A metasurface lens and a method for determining the parameters of the metasurface lens

Abstract

An embodiment of the present application provides a metasurface lens and a method for determining the parameters of the metasurface lens. The metasurface lens includes: a substrate and nano-microstructures; wherein, one side of the substrate is formed into a stepped disc structure that increases sequentially from the periphery to the center. The stepped disc structure includes at least one step, and a plurality of nano-microstructures are arranged on each step surface; each step and the plurality of nano-microstructures on its surface jointly perform dispersion; the plurality of nano-microstructures perform focusing. By increasing the dispersion of the incident light by at least one step included in the substrate, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens are increased, and a metasurface lens with a larger radius, a larger numerical aperture, and a larger bandwidth of the achromatic band is obtained.

Description

Technical Field

[0001] The present application relates to the field of optical imaging technology, and in particular, to a metasurface lens and a method for determining parameters of the metasurface lens. Background Art

[0002] A metasurface lens is a metasurface that realizes the imaging function of a lens. The metasurface lens includes a transparent substrate and a plurality of artificial nanostructures on the surface of the transparent substrate. Each artificial nanostructure can disperse incident light to introduce independent phase mutations, realize local regulation of the phase of the incident light, so that the phase distribution of the incident light at each position on the metasurface lens is the phase distribution corresponding to the focused wavefront, and finally realize the functions of focusing or imaging.

[0003] Compared with traditional optical lenses, the metasurface lens is a planar structure and has the advantages of being thin and light. However, an imaging system composed of only a single metasurface lens often has serious chromatic aberration, and its imaging quality cannot reach the same imaging quality as that of a traditional lens group. Therefore, the metasurface lens imaging system needs to achromatize the incident light whose wavelength belongs to the achromatic band, that is, reduce the chromatic aberration generated when the metasurface lens images the incident light whose wavelength belongs to the achromatic band.

[0004] In related technologies, achromatization of the incident light during imaging of the metasurface lens can be achieved by changing the radius of the metasurface lens, changing the numerical aperture of the metasurface lens, etc. The numerical aperture of the metasurface lens represents the size of the angle between the line connecting the focus of the metasurface lens and the edge of the metasurface lens and the horizontal line, and the numerical aperture of the metasurface lens is positively correlated with the radius of the metasurface lens.

[0005] However, the radius of the metasurface lens is negatively correlated with the bandwidth of the achromatic band, and the numerical aperture of the metasurface lens is also negatively correlated with the bandwidth of the achromatic band. That is, if the radius and numerical aperture of the metasurface lens are to be increased, the bandwidth of the achromatic band needs to be reduced. Therefore, restricted by this relationship, it is impossible to obtain a metasurface lens that simultaneously has a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band. Summary of the Invention

[0006] The purpose of the embodiments of the present application is to provide a metasurface lens and a method for determining parameters of the metasurface lens to obtain a metasurface lens that simultaneously has a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band. The specific technical solutions are as follows:

[0007] In the first aspect of the embodiments of the present application, first, a metasurface lens is provided, including: a substrate and nano-microstructures; wherein,

[0008] One side of the substrate is formed into a stepped disc structure that increases successively from the periphery to the center. The stepped disc structure includes at least one step, and a plurality of nano-microstructures are arranged on each step surface; the plurality of nano-microstructures on each step and the step surface together perform dispersion; the plurality of nano-microstructures perform focusing.

[0009] Optionally, the working wavelength band of the metasurface lens is the visible light band; the material of the substrate is a material that is transparent to visible light, and the material of the substrate includes at least one of the following materials: silica, quartz glass, fused quartz, flint glass, optical glass;

[0010] The material of the nano-microstructure is a material that is transparent to visible light, and the material of one nano-microstructure includes at least one of the following materials: silicon nitride, silica, tantalum pentoxide;

[0011] A visible light antireflection film is provided on the side of the substrate away from the nano-microstructure; and / or; a visible light antireflection film is provided on the side of the plurality of nano-microstructures away from the substrate.

[0012] Optionally, the working wavelength band of the metasurface lens is the infrared band, the material of the substrate is a material that is transparent to infrared light, and the material of the substrate includes at least one of the following materials: silicon-based glass materials, germanium-based glass materials, chalcogenide glass materials;

[0013] The material of the nano-microstructure is a material that is transparent to infrared light, and the material of one nano-microstructure includes at least one of the following materials: silicon-based glass materials, germanium-based glass materials, chalcogenide glass materials;

[0014] An infrared antireflection film is provided on the side of the substrate away from the nano-microstructure; and / or; an infrared antireflection film is provided on the side of the plurality of nano-microstructures away from the substrate.

[0015] Optionally, the structure of one nano-microstructure is any one of the following structures: cylinder, square column, cross, ring, square ring, cylinder inverse structure, square column inverse structure, cross inverse structure.

[0016] In the second aspect of the embodiments of the present application, a method for determining the parameters of a metasurface lens is provided, which is used to determine the parameters of the metasurface lens according to any one of the above first aspects. The method includes:

[0017] For each preset position of the metasurface lens for which parameters are to be determined, based on the preset radius and the preset working wavelength band of the metasurface lens, determine the required phase difference of the incident light of two target wavelengths within the preset working wavelength band at this preset position, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference;

[0018] For each nano microstructure, obtain the modulation phase difference of the incident light of the nano microstructure for the two target wavelengths from the microstructure database, and obtain the maximum value among the modulation phase differences corresponding to each nano microstructure as the maximum modulation phase difference;

[0019] Based on the maximum required phase difference and the maximum modulation phase difference, determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step;

[0020] For each step of the substrate, calculate the difference between the maximum value of the required phase differences corresponding to the preset positions in the step and the maximum modulation phase difference to obtain the substrate phase of the step;

[0021] For each preset position of the metasurface lens, calculate the microstructure phase of the nano microstructure at the preset position based on the required phase of the incident light of the two target wavelengths at the preset position and the substrate phase of the step to which the preset position belongs;

[0022] Determine the structural parameters of the nano microstructure that satisfies the microstructure phase corresponding to the preset position in the microstructure database to obtain the structural parameters of the nano microstructure at the preset position of the metasurface lens.

[0023] Optionally, the determining the required phase difference of the incident light of the two target wavelengths at the preset position within the preset working band based on the preset radius and the preset working band of the metasurface lens includes:

[0024] Calculate the required phases of the incident light of the two target wavelengths at the preset position within the preset working band according to the first preset formula;

[0025] Wherein, the first preset formula is:

[0026]

[0027] Wherein, represents the required phase, (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant;

[0028] Calculate the difference between the required phases of the incident light of the two target wavelengths at the preset position to obtain the required phase difference of the incident light of the two target wavelengths at the preset position.

[0029] Optionally, determining the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step based on the maximum required phase difference and the maximum modulation phase difference includes:

[0030] Calculating the quotient of the maximum required phase difference and the maximum modulation phase difference, and rounding up the calculation result to obtain the number of steps of the substrate;

[0031] For each step of the substrate, calculating the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step; where the coefficient corresponding to a step represents the position of the step in the substrate;

[0032] Determining the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate.

