Achromatic superlens design method and device

Abstract

The invention provides an achromatic superlens design method and device, and the method comprises the steps: carrying out the light field simulation of a target metasurface, and obtaining a simulation light field; the target metasurface is a plane where the pattern of the super lens is located; performing iterative optimization on the target metasurface according to the simulation light field and a preset target function, and taking the metasurface corresponding to the minimum preset target function as a final design pattern of the achromatic superlens; the preset objective function is irrelevant to the light wavelength and is used for representing the deviation between the simulation light field and the ideal light field; the ideal light field is related to the polar angle of the target metasurface in space, it is ensured that the super lens can achieve the characteristic that the focal length is not changed under different wavelengths, the high-quality achromatic effect is achieved, and the design efficiency and precision of the super lens are improved.

Description

Technical Field

[0001] The present invention relates to the technical field of metalenses, and in particular to an achromatic metalens design method and device. Background Art

[0002] Metasurface is an artificially fabricated material with special structures and properties. It controls and manipulates characteristics of electromagnetic waves such as amplitude, phase, polarization, and propagation direction by precisely arranging nanostructured units on a very thin plane. These nanostructured units can be metal or dielectric nanostructures of various shapes. Their combined action on incident electromagnetic waves can precisely regulate the propagation of electromagnetic waves, thereby achieving focusing and manipulation of light beams. The lens designed from metasurface material is called a metalens. Compared with traditional lenses, this lens is composed of sub-wavelength structures on the nanometer scale and has the great advantages of extremely thin thickness and light weight. However, light of different wavelengths has different refractive indices, which will cause different focusing effects for light of different wavelengths after passing through the lens, that is, chromatic aberration. For ordinary metalenses, due to their thinner thickness and higher transmittance, the chromatic aberration generated by light of different wavelengths after passing through the metalens is more obvious. Summary of the Invention

[0003] The present invention provides an achromatic metalens design method and device to solve the defect of chromatic aberration generated by light of different wavelengths after passing through the metalens in the prior art. The present invention ensures that the metalens can achieve the characteristic of constant focal length at different wavelengths, realizes a high-quality achromatic effect, and improves the efficiency and accuracy of metalens design.

[0004] The present invention provides an achromatic metalens design method, including: performing optical field simulation on a target metasurface to obtain a simulated optical field; iteratively optimizing the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum of the preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is spatially related to the polar angle of the target metasurface.

[0005] According to the achromatic metalens design method provided by the present invention, the function of the target metasurface is: , , wherein, is the function of the target metasurface, is the vacuum permittivity, is the permittivity of the functional sheet material, is the distribution function of the metalens material.

[0006] A method for designing an achromatic metalens according to the present invention, the preset objective function is: , , wherein, is the preset objective function, E is the simulated optical field, is the ideal optical field, is the integral region of the objective function, is the polar angle of the target metasurface, is the circumferential angle of the target metasurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the x direction, is the unit vector in the y direction, is the unit vector in the z direction, c is the speed of light.

[0007] A method for designing an achromatic metalens according to the present invention, the ideal optical field is only related to the polar angle of the target metasurface in space: , wherein, is the ideal optical field, is the polar angle of the target metasurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the y direction, is the unit vector in the z direction, c is the speed of light.

[0008] A method for designing an achromatic metalens according to the present invention, in the case of ignoring the polarization response of light, the distribution function of the metalens material is only related to the y value, the target metasurface is a one-dimensional pattern, and the two-dimensional pattern restored by circular symmetry of the one-dimensional pattern is used as the design pattern of the achromatic metalens.

[0009] A method for designing an achromatic metalens according to the present invention, the achromatic metalens is a double-layer structure, the lower layer is a quartz substrate, and the upper layer is an α-Si metalens pattern.

[0010] The present invention also provides an achromatic metalens design device, including: a simulation module for performing optical field simulation on a target metasurface to obtain a simulated optical field; an optimization module for iteratively optimizing the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum of the preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0011] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored on the memory and running on the processor. When the processor executes the computer program, the achromatic metalens design method described in any one of the above is implemented.

