit with different geometric parameters under the conditions of the incidence of light in different polarization directions. The corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical unit with different geometric parameters under the conditions of the incidence of light in different polarization directions.

[0007] Optionally, in some embodiments of the present disclosure, the light in different polarization directions includes light in a first polarization direction and light in a second polarization direction, wherein the first polarization direction and the second polarization direction are perpendicular to each other.

[0008] Optionally, in some embodiments of the present disclosure, the two-dimensional phase distribution is obtained by performing holographic phase extraction on a target speckle distribution pattern.

[0009] Optionally, in some embodiments of the present disclosure, the target speckle distribution pattern includes a random speckle distribution pattern or a uniform speckle distribution pattern.

[0010] Optionally, in some embodiments of the present disclosure, the geometric parameters of the optical unit include a length range of 50 nm to 450 nm, a width range of 50 nm to 450 nm, and a height of 750 nm.

[0011] Optionally, in some embodiments of the present disclosure, the shape of the optical unit includes any one of a cylindrical structure and a prismatic structure.

[0012] In a second aspect, the present disclosure provides an optical module, comprising a light source, a collimating lens, a polarizer, and a metasurface array as described in any one of the first aspects, which are arranged in sequence along the direction of the outgoing light.

[0013] Optionally, in some embodiments of the present disclosure, the light source is a vertical cavity surface emitting laser.

[0014] In a third aspect, the present disclosure provides a method for determining geometric parameters of optical units of a metasurface array, the method being used for the metasurface array described in any one of the first aspects, the method comprising:

[0015] According to the target speckle distribution patterns of light in different polarization directions, respectively determining the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns;

[0016] According to the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase, the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns is matched respectively to obtain the geometric parameters of each of the optical units; the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of the incident light in different polarization directions; the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of the incident light in different polarization directions.

[0017] Optionally, in some embodiments of the present disclosure, the corresponding relationship between the geometric parameter and the transmittance and the corresponding relationship between the geometric parameter and the transmission phase are matched with the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns to obtain the geometric parameters of each of the optical units, including:

[0018] In the corresponding relationship between each geometric parameter and transmittance, respectively determine the geometric parameter region range where the transmittance is greater than the transmittance threshold;

[0019] In the corresponding relationship between each geometric parameter and the transmission phase, the transmission phase distribution within the geometric parameter region is extracted respectively, and the transmission phase distribution covers 0 to 2π;

[0020] The magnitudes of the two-dimensional phase in the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns and the transmission phase in the transmission phase distribution are respectively compared, and when the comparison result meets a preset threshold, the geometric parameter corresponding to the transmission phase is determined as the geometric parameter of the optical unit.

[0021] It can be seen from the above technical solutions that the present disclosure has the following advantages:

[0022] The present disclosure provides a metasurface array and an optical module and a method for determining geometric parameters having the same. The metasurface array includes a plurality of optical units, and the geometric parameters of the optical units are matched with the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. Among them, the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions, and the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions. Since the metasurface array integrates the two-dimensional phase distribution corresponding to light of different polarization directions, the metasurface can be used to accurately control the phase and other characteristics of the incident electromagnetic wave on a subwavelength scale, and can generate mutually superimposed speckle distribution maps in the far field, effectively increasing the speckle density, while greatly improving the accuracy of subsequent depth information calculation, and having strong reliability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Other features, objects and advantages of the present disclosure will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0024] Figure 1 A schematic diagram of the structure of a metasurface array provided in an embodiment of the present disclosure;

[0025] Figure 2 A target speckle distribution diagram corresponding to a first polarization direction provided in an embodiment of the present disclosure;

[0026] Figure 3 A target speckle distribution diagram corresponding to a second polarization direction provided in an embodiment of the present disclosure;

[0027] Figure 4 A schematic diagram of a two-dimensional phase distribution corresponding to a first polarization direction provided in an embodiment of the present disclosure;

[0028] Figure 5A schematic diagram of a two-dimensional phase distribution corresponding to a second polarization direction provided in an embodiment of the present disclosure;

[0029] Figure 6 A schematic diagram of the structure of an optical module provided in an embodiment of the present disclosure;

[0030] Figure 7 A schematic diagram of the far-field structured light speckle under 0° polarization incidence provided by an embodiment of the present disclosure;

[0031] Figure 8 A schematic diagram of the far-field structured light speckle under 90° polarized incidence provided by an embodiment of the present disclosure;

[0032] Fig. 9 A schematic diagram of the far-field structured light speckle of a polarizer provided in an embodiment of the present disclosure under the condition of 45° polarized incidence;