[0033] Optionally, calculating the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step includes:

[0034] Calculating the product of the maximum modulation phase difference and the coefficient corresponding to the step as the first phase parameter of the step;

[0035] Calculating the difference between the maximum required phase difference and the first phase parameter of the step to obtain the second phase parameter of the step;

[0036] Determining, from the preset positions of the metasurface lens, the preset position corresponding to the required phase difference that is the same as the second phase parameter of the step, to obtain the position of the edge of the step in the metasurface lens;

[0037] Determining the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and the center of the metasurface lens as the center of the circle, to obtain the diameter of the circular area to which the step belongs;

[0038] If the step is the highest step in the substrate, determining the diameter of the circular area to which the step belongs as the width of the step;

[0039] If the step is not the highest step in the substrate, calculating the difference between the radius of the circular area to which the step belongs and the radius of the circular area to which the upper adjacent step belongs to obtain the width of the step.

[0040] Optionally, determining the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate includes:

[0041] Based on a second preset formula, determine the height of the substrate at the step according to the substrate phase of the step and the refractive index of the material of the substrate.

[0042] Wherein, the second preset formula is:

[0043]

[0044] Wherein, represents the substrate phase of the step, n represents the refractive index of the material of the substrate, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at the step.

[0045] In the third aspect of the embodiments of the present application, a device for determining parameters of a metasurface lens is provided, which is used to determine the parameters of the metasurface lens described in any item of the first aspect above. The device includes:

[0046] A required phase difference determination module, configured to, for each preset position of the metasurface lens for which parameters are to be determined, based on the preset radius and preset working band of the metasurface lens, determine the required phase difference of the incident light of the two target wavelengths within the preset working band at the preset position, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference;

[0047] A modulation phase difference determination module, configured to, for each nano microstructure, obtain the modulation phase difference of the incident light of the two target wavelengths for the nano microstructure from a microstructure database, and obtain the maximum value among the modulation phase differences corresponding to each nano microstructure as the maximum modulation phase difference;

[0048] A substrate parameter determination module, configured to determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step based on the maximum required phase difference and the maximum modulation phase difference;

[0049] A substrate phase determination module, configured to, for each step of the substrate, calculate the difference between the maximum value among the required phase differences corresponding to each preset position in the step and the maximum modulation phase difference to obtain the substrate phase of the step;

[0050] A microstructure phase determination module, configured to, for each preset position of the metasurface lens, calculate the microstructure phase of the nano microstructure at the preset position based on the required phase of the incident light of the two target wavelengths at the preset position and the substrate phase of the step to which the preset position belongs;

[0051] A microstructure parameter determination module, configured to determine the structural parameters of the nano microstructure that satisfies the microstructure phase corresponding to the preset position in the microstructure database, and obtain the structural parameters of the nano microstructure at the preset position of the metasurface lens.

[0052] Optionally, the required phase difference determination module is specifically configured to:

[0053] Calculate the required phases of the incident lights of two target wavelengths within the preset working band at the preset position according to a first preset formula;

[0054] Wherein, the first preset formula is:

[0055]

[0056] Wherein, represents the required phase, (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant;

[0057] Calculate the difference between the required phases of the incident lights of the two target wavelengths at the preset position to obtain the required phase difference between the incident lights of the two target wavelengths at the preset position.

[0058] Optionally, the substrate parameter determination module is specifically configured to:

[0059] Calculate the quotient of the maximum required phase difference and the maximum modulation phase difference, and round up the calculation result to obtain the number of steps of the substrate;

[0060] For each step of the substrate, calculate the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step; wherein, the coefficient corresponding to a step represents the position of the step in the substrate;

[0061] Determine the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate.

[0062] Optionally, the substrate parameter determination module is specifically configured to:

[0063] Calculate the product of the maximum modulation phase difference and the coefficient corresponding to the step as the first phase parameter of the step;

[0064] Calculate the difference between the maximum required phase difference and the first phase parameter of the step to obtain the second phase parameter of the step;

[0065] Determine, from the preset positions of the metasurface lens, the preset position corresponding to the required phase difference that is the same as the second phase parameter of the step to obtain the position of the edge of the step in the metasurface lens;

[0066] Determine the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and the center of the metasurface lens as the center of the circle, to obtain the diameter of the circular area to which the step belongs;

[0067] If the step is the highest step in the substrate, determine that the diameter of the circular area to which the step belongs is the width of the step;

[0068] If the step is not the highest step in the substrate, calculate the difference between the radius of the circular area to which the step belongs and the radius of the circular area to which the upper adjacent step belongs, to obtain the width of the step.

[0069] Optionally, the substrate parameter determination module is specifically configured to:

[0070] Based on a second preset formula, determine the height of the substrate at the step according to the substrate phase of the step and the refractive index of the material of the substrate;

[0071] Wherein, the second preset formula is:

[0072]

[0073] Wherein, represents the substrate phase of the step, n represents the refractive index of the material of the substrate, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at the step.

[0074] In a fourth aspect of the embodiments of the present application, an electronic device is provided, including:

[0075] A memory for storing a computer program;

[0076] A processor, when executing the program stored on the memory, implements the method for determining the parameters of the metasurface lens according to any one of the above second aspects.

[0077] In a fifth aspect of the embodiments of the present application, a computer-readable storage medium is provided. The computer-readable storage medium stores a computer program, and when the computer program is executed by a processor, the method for determining the parameters of the metasurface lens according to any one of the above second aspects is implemented.

[0078] The embodiments of the present application also provide a computer program product containing instructions, which when running on a computer, causes the computer to execute the method for determining the parameters of the metasurface lens according to any one of the above second aspects.

[0079] Advantages of the embodiments of the present application:

[0080] A metasurface lens provided by an embodiment of the present application includes: a substrate and nano-microstructures; wherein, one side of the substrate is formed into a stepped disc structure that gradually increases from the periphery to the center, the stepped disc structure includes at least one step, and a plurality of nano-microstructures are arranged on each step surface; each step and the plurality of nano-microstructures on its surface jointly perform dispersion; and the plurality of nano-microstructures perform focusing.

[0081] Based on the metasurface lens provided by the embodiment of the present application, the steps of the metasurface lens and the plurality of nano-microstructures on its surface jointly perform dispersion on the incident light, that is, the dispersion of the incident light by the metasurface lens is: the sum of the dispersion of the incident light by the substrate and the dispersion of the incident light by the nano-microstructures. Since the substrate of the metasurface lens is a stepped disc structure that gradually increases from the periphery to the center, that is, the substrate includes a plurality of steps, the dispersion of the incident light by the substrate is increased, and thus the dispersion of the incident light by the metasurface lens is increased. Moreover, the dispersion of the incident light by the metasurface lens is positively correlated with the radius of the metasurface lens, the dispersion of the incident light by the metasurface lens is positively correlated with the numerical aperture of the metasurface lens, and the dispersion of the incident light by the metasurface lens is positively correlated with the bandwidth of the achromatic band of the metasurface lens. Then, when the dispersion of the incident light by the metasurface lens is increased, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens can also be increased, that is, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0082] Of course, it is not necessary for any product or method implementing the present application to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0083] In order to more clearly illustrate the technical solutions in the embodiments of the present application 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 only some embodiments of the present application, and those of ordinary skill in the art can also obtain other embodiments based on these drawings.