[0012] The present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, the achromatic metalens design method described in any one of the above is implemented.

[0013] The present invention also provides a computer program product, including a computer program. When the computer program is executed by a processor, the achromatic metalens design method described in any one of the above is implemented.

[0014] The achromatic metalens design method and device provided by the present invention. The method includes: performing optical field simulation on a target metasurface to obtain a simulated optical field; the target metasurface is the plane where the pattern of the metalens is located; iteratively optimizing the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum of the preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space, ensuring that the metalens can achieve the characteristic of constant focal length at different wavelengths, realizing a high-quality achromatic effect, and improving the efficiency and accuracy of metalens design. Description of the Drawings

[0015] In order to more clearly illustrate the technical solutions in the present invention or the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative efforts.

[0016] Figure 1 It is a schematic flowchart of an achromatic metalens design method provided by the present invention.

[0017] Figure 2 It is a schematic diagram of the metalens coordinate system provided by the present invention.

[0018] Figure 3 It is a schematic diagram of the principle of an achromatic metalens design method provided by the present invention.

[0019] Figure 4 One-dimensional provided by the present invention Corresponding two-dimensional simulation schematic diagram.

[0020] Figure 5 It is a schematic diagram of restoring a one-dimensional pattern to a two-dimensional pattern provided by the present invention.

[0021] Figure 6 It is a SEM image of the surface of the achromatic metalens prepared by the present invention.

[0022] Figure 7 It is a schematic diagram of the focal spot of a normal photograph provided by the present invention.

[0023] Figure 8 It is a schematic diagram of the Gaussian fitting result provided by the present invention.

[0024] Figure 9 It is a schematic diagram of the focal spot of a strongly overexposed photograph provided by the present invention.

[0025] Figure 10 It is a transverse optical field distribution slice diagram at different distances of the achromatic metalens at 1530nm, 1550nm, and 1565nm input light (from left to right), with strongly overexposed photographing, provided by the present invention.

[0026] Figure 11 It is a schematic diagram of the structure of an achromatic metalens design device provided by the present invention.

[0027] Figure 12 It is a schematic diagram of the structure of an electronic device provided by the present invention. Detailed implementation manners

[0028] To make the objectives, technical solutions, and advantages of the present invention clearer, the technical solutions in the present invention will be clearly and completely described below with reference to the accompanying drawings in the present invention. Apparently, the described embodiments are some, but not all, of the embodiments of the present invention. All other embodiments obtained by those of ordinary skill in the art without creative efforts based on the embodiments in the present invention belong to the scope of protection of the present invention.

[0029] A metasurface is a pattern with sub-wavelength feature sizes in a two-dimensional planar direction, thus being a device that can regulate light incident perpendicular to this plane. This pattern is etched from a complete functional sheet material, with the etched part becoming voids and the remaining part forming columnar or mesa-like structures. From the perspective of light incidence, the etched and unetched parts constitute a planar pattern. A lens designed using metasurface materials, namely a metalens, has the characteristics of being thin and light in weight compared to traditional optical lenses, and multiple lenses can be simplified into one or several layers of metasurface structures, which is conducive to the integration and miniaturization of the imaging lens system. However, a metalens will produce a large chromatic aberration, which will affect its use effect.

[0030] Please refer to Figure 1 , Figure 1 which is a schematic flow chart of a method for designing an achromatic metalens provided by the present invention.

[0031] Please refer to Figure 2 , Figure 2 which is a schematic diagram of the metalens coordinate system provided by the present invention.

[0032] Please refer to Figure 3 , Figure 3 which is a schematic principle diagram of a method for designing an achromatic metalens provided by the present invention.

[0033] The present invention provides a method for designing an achromatic metalens, including: 101: Conduct optical field simulation on the target metasurface to obtain a simulated optical field; the target metasurface is the plane where the pattern of the metalens is located.

[0034] As a preferred embodiment, the function of the target metasurface is: , , wherein, is the function of the target metasurface, is the vacuum permittivity, is the permittivity of the functional sheet material, is the distribution function of the metalens material.