[0033] Fig.10 A structural block diagram of an electronic device provided in an embodiment of the present disclosure;

[0034] Fig.11 A schematic flow chart of a method for determining geometric parameters of an optical unit of a metasurface array provided in an embodiment of the present disclosure;

[0035] Fig.12 A schematic diagram of the structure of an optical unit provided in an embodiment of the present disclosure;

[0036] Fig.13 The embodiment of the present disclosure provides a correspondence between the transmittance of an optical unit and a geometric parameter under the incidence of light in a first polarization direction, and a correspondence between the transmission phase of an optical unit and a geometric parameter, wherein Fig.13 (a) represents the corresponding relationship between the transmittance and geometric parameters of the optical unit under the first polarization direction of light incident, Fig.13 (b) represents the corresponding relationship between the transmission phase and the geometric parameters of the optical unit under the incidence of light in the first polarization direction;

[0037] Fig.14 The embodiment of the present disclosure provides a correspondence between the transmittance of the optical unit and the geometric parameters under the incident light of the second polarization direction and a correspondence between the transmission phase of the optical unit and the geometric parameters, wherein Fig.14 (a) represents the corresponding relationship between the transmittance and geometric parameters of the optical unit under the second polarization direction of light incident, Fig.14 (b) shows the correspondence between the transmission phase and geometric parameters of the optical unit when light in the second polarization direction is incident.

[0038] Reference numerals:

[0039] 1-metasurface array, 11-optical unit, 2-optical module, 21-light source, 22-collimating lens, 23-polarizer, 3-electronic device. DETAILED DESCRIPTION

[0040] In order to enable those skilled in the art to better understand the disclosed solution, the technical solution in the disclosed embodiment will be clearly and completely described below in conjunction with the drawings in the disclosed embodiment. Obviously, the described embodiment is only a part of the disclosed embodiment, not all of the embodiments. Based on the embodiments in the disclosed embodiment, all other embodiments obtained by ordinary technicians in the field without creative work are within the scope of protection of the disclosed embodiment.

[0041] The terms "first", "second", "third", "fourth", etc. (if any) in the specification and claims of the present disclosure and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the numbers used in this way can be interchanged where appropriate, so that the embodiments of the present disclosure described can be implemented in sequences other than those illustrated or described herein.

[0042] In addition, the terms "include" and "have" and any variations thereof are intended to cover non-exclusive inclusions. For example, a process, method, system, product, or apparatus that includes a series of steps or modules is not necessarily limited to those steps or modules explicitly listed, but may include other steps or modules not explicitly listed or inherent to these processes, methods, products, or apparatuses.

[0043] For ease of understanding and explanation, the following Figures 1 to 14 The metasurface array, the optical module having the metasurface array, and the method for determining the geometric parameters provided by the embodiments of the present disclosure are described in detail.

[0044] Please refer to Figure 1 , which is a structural schematic diagram of a metasurface array provided by an embodiment of the present disclosure. The metasurface array 1 includes a plurality of optical units 11, and the material of the optical unit 11 includes but is not limited to any one of silicon-on-insulator material (SOI), SiO2-Si material, SiO2-SiN material and GaAs material, and the geometric parameters of the optical unit 11 are matched with the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. Among them, the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions; and the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions.

[0045] Exemplarily, for example, light in different polarization directions includes light in a first polarization direction and light in a second polarization direction, wherein the first polarization direction and the second polarization direction are perpendicular to each other. For example, the light in the first polarization direction is light in an X polarization direction, and the light in the second polarization direction is light in a Y polarization direction. Assuming that the Z polarization direction differs from the X polarization direction by 45 degrees, the metasurface array 1 can be used to quickly generate a speckle distribution map C in the far field, which is a superposition of a target speckle distribution map A corresponding to the X polarization direction light and a target speckle distribution map B corresponding to the Y polarization direction light, thereby effectively increasing the speckle density of the structured light.

[0046] For another example, the two-dimensional phase distribution is obtained by performing holographic phase extraction on the target speckle distribution map, and the holographic phase extraction method includes but is not limited to the GS (Gerchberg-Saxton) algorithm and the iterative Fourier transform algorithm (Iterative Fourier Transform Algorithm, IFTA) and the like. For example, a target speckle distribution map A is constructed in the X polarization direction, and a target speckle distribution map B is constructed in the Y polarization direction, wherein the target speckle distribution map may include a random speckle distribution map or a uniform speckle distribution map. Taking random distribution as an example, the target speckle distribution map A corresponding to the X polarization direction is as follows: Figure 2 As shown in Figure 1, and the target speckle distribution diagram B corresponding to the Y polarization direction is shown in Figure 2. Figure 3 As shown. Further, the target speckle distribution map A and the target speckle distribution map B are respectively subjected to holographic phase extraction, and the corresponding two-dimensional phase distribution A ( Figure 4 ) and two-dimensional phase distribution B( Figure 5 ), where the phase values ​​are normalized.