[0084] Figure 1 The first structural diagram of the metasurface lens provided by the embodiment of the present application;

[0085] Figure 2 is Figure 1 a working principle diagram of the metasurface lens shown;

[0086] Figure 3 is Figure 1 a parameter schematic diagram of the metasurface lens shown;

[0087] Figure 4 The second structural diagram of the metasurface lens provided by the embodiment of the present application;

[0088] Figure 5 The third structural diagram of the metasurface lens provided by the embodiment of the present application;

[0089] Figure 6 A top view of the fourth metasurface lens provided by the embodiment of the present application;

[0090] Figure 7(a) is the fifth structural diagram of the metasurface lens provided by the embodiment of the present application;

[0091] Figure 7(b) is the sixth structural diagram of the metasurface lens provided by the embodiment of the present application;

[0092] Figure 8(a) is the structural diagram of the cross-shaped nanostructure provided by the embodiment of the present application;

[0093] Figure 8(b) is the structural diagram of the ring-shaped nanostructure provided by the embodiment of the present application;

[0094] Figure 8(c) is the structural diagram of the square-ring-shaped nanostructure provided by the embodiment of the present application;

[0095] Figure 8(d) is the structural diagram of the cylindrical anti-structure-shaped nanostructure provided by the embodiment of the present application;

[0096] Figure 8(e) is the structural diagram of the square-column anti-structure-shaped nanostructure provided by the embodiment of the present application;

[0097] Figure 9 The first flow chart of the method for determining the parameters of the metasurface lens provided by the embodiment of the present application;

[0098] Figure 10 A curve diagram of the corresponding relationship between each preset position of the metasurface lens provided by the embodiment of the present application and the required phase of the incident light at each preset position;

[0099] Figure 11 The second flow chart of the method for determining the parameters of the metasurface lens provided by the embodiment of the present application;

[0100] Figure 12 A curve diagram of the corresponding relationship between each preset position of the metasurface lens provided by the embodiment of the present application and the substrate phase of the incident light at each preset position;

[0101] Figure 13 A curve diagram of the corresponding relationship between each preset position of the metasurface lens provided by the embodiment of the present application and the microstructure phase of the nanostructure at each preset position;

[0102] Figure 14 The third flow chart of the method for determining the parameters of the metasurface lens provided by the embodiment of the present application;

[0103] Figure 15A graph showing the correspondence between each preset position of the metasurface lens provided in the embodiments of the present application and the PSF (Point Spread Function) of the metasurface lens in the x direction;

[0104] Figure 16 A graph showing the correspondence between the preset positions along the principal optical axis direction of the metasurface lens provided in the embodiments of the present application and the PSF of the metasurface lens along the principal optical axis direction;

[0105] Figure 17 A graph showing the correspondence between the wavelength of the incident light provided in the embodiments of the present application and the focal length of the metasurface lens;

[0106] FIG. 18(a) is a schematic diagram of the PSF of incident light with a wavelength of 8 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0107] FIG. 18(b) is a schematic diagram of the PSF of incident light with a wavelength of 9 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0108] FIG. 18(c) is a schematic diagram of the PSF of incident light with a wavelength of 10 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0109] FIG. 18(d) is a schematic diagram of the PSF of incident light with a wavelength of 11 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0110] FIG. 18(e) is a schematic diagram of the PSF of incident light with a wavelength of 12 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0111] FIG. 18(f) is a schematic diagram of the PSF of incident light with a wavelength of 13 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0112] FIG. 18(g) is a schematic diagram of the PSF of incident light with a wavelength of 14 μm at each preset position of the metasurface lens provided in the embodiments of the present application;

[0113] Figure 19 A graph showing the correspondence between the wavelength of the incident light provided in the embodiments of the present application and the focusing efficiency of the metasurface lens;

[0114] Figure 20 A structural diagram of the parameter determination device of the metasurface lens provided in the embodiments of the present application;

[0115] Figure 21 A structural diagram of the electronic device provided in the embodiments of the present application;

[0116] Description of the drawings: 1 - Substrate; 11 - Step; 12 - Step; 13 - Step; 14 - Step; 2 - Nanomicrostructure; 21 - Nanomicrostructure; 22 - Nanomicrostructure; 23 - Nanomicrostructure; 24 - Nanomicrostructure; 25 - Nanomicrostructure; 26 - Nanomicrostructure; 27 - Nanomicrostructure; 28 - Nanomicrostructure; 29 - Nanomicrostructure; 210 - Nanomicrostructure; 211 - Nanomicrostructure; 212 - Nanomicrostructure; 213 - Nanomicrostructure; 214 - Nanomicrostructure; 215 - Nanomicrostructure; 216 - Nanomicrostructure. Detailed implementation manners

[0117] Next, the technical solutions in the embodiments of the present application will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art based on the present application belong to the scope of protection of the present application.

[0118] When using a traditional optical lens to achieve the functions of focusing or imaging, in order to achieve better imaging quality, smaller aberration and chromatic aberration, a traditional optical imaging system often consists of a combination of multiple traditional optical lenses, resulting in a complex structure, large volume and large weight of the traditional optical imaging system. Moreover, traditional optical lenses are made through processes such as turning, grinding and polishing, and the manufacturing process is complex. In addition, most traditional optical lenses are made of germanium materials, and the cost is relatively high.

[0119] In order to reduce costs, a metasurface lens can be used to achieve the functions of focusing or imaging. The metasurface lens can be mass-produced through a processing and manufacturing process, with a relatively low cost, and is applicable to fields such as security monitoring, mobile phone cameras, and optical communication. However, an imaging system composed of only a single metasurface lens often has serious chromatic aberration and cannot achieve the same imaging quality as a traditional lens group.

[0120] In related technologies, in order to improve the imaging quality of a metasurface lens, the incident light can be achromatized during imaging of the metasurface lens by changing the radius of the metasurface lens, changing the numerical aperture of the metasurface lens, etc. However, since the radius of the metasurface lens is negatively correlated with the bandwidth of the achromatic band, and the numerical aperture of the metasurface lens is also negatively correlated with the bandwidth of the achromatic band, it is impossible to obtain a metasurface lens that simultaneously has a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band.

[0121] To solve the above problems, refer to Figure 1 , Figure 1The first structural diagram of the metasurface lens provided by the embodiments of the present application includes: a substrate 1 and a plurality of nano-microstructures 2. One side of the substrate 1 is formed into a stepped disc structure that gradually increases from the periphery to the center. The stepped disc structure includes at least one step. Each step and the plurality of nano-microstructures 2 on its surface jointly perform dispersion; the plurality of nano-microstructures 2 perform focusing.