[0035] In order to achieve an achromatic metalens with a constant focal length within a certain wavelength band, the present invention provides a method for designing an achromatic metalens. If the target is to design a metalens with a focal length of L , a radius of R , and a sheet thickness of h , then establish a metalens coordinate system, where the plane is the plane where the pattern of the metalens is located, is the incident light direction. Determine the focal length LIn the case of A point on the plane can also be represented by the full angle and polar angle coordinates representation.

[0036] After initializing the distribution function of the metasurface material a function of the target metasurface is constructed , and then three-dimensional FDTD simulation is performed to obtain the simulated optical field.

[0037] It should be explained that the basic principle of FDTD is to discretize the continuous space and time. In space, the simulation region is divided into small cells using the Yee grid; in time, the electric and magnetic fields are iteratively solved through time steps. This method allows the response at multiple frequencies to be calculated simultaneously at each time point, which is particularly important for the analysis of broadband signals. Forward FDTD simulation is a method for directly simulating the propagation and interaction of electromagnetic waves in space and time. It is based on Maxwell's equations and iteratively updates the values of the electric and magnetic field components at the next time step by discretizing space and time into grids and calculating the electric and magnetic field components at each grid point.

[0038] 102: Iteratively optimize the target metasurface according to the simulated optical field and the preset target function, and use the metasurface corresponding to the minimum of the preset target function as the design pattern of the final achromatic metalens; the preset target function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0039] As a preferred embodiment, the preset target function is: , , where is the preset target function, E is the simulated optical field, is the ideal optical field, is the integral region of the target function, is the polar angle of the target metasurface, is the full angle of the target metasurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the x direction, is the unit vector in the y direction, is the unit vector in the z direction, c is the speed of light.

[0040] In this embodiment, by calculating the preset target functionF Defined as the deviation between the simulated optical field and the ideal optical field, updated by the gradient descent method And iterate this process to make the objective function F Minimize. Is a space located behind the metasurface, and it is required that the influence of the evanescent field can be ignored here, so that the transmitted light can be accurately reflected.

[0041] It should be noted that the objective function corresponds to the time-domain response of an ideal lens, which means that the incident light forms a specific relative lag at different lateral distances after passing through the metasurface, thus achieving focusing.

[0042] Is the ideal optical field obtained according to the principles of light deflection and lag. Is a normalization factor used to ensure the conservation of the total energy of the electric field. Represents the time delay caused by the propagation of light in the medium. The vector part describes the distribution of the optical field in space.

[0043] As a preferred embodiment, the ideal optical field is only related to the polar angle of the target metasurface in space: , Wherein, Is the ideal optical field, Is the polar angle of the target metasurface, Is the electromagnetic field evolution time, Is the electric field amplitude of the incident light, Is the focal length, Is the unit vector in the y direction, Is the unit vector in the z direction, c Is the speed of light.

[0044] Please refer to Figure 4 , Figure 4 For the one-dimensional Two-dimensional simulation schematic diagram provided by the present invention.

[0045] Please refer to Figure 5 , Figure 5 For the schematic diagram of restoring the one-dimensional pattern to a two-dimensional pattern provided by the present invention.

[0046] As a preferred embodiment, when ignoring the polarization response of light, the distribution function of the hyperlens material is only related to the y value, the target metasurface is a one-dimensional pattern, and the two-dimensional pattern restored from the one-dimensional pattern by circular symmetry is used as the design pattern of the achromatic hyperlens.

[0047] In order to further reduce the simulation time, in this embodiment, the polarization response of light is ignored, that is, the metasurface has an approximate effect on light with different polarization directions. Then, in the ideal optical field, only In this case, the ideal light field only depends on the polar angle of the target metasurface in space This corresponds to the optimized material distribution function only depending on y, that is , in this case, a two-dimensional simulation approximation can be used to optimize one-dimensional , corresponding to obtaining a one-dimensional metasurface pattern . Then it is restored to a two-dimensional pattern through circular symmetry, and the two-dimensional pattern is used as the design pattern of the achromatic metalens. Among them, the circular symmetry relation is .