[0047] For example, the geometric parameters of the optical unit 11 include a length range of 50 nm to 450 nm, a width range of 50 nm to 450 nm, and a height of 750 nm. Also, the shape of the optical unit 11 includes but is not limited to any one of a cylindrical structure and a prism structure, and the prism structure can be a cuboid, a pentagonal prism, a hexagonal prism, and the like.

[0048] The metasurface array provided by the embodiment of the present disclosure includes a plurality of optical units, and the geometric parameters of the optical units are matched with the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. Among them, the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions, and the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions. Since the metasurface array integrates the two-dimensional phase distribution corresponding to light of different polarization directions, the metasurface can be used to accurately control the phase and other characteristics of the incident electromagnetic wave on a subwavelength scale, and can generate mutually superimposed speckle distribution maps in the far field, effectively increasing the speckle density, while greatly improving the accuracy of subsequent depth information calculation, and having strong reliability.

[0049] As another aspect, the present disclosure provides an optical module. Figure 6 , which is a structural schematic diagram of an optical module provided by an embodiment of the present disclosure, wherein the optical module 2 comprises a light source 21, a collimating lens 22, a polarizer 23 and Figures 1 to 5 The optical module 2 of the corresponding embodiment of the metasurface array 1 can have broad application prospects in the fields of 3D perception, robot vision, augmented reality, autonomous driving, and electronic products based on 3D imaging. For example, in robot vision, increasing the speckle density can enhance the robot's ability to perceive the environment and achieve more accurate positioning and navigation; in augmented reality, high-density speckle patterns can provide richer depth information and enhance the fusion effect of virtual and reality; and in autonomous driving, accurate depth perception can provide more reliable environmental perception capabilities for the autonomous driving system.

[0050] Furthermore, the light source 21 can be a vertical cavity surface emitting laser (VCSEL). The advantage of such a setting is that the laser performance is excellent and the module is miniaturized. Exemplarily, the disclosed embodiment can add a Z polarization direction plate (for example, 45 degrees different from the X polarization direction) in front of the collimated VCSEL light source and project it onto the metasurface array 1, thereby generating a speckle distribution map C in the far field, which is a superposition of the target speckle distribution map A and the target speckle distribution map B, and effectively increasing the structured light speckle density. For example, under the condition of light incident in different polarization directions, the finite difference time-domain electromagnetic simulation software is used to perform a far-field simulation of the metasurface array 1. Figure 7 This is a schematic diagram of the far field of structured light speckle under 0° polarization incidence. Figure 8 is a schematic diagram of the far-field structured light speckle under 90° polarization incidence, and Fig. 9This is a schematic diagram of the far-field structured light speckle pattern under the condition of 45° polarized incident light. As can be seen from the figure, the far-field structured light speckle pattern under the condition of 0° polarized incident light is similar to Figure 2 The target speckle distribution diagram A corresponding to the X polarization direction is consistent with the structured light speckle far-field result under 90° polarization incidence. Figure 3 The target speckle distribution diagram B corresponding to the Y polarization direction in the middle remains consistent, and the far-field result of the structured light speckle under the 45° polarization incidence is the superposition of the two structured light speckles under the 0° and 90° polarization incidence conditions, thereby effectively increasing the density of the structured light speckle. In addition, the embodiment of the present disclosure can also rotate the polarizer 23 between 0° and 90° according to the speckle requirements of a specific scene, that is, continuously change between the X polarization direction and the Y polarization direction, thereby realizing the dynamic transformation of the structured light speckle pattern.

[0051] As another aspect, the present disclosure provides an electronic device. Fig.10 , which is a structural block diagram of an electronic device provided by an embodiment of the present disclosure, the electronic device 3 includes Figure 6 The optical module 2 of the corresponding embodiment.

[0052] It should be noted that, for the description of the same contents in this embodiment as those in other embodiments, reference can be made to the description in other embodiments and will not be repeated here.

[0053] Based on the above embodiments, the present disclosure provides a method for determining geometric parameters of optical units of a metasurface array, which can be used to Figures 1 to 5 The metasurface array 1 of the corresponding embodiment. Please refer to Fig.11 , which is a flow chart of a method for determining geometric parameters of an optical unit of a metasurface array provided by an embodiment of the present disclosure, the method comprising the following steps:

[0054] S101, according to target speckle distribution patterns of light in different polarization directions, respectively determine the two-dimensional phase distribution corresponding to each target speckle distribution pattern.