[0122] See Figure 2 , Figure 2 is Figure 1 a working principle diagram of the metasurface lens shown in the figure. As Figure 2 shown, R represents the radius of the metasurface lens, θ represents the aperture angle of the metasurface lens, F represents the focal point of the metasurface lens, and f represents the focal length of the metasurface lens. The functional relationship between the numerical aperture of the metasurface lens, the material of the metasurface lens, and the aperture angle of the metasurface lens can be expressed by the following formula (1):

[0123]

[0124] where NA represents the numerical aperture of the metasurface lens, n represents the refractive index of the material of the metasurface lens, and θ represents the aperture angle of the metasurface lens.

[0125] As Figure 2 shown, the incident light irradiates the metasurface lens and forms an image at the focal point F of the metasurface lens after being refracted by the metasurface lens.

[0126] In the embodiments of the present application, the number of steps included in the substrate 1 can be set according to actual needs, and the specific number of steps is not limited. The number of nano-microstructures 2 on each step can also be set according to actual needs, and the specific number of nano-microstructures 2 is not limited.

[0127] Figure 1 In Figure 1 an example is given with the substrate 1 including 2 steps. The 2 steps are specifically step 11 and step 12. Taking Figure 1 as an example, 5 nano-microstructures 2 are arranged on the right side of step 11. The 5 nano-microstructures 2 are respectively: nano-microstructure 21, nano-microstructure 22, nano-microstructure 23, nano-microstructure 24, and nano-microstructure 25. In Figure 1 on the right side of step 11, step 11 and the 5 nano-microstructures 2 jointly perform dispersion on the incident light, and the 5 nano-microstructures 2 on step 11 perform focusing on the incident light. Figure 1 On step 12, 11 nano-microstructures 2 are also arranged. The 11 nano-microstructures 2 are respectively: nano-microstructure 26, nano-microstructure 27, nano-microstructure 28, nano-microstructure 29, nano-microstructure 210, nano-microstructure 211, nano-microstructure 212, nano-microstructure 213, nano-microstructure 214, nano-microstructure 215, and nano-microstructure 216. InFigure 1 The step 12 and the 11 nanostructures 2 therein disperse the incident light together, and the 11 nanostructures 2 on the step 12 focus the incident light.

[0128] In some embodiments, the step of the metasurface lens and the multiple nanostructures 2 on its surface disperse the incident light together, that is, the dispersion of the incident light by the metasurface lens is: the sum of the dispersion of the incident light by the substrate 1 and the dispersion of the incident light by the nanostructures 2. Since the substrate 1 of the metasurface lens is a stepped disc structure that increases sequentially from the periphery to the center, that is, the substrate 1 includes multiple steps, the dispersion of the incident light by the substrate 1 is increased, and thus the dispersion of the incident light by the metasurface lens is increased.

[0129] The functional relationship between the radius of the metasurface lens, the numerical aperture of the metasurface lens, the dispersion of the incident light by the metasurface lens, and the bandwidth of the achromatic band of the metasurface lens can be expressed by the following formula (2):

[0130]

[0131] Wherein, R max represents the radius of the metasurface lens, c represents the speed of light, represents the dispersion of the incident light by the metasurface lens, NA represents the numerical aperture of the metasurface lens, and Δω represents the bandwidth of the achromatic band.

[0132] Based on the above formula (2), it can be seen that the dispersion of the incident light by the metasurface lens is positively correlated with the radius of the metasurface lens, the dispersion of the incident light by the metasurface lens is positively correlated with the numerical aperture of the metasurface lens, and the dispersion of the incident light by the metasurface lens is positively correlated with the bandwidth of the achromatic band of the metasurface lens. Then, when the dispersion of the incident light by the metasurface lens is increased, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens can also be increased, that is, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0133] Moreover, since one side of the substrate 1 of the metasurface lens is formed into a stepped disc structure that increases sequentially from the periphery to the center, and this stepped disc structure is axisymmetric about the principal optical axis, the structure of the substrate 1 of the metasurface lens is simple. Therefore, the substrate 1 can be fabricated by relatively simple processing methods such as ultraviolet lithography, reducing the manufacturing cost and processing difficulty of the metasurface lens.

[0134] Exemplarily, when fabricating the substrate 1 with a stepped disc structure of the metasurface lens, a layer of substrate material can be deposited first, and then ultraviolet lithography is performed on the substrate material according to the determined number of steps of the substrate 1, the width of each step, and the height of the substrate at each step to form the substrate 1 with a stepped disc structure.

[0135] In related technologies, the dispersion of incident light by the meta-lens can be increased by increasing the height of the nano-microstructure 2. However, when the line width of the nano-microstructure 2 is the same, the higher the height of the nano-microstructure 2 and the larger the aspect ratio of the nano-microstructure 2, the greater the processing difficulty and the higher the cost in practical applications. Figure 1 Based on Figure 3 , Figure 3 for Figure 1 The aspect ratio of the nanostructure 2 is the ratio of the height of the nanostructure 2 to the width of the nanostructure 2, that is, Figure 3 The line width is the distance between the centers of two adjacent nanostructures 2, that is, Figure 3 C in.

[0136] In the present application, incident light is dispersed by a substrate 1 having a stepped disk structure and a plurality of nanostructures 2 on its surface. That is, by increasing the dispersion of incident light by the substrate 1 of the metalens, the dispersion of incident light by the metalens can be increased without increasing the height of the nanostructure 2. This reduces the processing difficulty and the cost in practical applications.

[0137] When the substrate 1 of the metalens having the stepped disk structure includes a plurality of steps, the substrate 1 of the metalens may have a multi-height disk structure formed by the plurality of steps.

[0138] In some embodiments, the substrate 1 of the metalens may include three steps, see Figure 4 , Figure 4 This is a second structural diagram of the meta-lens provided in the embodiment of the present application. Figure 4 As shown, the substrate 1 of the metalens includes three steps, specifically step 11, step 12, and step 13. Each step includes a plurality of nano-microstructures 2.

[0139] In some embodiments, the substrate 1 of the metalens may include 4 steps, see Figure 5 , Figure 5 This is the third structural diagram of the meta-lens provided in the embodiment of this application. Figure 5 As shown, the substrate 1 of the metalens includes four steps, specifically step 11, step 12, step 13, and step 14. Each step includes a plurality of nanostructures 2.

[0140] In some embodiments, there are multiple nanostructures 2 on each step of the meta-lens. Figure 6 , Figure 6 This is a top view of the fourth meta-lens provided in the embodiment of the present application. Figure 6As shown, the substrate 1 of the metasurface lens includes a step 11 and a step 12, and there are multiple nano-microstructures 2 on each step.