[0048] The simulation time of FDTD is proportional to the number of grids into which the simulation region is divided. Let the simulation grid size be . Then before using the approximation, the number of simulation grids . After using the approximation, the number of simulation grids . Considering that for a typical metalens, L is in the order of magnitude, R is in the order of hundreds to the mm order of magnitude, the simulation time is mainly determined by R , so the order reduction of R will greatly reduce the simulation time.

[0049] This method is applicable to any wavelength , requiring , and has strong universality.

[0050] As a preferred embodiment, the achromatic metalens is a bilayer structure, with a quartz substrate in the lower layer and an α-Si metalens pattern in the upper layer.

[0051] The method of the present invention greatly reduces the simulation time while the optimized metalens has good performance. In this embodiment, the actually fabricated x-achromatic metalens is a bilayer structure, with a quartz substrate in the lower layer and an α-Si metalens pattern in the upper layer.

[0052] The relevant structural parameters are: .

[0053] The preparation process can be as follows: First, deposit 800 nm thick α-Si on a quartz substrate by plasma-enhanced chemical vapor deposition (PECVD, Plasma Enhanced Chemical Vapor Deposition), and then deposit a 100 nm thick Cr metal hard mask layer on the α-Si by electron beam evaporation. In particular, in order to avoid the complex and difficult Cr stripping operation in the subsequent process, a 100 nm thick SiO2 layer is grown on the Cr layer as an additional hard mask. Then, a layer of photoresist (ZEON ZEP520A) is spun on the sample and exposed by electron beam lithography. Then, the pattern is transferred from the electron beam etchant to the SiO2 layer by reactive ion etching, and then the Cr layer is etched using ICP-RIE etching in the presence of the SiO2 mask, and the etched pattern is the pattern designed by accompanying optimization.

[0054] Please refer to Figure 6 , Figure 6 which is the SEM image of the surface of the achromatic metalens prepared according to the present invention.

[0055] It can be seen that the light gray area under the electron microscope corresponds to the α-Si pattern retained after etching.

[0056] Please refer to Figure 7 , Figure 7 which is the schematic diagram of the focal spot of the normal photograph provided by the present invention.

[0057] Please refer to Figure 8 , Figure 8 which is the schematic diagram of the Gaussian fitting result provided by the present invention.

[0058] It can be seen that the fitting corresponds to Figure 7 the focal spot shown in .

[0059] Please refer to Figure 9 , Figure 9 which is the schematic diagram of the focal spot of the strongly overexposed photograph provided by the present invention.

[0060] It can be seen that, compared with Figure 7 the focal spot of the normal photograph, Figure 9 the visible focal spot of the strongly overexposed photograph has higher quality.

[0061] Please refer to Figure 10 , Figure 10 which is the cross-sectional view of the lateral light field distribution of the achromatic metalens at different distances for the input light of 1530 nm, 1550 nm, and 1565 nm (from left to right) provided by the present invention, with strong overexposure photography.

[0062] It can be seen thatFigure 10 It generally conforms to the characteristics of the focused light field of a general lens.

[0063] Comparing the simulation time, the running hardware is a 40-core Intel Xeon Gold 6242R processor. The design time of the prior art method > 10h, and the design time of the method of the present invention ~ 10s.

[0064] In the performance test of the metalens, the focus spot size (the smaller the better), the relative change rate of the focal length at different wavelengths (the smaller the better), and the quality of the focused light field (the more concentrated the better) are mainly tested.

[0065] Focus spot size: Under the input light of 1550nm, the diameter of the focus spot on the CCD is Gaussian-fitted. The focus spot diameter of the prior art ~ 5 . The focus spot diameter of the present invention is 4.24 , and this diameter is basically unchanged at different wavelengths.

[0066] The relative change rate of the focal length of the prior art > 10%. The relative change rate of the focal length of the present invention < 1%, and it is basically unchanged at different wavelengths.