[0055] For example, the embodiment of the present disclosure can construct a target speckle distribution map A( Figure 2 As shown) and constructing the target speckle distribution map B in the Y polarization direction ( Figure 3 As shown in the figure), the X polarization direction and the Y polarization direction are perpendicular to each other. Then, the target speckle distribution pattern A and the target speckle distribution pattern B are iteratively calculated by the holographic phase extraction algorithm to obtain the two-dimensional phase distribution A corresponding to the target speckle distribution pattern A ( Figure 4 As shown in Figure 2, the two-dimensional phase distribution B corresponding to the target speckle distribution B ( Figure 5 shown).

[0056] S102, matching the two-dimensional phase distribution corresponding to each target speckle distribution map respectively according to the corresponding relationship between the geometric parameter and the transmittance and the corresponding relationship between the geometric parameter and the transmission phase, so as to obtain the geometric parameters of each optical unit.

[0057] Among them, the corresponding relationship between geometric parameters and transmittance represents the transmittance corresponding to optical units with different geometric parameters under the conditions of light incident in different polarization directions, while the corresponding relationship between geometric parameters and transmission phase represents the transmission phase corresponding to optical units with different geometric parameters under the conditions of light incident in different polarization directions.

[0058] Exemplarily, in obtaining the correspondence between geometric parameters and transmittance, the disclosed embodiment first determines the material and shape of the optical unit 11, and then performs electromagnetic simulation scanning on the geometric parameters of the optical unit 11 under different polarized light incident conditions to obtain the correspondence between the geometric parameters and the transmittance. Similarly, in obtaining the correspondence between the geometric parameters and the transmission phase, the material and shape of the optical unit 11 may be determined first, and then performs electromagnetic simulation scanning on the geometric parameters of the optical unit 11 under different polarized light incident conditions to obtain the correspondence between the geometric parameters and the transmission phase. The material of the optical unit 11 includes, but is not limited to, any one of silicon-on-insulator (SOI), SiO2-Si material, SiO2-SiN material, and GaAs material.

[0059] Taking SiO2-Si material as an example, the structure of the optical unit 11 in the embodiment of the present disclosure can be as follows: Fig.12 As shown in FIG. 1 , the nanorod material is Si and the substrate material is SiO2. Wherein, L represents the length of the nanorod, W represents the width of the nanorod, H represents the height of the nanorod, and P represents the lattice constant of the structural unit. For example, finite difference time-domain electromagnetic simulation software is used to Fig.12 The length and width parameters of the nanocolumns on the surface of the medium were scanned, that is, the background refractive index of the environment was set to 1, the lattice constant P was set to 500nm, and the height H of the nanocolumns was set to 750nm. The X-polarized light and the Y-polarized light with a wavelength of 940nm were used as the incident light sources, and the length L and width W of the nanocolumns were scanned in two dimensions. The scanning range was 50nm to 450nm, and the length L and width W of the nanocolumns were respectively obtained. Fig.13 The corresponding relationship between the transmittance of the optical unit and the geometric parameters under the X-polarization direction light incident and the corresponding relationship between the transmission phase of the optical unit and the geometric parameters are shown. Fig.14The corresponding relationship between the transmittance and geometric parameters of the optical unit under the Y-polarization direction light incident and the corresponding relationship between the transmission phase and geometric parameters of the optical unit are shown, where the transmittance range is 0 to 1 and the transmission phase range is -π to π. It can be seen from the figure that by changing the length and width of the structural unit, the transmission phase range of 0 to 2π can be fully covered under different polarization light incident conditions.

[0060] Furthermore, when matching the two-dimensional phase distribution, the disclosed embodiment first determines the geometric parameter region range where the transmittance is greater than the transmittance threshold in the corresponding relationship between each geometric parameter and the transmittance, wherein the transmittance thresholds corresponding to light in different polarization directions may be the same or different, and the higher the transmittance, the higher the efficiency of the emitted light and the better the imaging effect; then, in the corresponding relationship between each geometric parameter and the transmission phase, respectively extract the transmission phase distribution within the geometric parameter region range, and the transmission phase distribution covers 0 to 2π; then, respectively compare the size of the two-dimensional phase in the two-dimensional phase distribution corresponding to each target speckle distribution diagram with the transmission phase in the transmission phase distribution, and when the comparison result meets the preset threshold, that is, the two-dimensional phase in the two-dimensional phase distribution is close to the transmission phase in the transmission phase distribution, thereby determining that the geometric parameter corresponding to the transmission phase is the geometric parameter corresponding to the optical unit, that is, the optical unit size parameter of the micro-nano processed metasurface array 1. Finally, actual micro-nano processing is performed through electron beam lithography (EBL) and lift-off process to prepare. Figure 1 A partial schematic diagram of the polarization multiplexing metasurface array is shown, in which the white part is the metasurface nanocolumn optical unit obtained by matching the geometric parameters of the metasurface unit in the high transmittance area of ​​the X-polarization direction light and the Y-polarization direction light, so that it satisfies the two-dimensional phase distribution A and the two-dimensional phase distribution B respectively when the X-polarization direction light and the Y-polarization direction light are incident.