[0141] The arrangement of the multiple nano-microstructures 2 can be a periodic arrangement, such as Figure 6 As shown, there are multiple preset positions on the step 11, and there is a nano-microstructure 2 at each preset position. The preset positions on each step of the metasurface lens can be set according to requirements. Alternatively, the arrangement of the multiple nano-microstructures 2 can also be a quasi-periodic arrangement, that is, the distances between the multiple nano-microstructures 2 may be different.

[0142] In some embodiments, the working wavelength band of the metasurface lens is the visible light band; the material of the substrate 1 is a material that is transparent to visible light, and the material of the nano-microstructure 2 is a material that is transparent to visible light.

[0143] The wavelength range of the visible light band is 380nm (Nanometer) - 780nm. Since the metasurface lens needs to transmit incident light whose wavelength belongs to the visible light band, the material of the substrate 1 and the material of the nano-microstructure 2 of the metasurface lens are both materials that are transparent to visible light, and the incident light whose wavelength belongs to the visible light band can be transmitted.

[0144] In some embodiments, when the working wavelength band of the metasurface lens is the visible light band, the material of the substrate 1 may include at least one of the following materials: silica, quartz glass, fused quartz, flint glass, optical glass. The material of a nano-microstructure 2 includes at least one of the following materials: silicon nitride, silica, tantalum pentoxide.

[0145] In one implementation, the substrate 1 is a single-layer structure, and the material of the substrate 1 is any one of the above-mentioned multiple materials.

[0146] In another implementation, the substrate 1 is a multi-layer structure, and the material of each layer of the substrate 1 can be different materials, that is, the material of the substrate 1 is a combination of the above-mentioned multiple materials.

[0147] Exemplarily, when fabricating the substrate 1 with a multi-layer structure, such as when the substrate 1 is a three-layer structure, first deposit a layer of silica, then deposit a layer of quartz glass, and finally deposit a layer of flint glass. Then etch the substrate material according to the determined structure of the substrate 1 to obtain the substrate 1 with a multi-layer structure, and the material of the multi-layer structure substrate 1 includes silica, quartz glass and flint glass.

[0148] In one implementation, the nano-microstructure 2 is a single-layer structure, and the material of the nano-microstructure 2 is any one of the above-mentioned multiple materials.

[0149] In another implementation manner, if the nano microstructure 2 is a multi-layer structure, the materials of each layer of the nano microstructure 2 can be different materials, that is, the material of the nano microstructure 2 is a combination of the above-mentioned multiple materials.

[0150] Exemplarily, when fabricating the nano microstructure 2 with a multi-layer structure, such as when the nano microstructure 2 is a three-layer structure, first deposit a layer of silicon nitride, then deposit a layer of silicon dioxide, and finally deposit a layer of tantalum pentoxide. Then, etch the nano microstructure material according to the determined structure of the nano microstructure 2 to obtain the nano microstructure 2 with a multi-layer structure. The material of the nano microstructure 2 with a multi-layer structure thus includes silicon nitride, silicon dioxide, and tantalum pentoxide.

[0151] Moreover, when fabricating the metasurface lens, an adhesive is laid on the fabricated substrate 1, and then the material of the nano microstructure 2 is laid to connect the substrate 1 and the nano microstructure 2. Furthermore, the laid material of the nano microstructure 2 is etched to obtain individual nano microstructures 2. Therefore, the materials of the same layer of the multiple nano microstructures 2 on the metasurface lens are the same. For example, if a nano microstructure 2 is a three-layer structure, and the materials of the three layers are silicon nitride, silicon dioxide, and tantalum pentoxide respectively, then the other nano microstructures 2 on the metasurface lens are also three-layer structures, and the materials of the three layers are also silicon nitride, silicon dioxide, and tantalum pentoxide respectively.

[0152] In some embodiments, when the working wavelength band of the metasurface lens is the visible light band, a visible light antireflection film is provided on the side of the substrate 1 away from the nano microstructure 2; and / or; a visible light antireflection film is provided on the side of the multiple nano microstructures 2 away from the substrate 1.

[0153] When a visible light antireflection film is provided on the metasurface lens, the visible light antireflection film can reduce the reflection of incident light in the visible light band, improve the incidence rate of incident light in the visible light band incident on the metasurface lens, and thereby improve the imaging quality of the metasurface lens.

[0154] Referring to Fig. 7(a), Fig. 7(a) is the fifth structural diagram of the metasurface lens provided by the embodiment of the present application. In Fig. 7(a), the thick lines represent the antireflection film. When the metasurface lens operates in the visible light band, the antireflection film is the visible light antireflection film. The visible light antireflection film can be provided on the first surface and / or the second surface in the manner shown in Fig. 7(a).

[0155] Referring to Fig. 7(b), Fig. 7(b) is the sixth structural diagram of the metasurface lens provided by the embodiment of the present application. In Fig. 7(b), the thick lines represent the antireflection film. When the metasurface lens operates in the visible light band, the antireflection film is the visible light antireflection film. The visible light antireflection film can be provided on the first surface and / or the second surface in the manner shown in Fig. 7(b).

[0156] In some embodiments, the working wavelength band of the metasurface lens is the infrared band; the material of the substrate 1 is an infrared-transparent material, and the material of the nano microstructure 2 is an infrared-transparent material.

[0157] The wavelength range of the infrared band is 0.7um (Micron) - 1000um; since the metasurface lens needs to transmit incident light with wavelengths belonging to the infrared band, the materials of the substrate 1 and the nano microstructure 2 of the metasurface lens are both infrared-transparent materials, which can achieve the transmission of incident light with wavelengths belonging to the infrared band.

[0158] In some embodiments, when the working wavelength band of the metasurface lens is the infrared band, the material of the substrate 1 may include at least one of the following materials: silicon-based glass materials, germanium-based glass materials, and chalcogenide glass materials. The material of a nano microstructure 2 includes at least one of the following materials: silicon-based glass materials, germanium-based glass materials, and chalcogenide glass materials.

[0159] In one implementation, the substrate 1 is a single-layer structure, and the material of the substrate 1 is any one of the above-mentioned various materials.

[0160] In another implementation, the substrate 1 is a multi-layer structure, and the material of each layer of the substrate 1 can be different materials, that is, the material of the substrate 1 is a combination of the above-mentioned various materials.

[0161] Exemplarily, when fabricating the multi-layer structure substrate 1, such as when the substrate 1 is a three-layer structure, first deposit a layer of silicon-based glass material, then deposit a layer of germanium-based glass material, and finally deposit a layer of chalcogenide glass material. Then etch the substrate material according to the determined structure of the substrate 1 to obtain the multi-layer structure substrate 1, and the material of the multi-layer structure substrate 1 also includes silicon-based glass materials, germanium-based glass materials, and chalcogenide glass materials.

[0162] In one implementation, the nano microstructure 2 is a single-layer structure, and the material of the nano microstructure 2 is any one of the above-mentioned various materials.