[0067] In summary, through testing, it is verified that the design method proposed by the present invention can greatly reduce the design time and design an achromatic metalens with good performance.

[0068] Next, the achromatic metalens design device provided by the present invention will be described. The achromatic metalens design device described below can be mutually corresponding and referred to with the achromatic metalens design method described above.

[0069] Please refer to Figure 11 , Figure 11 , which is a schematic structural diagram of an achromatic metalens design device provided by the present invention.

[0070] The present invention also provides an achromatic metalens design device, including: a simulation module 1101, configured to perform optical field simulation on a target metasurface to obtain a simulated optical field; an optimization module 1102, configured to perform iterative optimization on the target metasurface according to the simulated optical field and a preset objective function, and use the metasurface corresponding to the minimum of the preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0071] The present invention ensures that the metalens can achieve the characteristic of constant focal length at different wavelengths, realizes a high-quality achromatic effect, and improves the efficiency and accuracy of metalens design.

[0072] As a preferred embodiment, the function of the target metasurface is: , , Among them, is a function of the target metasurface, is the vacuum permittivity, is the permittivity of the functional sheet, is the distribution function of the metalens material.

[0073] As a preferred embodiment, the preset objective function is: , , Among them, is the preset objective function, E is the simulated optical field, is the ideal optical field, is the integral region of the objective function, is the polar angle of the target metasurface, is the circumferential angle of the target metasurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the x direction, is the unit vector in the y direction, is the unit vector in the z direction, c is the speed of light.

[0074] As a preferred embodiment, the ideal optical field is only related to the polar angle of the target metasurface in space: , Among them, is the ideal optical field, is the polar angle of the target metasurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the y direction, is the unit vector in the z direction, c is the speed of light.

[0075] As a preferred embodiment, in the case of ignoring the polarization response of light, the distribution function of the metalens material is only related to the y value, the target metasurface is a one-dimensional pattern, and the two-dimensional pattern restored by circular symmetry of the one-dimensional pattern is used as the design pattern of the achromatic metalens.

[0076] As a preferred embodiment, the achromatic metalens is a double-layer structure, the lower layer is a quartz substrate, and the upper layer is an α-Si metalens pattern.

[0077] Figure 12 The structural schematic diagram of an electronic device is exemplified, as Figure 12 shown. The electronic device may include: a processor 1201, a communications interface 1202, a memory 1203, and a communication bus 1204. Among them, the processor 1201, the communications interface 1202, and the memory 1203 complete mutual communication through the communication bus 1204. The processor 1201 may call the logical instructions in the memory 1203 to execute an achromatic metalens design method, and the method includes: performing optical field simulation on a target metasurface to obtain a simulated optical field; performing iterative optimization on the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0078] In addition, when the logical instructions in the above-mentioned memory 1203 are implemented in the form of software functional units and sold or used as independent products, they may be stored in a computer-readable storage medium. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art, or a part of the technical solution, may be embodied in the form of a software product. The computer software product is stored in a storage medium and includes several instructions for causing a computer device (which may be a personal computer, a server, or a network device, etc.) to execute all or part of the steps of the methods described in various embodiments of the present invention. The foregoing storage medium includes: various media such as a USB flash drive, a mobile hard disk, a read-only memory (ROM, Read-Only Memory), a random access memory (RAM, Random Access Memory), a magnetic disk, or an optical disc that can store program codes.

[0079] On the other hand, the present invention also provides a computer program product. The computer program product includes a computer program. The computer program can be stored on a non-transitory computer-readable storage medium. When the computer program is executed by a processor, the computer can execute the achromatic metalens design method provided by the above-mentioned various methods. The method includes: performing optical field simulation on a target metasurface to obtain a simulated optical field; performing iterative optimization on the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0080] In another aspect, the present invention also provides a non-transitory computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the achromatic metalens design method provided by the above-mentioned various methods. The method includes: performing optical field simulation on a target metasurface to obtain a simulated optical field; iteratively optimizing the target metasurface according to the simulated optical field and a preset objective function, and taking the metasurface corresponding to the minimum of the preset objective function as the design pattern of the final achromatic metalens; the preset objective function is independent of the optical wavelength and is used to characterize the deviation between the simulated optical field and the ideal optical field; the ideal optical field is related to the polar angle of the target metasurface in space.