[0061] The method for determining the geometric parameters of optical units of a metasurface array provided in an embodiment of the present disclosure includes a plurality of optical units, and the geometric parameters of the optical units are matched with the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. Among them, the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions, and the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of light incident in different polarization directions. Since the metasurface array integrates the two-dimensional phase distribution corresponding to light of different polarization directions, the metasurface can be used to accurately control the phase and other characteristics of the incident electromagnetic wave on a subwavelength scale, and can generate mutually superimposed speckle distribution maps in the far field, effectively increasing the speckle density, while greatly improving the accuracy of subsequent depth information calculation, and having strong reliability.

[0062] The above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them. Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A metasurface array, characterized in that: The metasurface array includes a plurality of optical units, and the material of the optical units includes any one of silicon-on-insulator material, SiO2-Si material, SiO2-SiN material and GaAs material. The geometric parameters of the optical unit are obtained by matching the two-dimensional phase distribution corresponding to light of different polarization directions based on the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase. The corresponding relationship between the geometric parameter and the transmittance represents the transmittance corresponding to the optical unit with different geometric parameters under the conditions of light incident in different polarization directions; the corresponding relationship between the geometric parameter and the transmission phase represents the transmission phase corresponding to the optical unit with different geometric parameters under the conditions of light incident in different polarization directions; The light with different polarization directions includes light with a first polarization direction and light with a second polarization direction, wherein the first polarization direction and the second polarization direction are perpendicular to each other; The two-dimensional phase distribution is obtained by performing holographic phase extraction on the target speckle distribution diagram.

2. The metasurface array according to claim 1, characterized in that: The target speckle distribution pattern includes a random speckle distribution pattern or a uniform speckle distribution pattern.

3. The metasurface array according to claim 1, characterized in that: The geometric parameters of the optical unit include a length range of 50 nm to 450 nm, a width range of 50 nm to 450 nm, and a height of 750 nm.

4. The metasurface array according to any one of claims 1 to 3, characterized in that: The shape of the optical unit includes any one of a cylindrical structure and a prism structure.

5. An optical module, characterized in that: The optical module includes a light source, a collimating lens, a polarizer, and a metasurface array as described in any one of claims 1 to 4, which are arranged in sequence along the direction of the outgoing light.

6. The optical module according to claim 5, characterized in that: The light source is a vertical cavity surface emitting laser.

7. A method for determining geometric parameters of optical units of a metasurface array, characterized in that: The method is used for the metasurface array according to any one of claims 1 to 4, and the method comprises: According to the target speckle distribution patterns of light in different polarization directions, respectively determining the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns; According to the corresponding relationship between the geometric parameters and the transmittance and the corresponding relationship between the geometric parameters and the transmission phase, the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns is matched respectively to obtain the geometric parameters of each of the optical units; the corresponding relationship between the geometric parameters and the transmittance represents the transmittance corresponding to the optical units with different geometric parameters under the conditions of the incident light in different polarization directions; the corresponding relationship between the geometric parameters and the transmission phase represents the transmission phase corresponding to the optical units with different geometric parameters under the conditions of the incident light in different polarization directions.

8. The method according to claim 7, characterized in that According to the correspondence between the geometric parameter and the transmittance and the correspondence between the geometric parameter and the transmission phase, the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns is matched to obtain the geometric parameters of each of the optical units, including: In the corresponding relationship between each geometric parameter and transmittance, respectively determine the geometric parameter region range where the transmittance is greater than the transmittance threshold; In the corresponding relationship between each geometric parameter and the transmission phase, the transmission phase distribution within the geometric parameter region is extracted respectively, and the transmission phase distribution covers 0~2 ; The magnitudes of the two-dimensional phase in the two-dimensional phase distribution corresponding to each of the target speckle distribution patterns and the transmission phase in the transmission phase distribution are respectively compared, and when the comparison result meets a preset threshold, the geometric parameter corresponding to the transmission phase is determined as the geometric parameter of the optical unit.

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