[0163] In another implementation, the nano microstructure 2 is a multi-layer structure, and the material of each layer of the nano microstructure 2 can be different materials, that is, the material of the nano microstructure 2 is a combination of the above-mentioned various materials.

[0164] Exemplarily, when fabricating the multi-layer structure nano microstructure 2, such as when the nano microstructure 2 is a three-layer structure, first deposit a layer of silicon-based glass material, then deposit a layer of germanium-based glass material, and finally deposit a layer of chalcogenide glass material. Then etch the nano microstructure material according to the determined structure of the nano microstructure 2 to obtain the multi-layer structure nano microstructure 2, and the material of the multi-layer structure nano microstructure 2 also includes silicon-based glass materials, germanium-based glass materials, and chalcogenide glass materials.

[0165] In some embodiments, when the working band of the metasurface lens is the infrared band, an infrared antireflection film is provided on the side of the substrate 1 away from the nano-microstructures 2; and / or; an infrared antireflection film is provided on the side of the plurality of nano-microstructures 2 away from the substrate 1.

[0166] When an infrared antireflection film is provided on the metasurface lens, the infrared antireflection film can reduce the reflection of incident light in the infrared band, improve the incidence rate of incident light in the infrared band incident on the metasurface lens, and thus improve the imaging quality of the metasurface lens.

[0167] Referring to FIG. 7(a), in FIG. 7(a), the thickened line represents the antireflection film. When the metasurface lens operates in the infrared band, the antireflection film is the infrared antireflection film. The infrared antireflection film can be provided on the first surface and / or the second surface in the manner shown in FIG. 7(a).

[0168] Referring to FIG. 7(b), in FIG. 7(b), the thickened line represents the antireflection film. When the metasurface lens operates in the infrared band, the antireflection film is the infrared antireflection film. The infrared antireflection film can be provided on the first surface and / or the second surface in the manner shown in FIG. 7(b).

[0169] In some embodiments, the shape of a nano-microstructure 2 is any one of the following shapes: cylinder, square column, cross, ring, square ring, cylinder inverse structure, square column inverse structure, cross inverse structure.

[0170] The shape of the nano-microstructure 2 can be set according to requirements. Exemplarily, FIG. 8(a) is a structural diagram of a cross-shaped nano-microstructure provided by an embodiment of the present application; FIG. 8(b) is a structural diagram of a ring-shaped nano-microstructure provided by an embodiment of the present application; FIG. 8(c) is a structural diagram of a square-ring-shaped nano-microstructure provided by an embodiment of the present application.

[0171] The cylinder inverse structure means that the hollowed-out part in the middle is in the shape of a cylinder, and the other parts outside the cylinder can be of any shape, such as the shape of a regular hexagonal column shown in FIG. 8(d), or can also be in the shape of a cylinder.

[0172] The square column inverse structure means that the hollowed-out part in the middle is in the shape of a square column, and the other parts outside the square column can be of any shape, such as the shape of a regular hexagonal column shown in FIG. 8(e), or can also be in the shape of a cylinder.

[0173] In some embodiments, in order to obtain a metasurface lens that can reduce chromatic aberration generated when imaging incident light within a working wavelength band (i.e., a preset working wavelength band), the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano-microstructures at each preset position can be determined according to the preset radius and preset working wavelength band of the metasurface lens, that is, the parameters of the metasurface lens are determined. Furthermore, a metasurface lens that can reduce chromatic aberration generated when imaging incident light within the preset working wavelength band can be fabricated according to the determined parameters of the metasurface lens. A metasurface lens that can reduce chromatic aberration generated when imaging incident light within the preset working wavelength band can also be referred to as an achromatic metasurface lens.

[0174] See Figure 9 , Figure 9 FIG. is a first flowchart of a method for determining parameters of a metasurface lens provided by an embodiment of the present application. The method may include the following steps:

[0175] S901: For each preset position of the metasurface lens for which parameters are to be determined, based on the preset radius and preset working wavelength band of the metasurface lens, determine the required phase difference of incident light at two target wavelengths within the preset working wavelength band at this preset position, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference.

[0176] S902: For each nano-microstructure, obtain the modulation phase difference of this nano-microstructure for incident light at the two target wavelengths from the microstructure database, and obtain the maximum value among the modulation phase differences corresponding to each nano-microstructure as the maximum modulation phase difference.

[0177] S903: Based on the maximum required phase difference and the maximum modulation phase difference, determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step.

[0178] S904: For each step of the substrate, calculate the difference between the maximum value among the required phase differences corresponding to each preset position in this step and the maximum modulation phase difference to obtain the substrate phase of this step.

[0179] S905: For each preset position of the metasurface lens, calculate the microstructure phase of the nano-microstructure at this preset position based on the required phase of the incident light at the two target wavelengths at this preset position and the substrate phase of the step to which this preset position belongs.

[0180] S906: Determine the structural parameters of the nano-microstructure that satisfies the microstructure phase corresponding to this preset position in the microstructure database to obtain the structural parameters of the nano-microstructure at this preset position of the metasurface lens.

[0181] Based on the method for determining the parameters of the metasurface lens provided by the embodiments of the present application, the parameters of the metasurface lens can be determined, that is, the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano-microstructures at each preset position are determined. For the metasurface lens fabricated according to the determined parameters, the steps of the metasurface lens and the multiple nano-microstructures on its surface jointly perform dispersion on the incident light. That is, the dispersion of the incident light by the metasurface lens is: the sum of the dispersion of the incident light by the substrate and the dispersion of the incident light by the nano-microstructures. Since the substrate of the metasurface lens is a stepped disc structure that gradually increases from the periphery to the center, that is, the substrate includes multiple steps, the dispersion of the incident light by the substrate is increased, and thus the dispersion of the incident light by the metasurface lens is increased. The dispersion of the incident light by the metasurface lens is positively correlated with the radius of the metasurface lens, the dispersion of the incident light by the metasurface lens is positively correlated with the numerical aperture of the metasurface lens, and the dispersion of the incident light by the metasurface lens is positively correlated with the bandwidth of the achromatic band of the metasurface lens. Then, when the dispersion of the incident light by the metasurface lens is increased, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens can also be increased, that is, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0182] Regarding step S901, there can be multiple preset positions on the steps of the metasurface lens for which the parameters are to be determined, and each preset position is used to set a nano-microstructure.

[0183] The preset working band can belong to the visible light band, and the wavelength range of the visible light band is 380nm - 780nm; or, the preset working band can belong to the infrared band, for example, the preset working band can be 8um - 14um. Since the metasurface lens can reduce the chromatic aberration generated when imaging the incident light within the preset working band, the preset working band can also be referred to as the achromatic band.

[0184] The parameters to be determined for the metasurface lens include: the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano-microstructures at each preset position of the metasurface lens.

[0185] The target wavelengths are the upper limit value and the lower limit value within the preset working band. For example, if the preset working band is 8um - 14um, then the target wavelengths within the preset working band are: 8um and 14um.