[0081] The device embodiments described above are merely illustrative. The units described as separate components may or may not be physically separated. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed to multiple network units. Some or all of the modules can be selected according to actual needs to achieve the purpose of the solution of this embodiment. Those of ordinary skill in the art can understand and implement it without creative efforts.

[0082] Through the description of the above embodiments, those skilled in the art can clearly understand that each embodiment can be implemented by means of software plus a necessary general hardware platform, and of course, it can also be implemented by hardware. Based on this understanding, the above technical solution, in essence, or the part that contributes to the prior art, can be embodied in the form of a software product. The computer software product can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disc, etc., and includes several instructions for causing a computer device (which can be a personal computer, a server, or a network device, etc.) to execute the methods described in each embodiment or some parts of the embodiments.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or equivalently replace some of the technical features. These modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for designing an achromatic metalens, characterized in that: include: Performing light field simulation on the target metasurface to obtain a simulated light field; The target metasurface is the plane where the pattern of the metalens is located; The target metasurface is iteratively optimized according to the simulated light field and the preset objective function, and the metasurface corresponding to the minimum of the preset objective function is used as the final design pattern of the achromatic metalens; the preset objective function is independent of the wavelength of light and is used to characterize the deviation between the simulated light field and the ideal light field; the ideal light field is spatially related to the polar angle of the target metasurface.

2. The achromatic metalens design method according to claim 1, characterized in that: The function of the target hypersurface is: ， ， in, is the function of the target hypersurface, is the dielectric constant of vacuum, is the dielectric constant of the functional sheet, is the distribution function of the superlens material.

3. The achromatic metalens design method according to claim 1, characterized in that: The preset objective function is: ， ， in, is the preset objective function, E is the simulated light field, is the ideal light field, is the integration region of the objective function, is the polar angle of the target hypersurface, is the circumference angle of the target hypersurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the x direction, is the unit vector in the y direction, is the unit vector in the z direction, c The speed of light.

4. The achromatic metalens design method according to claim 1, characterized in that: The ideal light field is spatially only related to the polar angle of the target metasurface: ， in, is the ideal light field, is the polar angle of the target hypersurface, is the electromagnetic field evolution time, is the electric field amplitude of the incident light, is the focal length, is the unit vector in the y direction, is the unit vector in the z direction, c The speed of light.

5. The achromatic metalens design method according to claim 2, characterized in that: When the polarization response of light is ignored, the distribution function of the metalens material is only related to the y value, the target metasurface is a one-dimensional pattern, and the two-dimensional pattern restored from the one-dimensional pattern by circular symmetry is used as the design pattern of the achromatic metalens.

6. The achromatic metalens design method according to any one of claims 1 to 5, characterized in that: The achromatic superlens is a double-layer structure, the lower layer is a quartz substrate, and the upper layer is an α-Si superlens pattern.

7. An achromatic metalens design device, characterized in that: include: A simulation module, used for performing light field simulation on the target metasurface to obtain a simulated light field; An optimization module is used to iteratively optimize the target metasurface according to the simulated light field and a preset objective function, and use the pattern corresponding to the minimum of the preset objective function as the final design pattern of the achromatic metalens; the preset objective function is independent of the wavelength of light and is used to characterize the deviation between the simulated light field and the ideal light field; the ideal light field is spatially related to the polar angle of the target metasurface.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the achromatic metalens design method according to any one of claims 1 to 6 is implemented.

9. A non-transitory computer-readable storage medium having a computer program stored thereon, characterized in that: When the computer program is executed by a processor, the achromatic metalens design method according to any one of claims 1 to 6 is implemented.

10. A computer program product, comprising a computer program, characterized in that When the computer program is executed by a processor, the achromatic metalens design method according to any one of claims 1 to 6 is implemented.

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