[0186] When a metasurface lens is imaging, it is necessary to reduce the chromatic aberration generated when imaging incident light within a preset working band, that is, it is necessary to disperse the incident light within the preset working band. Since the dispersion of the incident light by the metasurface lens is positively correlated with the phase of the incident light within the preset working band that the metasurface lens can provide, increasing the phase that the metasurface lens can provide for the incident light within the preset working band can increase the dispersion of the incident light by the metasurface lens. Correspondingly, for each preset position of the metasurface lens, the required phase of each incident light with a wavelength belonging to the preset working band at this preset position can be determined.

[0187] A nano microstructure at a preset position and the substrate connected to the nano microstructure can be referred to as a unit structure. Correspondingly, the required phase of the incident light at this preset position is the required phase of the unit structure, and the required phase of the unit structure is the sum of the microstructure phase of the nano microstructure at this preset position and the substrate phase of this preset position. Subsequently, after determining the required phases of each preset position, the microstructure phases of the nano microstructures at each preset position and the substrate phases of each preset position can be determined based on the required phases of each preset position. Furthermore, based on the microstructure phases of the nano microstructures at each preset position and the substrate phases of each preset position, the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the structural parameters of the nano microstructure at each preset position can be determined.

[0188] In some embodiments, step S901 may include the following steps:

[0189] Step 1: For each preset position of the metasurface lens for which parameters are to be determined, based on the preset radius and preset working band of the metasurface lens, according to the first preset formula, calculate the required phases of the incident light of two target wavelengths within the preset working band at this preset position.

[0190] Among them, the first preset formula is:

[0191]

[0192] Among them, represents the required phase, (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant.

[0193] Step 2: Calculate the difference between the required phases of the incident light of the two target wavelengths at this preset position to obtain the required phase difference of the incident light of the two target wavelengths at this preset position.

[0194] Exemplarily, see Figure 10 ,Figure 10 A curve graph showing the correspondence between each preset position of the metasurface lens provided in the embodiment of the present application and the required phase of the incident light at each preset position. Figure 10 The dashed line in [graph] represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 8 μm at each preset position; the solid line represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 9 μm at each preset position; the curve with flowers represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 10 μm at each preset position; the curve with circles represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 11 μm at each preset position; the curve with a cross pattern represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 12 μm at each preset position; the curve with triangles represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 13 μm at each preset position; the curve with an '×' shape represents the correspondence between each preset position of the metasurface lens and the required phase of the incident light with a wavelength of 14 μm at each preset position.

[0195] Figure 10 In [graph], the horizontal axis represents each preset position of the metasurface lens, and the point with 0 on the horizontal axis represents the center of the metasurface lens. The unit of the horizontal axis is meters, then Figure 10 the radius of the shown metasurface lens is 400 μm, that is, 4×10 -4 meters. Figure 10 The vertical axis in [graph] represents the required phase of the incident light at each preset position.

[0196] Based on Figure 10 it can be obtained that at the same preset position of the metasurface lens, the required phase of the incident light at this preset position is negatively correlated with the wavelength of the incident light, that is, the larger the wavelength of the incident light, the smaller the required phase of the incident light at this preset position; the smaller the wavelength of the incident light, the larger the required phase of the incident light at this preset position. And for each wavelength, the required phase of the incident light of this wavelength at the preset position at the center of the metasurface lens is the largest, and the closer the preset position is to the edge of the metasurface lens, the smaller the required phase of the incident light. At the preset position at the edge of the metasurface lens, the required phase of the incident light is 0.

[0197] For each target wavelength, the electronic device can calculate the required phase of the incident light of this target wavelength at each preset position of the metasurface lens based on the above formula (3). After calculating the required phases of the incident lights of two target wavelengths at each preset position of the metasurface lens, the electronic device can calculate the difference between the required phases of the incident lights of these two target wavelengths at each preset position to obtain the corresponding required phase difference at each preset position.

[0198] Exemplarily, such asFigure 10 As shown, the preset working wavelength band is 8um - 14um, and the target wavelengths within the preset working wavelength band are 8um and 14um. The electronic device calculates the required phase differences of the incident light of these two target wavelengths at each preset position of the metasurface lens, and obtains the required phase difference corresponding to each preset position. For example, for the preset position with the abscissa of 0, calculate the difference in the required phases of the incident light of these two target wavelengths at the preset position with the abscissa of 0, and obtain the required phase difference corresponding to the preset position with the abscissa of 0; for the preset position with the abscissa of 2, calculate the difference in the required phases of the incident light of these two target wavelengths at the preset position with the abscissa of 2, and obtain the required phase difference corresponding to the preset position with the abscissa of 2; for the preset position with the abscissa of -2, calculate the difference in the required phases of the incident light of these two target wavelengths at the preset position with the abscissa of -2, and obtain the required phase difference corresponding to the preset position with the abscissa of -2.

[0199] Based on the above processing, the required phase differences of the incident light of the two target wavelengths at each preset position of the metasurface lens can be determined. Furthermore, based on the required phase differences of the incident light of the two target wavelengths at each preset position of the metasurface lens, the parameters of the metasurface lens are determined, that is, the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano - microstructures at each preset position are determined. Thus, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic wavelength band can be obtained.

[0200] In some embodiments, an even - order aspheric phase can also be used as the required phase of the incident light of the target wavelength at this preset position. The even - order aspheric phase is the phase calculated based on the even - order aspheric polynomial. Subsequently, the electronic device calculates the difference in the required phases of the incident light of these two target wavelengths at this preset position, and obtains the required phase difference of the incident light of these two target wavelengths at this preset position.

[0201] After the electronic device calculates the required phase differences corresponding to each preset position of the metasurface lens, the maximum value (i.e., the maximum required phase difference) among these multiple required phase differences can be determined. The maximum required phase difference indicates that for the incident light with a wavelength belonging to the preset working wavelength band, it is the maximum required phase difference of the phase that needs to be jointly provided by the substrate and the nano - microstructures. Exemplarily, as Figure 10 shown, the maximum required phase difference is the difference between the required phase of the incident light with a wavelength of 8um and the required phase of the incident light with a wavelength of 14um at the preset position with the abscissa of 0.

[0202] For step S902, in some embodiments, the electronic device may pre - construct a microstructure database. For example, the electronic device may pre - design nano - microstructures with different structural parameters, simulate each nano - microstructure respectively, obtain the modulation phase of the nano - microstructure for incident light of each wavelength, and store the structural parameters of the nano - microstructure and the modulation phase of the nano - microstructure for incident light of each wavelength in correspondence to obtain the microstructure database. The structural parameters of the nanostructure include: the width of the nano - microstructure, the height of the nano - microstructure, the shape of the nano - microstructure, the material of the nano - microstructure, and the period of the nano - microstructure.

[0203] The period of the nano - microstructure is the distance between the edges of the same side of two adjacent nano - microstructures, such as Figure 3 D in

[0204] Exemplarily, referring to Table (1), Table (1) is a microstructure database provided by an embodiment of the present application.

[0205] Table (1)

[0206]

[0207] For each nano - microstructure, the structural parameters of the nano - microstructure and the modulation phase for the target wavelength can be directly found from the microstructure database.

[0208] As shown in Table (1), the modulation phase of nano - microstructure 1 for incident light of wavelength 1 is The modulation phase for incident light of wavelength 2 is The modulation phase for incident light of wavelength 3 is The material of nano - microstructure 1 is silicon dioxide, the width is d1, the height is h1, the shape is cylindrical, and the period is 3.5um; the modulation phase of nano - microstructure 2 for incident light of wavelength 1 is The modulation phase for incident light of wavelength 2 is The modulation phase for incident light of wavelength 3 is The material of nano - microstructure 2 is silicon nitride, the width is d2, the height is h2, the shape is a square ring, and the period is 4um.

[0209] All the nano - microstructures included in a metasurface lens have the same material. If it is necessary to fabricate a metasurface lens with a nano - microstructure made of silicon dioxide, then nano - microstructures made of silicon dioxide are found from the microstructure database; if it is necessary to fabricate a metasurface lens with nano - microstructures made of silicon dioxide and silicon nitride, then nano - microstructures made of silicon dioxide and silicon nitride are found from the microstructure database.

[0210] For each nano microstructure, after the electronic device obtains the modulation phase of the incident light of the nano microstructure for the target wavelength, it can calculate the difference between the modulation phases of the incident light of the nano microstructure for two target wavelengths to obtain the modulation phase difference corresponding to the nano microstructure. Furthermore, the electronic device can obtain the modulation phase differences corresponding to each nano microstructure and determine the maximum value among the multiple modulation phase differences (i.e., the maximum modulation phase difference). The maximum modulation phase difference indicates the maximum modulation phase difference that the nano microstructure can provide for the incident light with a wavelength belonging to the preset working band.

[0211] In this embodiment, the execution order of step S901 and step S902 is not limited. Step S901 can be executed first, or step S902 can be executed first. For example, step S901 can be executed first and then step S902; or step S902 can be executed first and then step S901; or step S901 and step S902 can also be executed simultaneously.

[0212] Regarding step S903 and step S904, the required phase of the incident light of the target wavelength at a preset position of the metasurface lens is also: the phase mutation introduced at the preset position when the metasurface lens reduces the chromatic aberration generated by imaging the incident light of the target wavelength.

[0213] For each preset position of the metasurface lens, the required phase corresponding to the preset position is jointly provided by the substrate and the nano microstructure at the preset position, that is, the required phase corresponding to the preset position is the sum of the substrate phase of the step to which the preset position belongs and the microstructure phase of the nano microstructure at the preset position. Therefore, the number of steps of the substrate and the width of each step can be determined first according to the maximum required phase difference and the maximum modulation phase difference, that is, multiple steps of the substrate are determined. Then, for each step of the substrate, the difference between the maximum value among the required phase differences corresponding to each preset position in the step and the maximum modulation phase difference is calculated to obtain the substrate phase of the step. The substrate phases of each preset position in the same step are the same. Subsequently, according to the substrate phase of the step, the height of the substrate at each step is determined.

[0214] In some embodiments, the electronic device can calculate the number of steps of the substrate, the width of each step, and the height of the substrate at each step according to the maximum required phase difference and the maximum modulation phase difference.

[0215] See Figure 11 , on the basis of Figure 9 , step S903 may include the following steps:

[0216] S9031: Calculate the quotient of the maximum required phase difference and the maximum modulation phase difference, and round up the calculation result to obtain the number of steps of the substrate.

[0217] S9032: For each step of the substrate, calculate the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step.

[0218] Among them, the coefficient corresponding to a step represents the position of the step in the substrate.

[0219] S9033: Determine the height of the substrate at the step based on the substrate phase at the step and the refractive index of the material of the substrate.

[0220] Exemplarily, the functional relationship between the maximum required phase difference, the maximum modulation phase difference, and the number of steps of the substrate can be expressed by the following formula (4):

[0221]

[0222] Among them, N represents the number of steps of the substrate; round means taking the integer of the calculation result in the direction of increasing the absolute value; represents the maximum required phase difference; represents the maximum modulation phase difference.

[0223] Since the maximum required phase difference can represent the maximum required phase difference of the phase jointly provided by the substrate and the nanostructure for incident light whose wavelength belongs to the preset working wavelength band, and the maximum modulation phase difference can represent the maximum modulation phase difference that the nanostructure can provide for incident light whose wavelength belongs to the preset working wavelength band, therefore, the quotient of the maximum required phase difference and the maximum modulation phase difference can also represent the number of steps required for the substrate to provide sufficient substrate phase. The number of steps is a positive integer, and rounding up the quotient of the maximum required phase difference and the maximum modulation phase difference gives the number of steps of the substrate.

[0224] In some embodiments, step S9032 may include the following steps:

[0225] Step 1: Calculate the product of the maximum modulation phase difference and the coefficient corresponding to the step as the first phase parameter of the step.

[0226] Step 2: Calculate the difference between the maximum required phase difference and the first phase parameter of the step to obtain the second phase parameter of the step.

[0227] Step 3: Determine, from the preset positions of the metasurface lens, the preset position corresponding to the required phase difference that is the same as the second phase parameter of the step, to obtain the position of the edge of the step in the metasurface lens.

[0228] Step 4: Determine the diameter of the circle with the distance between the edge of the step and the center of the metasurface lens as the radius and the center of the metasurface lens as the center of the circle, to obtain the diameter of the circular region to which the step belongs.

[0229] Step 5: If the step is the highest step in the substrate, determine the diameter of the circular region to which the step belongs as the width of the step.

[0230] Step 6: If the step is not the highest step in the substrate, calculate the difference between the radius of the circular region to which the step belongs and the radius of the circular region to which the upper adjacent step belongs, and obtain the width of the step.

[0231] For each step, the electronic device can determine the coefficient corresponding to the step. The coefficient corresponding to a step represents the position of the step in the substrate. In the order from the highest to the lowest height of the steps, the higher the height of the step, that is, the closer the position of the step is to the center of the substrate, the smaller the coefficient corresponding to the step; the lower the height of the step, that is, the closer the position of the step is to the edge of the substrate, the larger the coefficient corresponding to the step. Exemplarily, the coefficient corresponding to a step is the serial number of the position of the step in the substrate. As Figure 4 shown, the number of steps of the substrate is 3. Sort the 3 steps in the order from the highest to the lowest height, and obtain that the serial number of step 13 is 1, the serial number of step 12 is 2, and the serial number of step 11 is 3. Correspondingly, the coefficient corresponding to step 11 is 3, the coefficient corresponding to step 12 is 2, and the coefficient corresponding to step 13 is 1.

[0232] Subsequently, for each step, the electronic device calculates the product of the maximum modulation phase difference and the coefficient corresponding to the step to obtain the first phase parameter of the step. Furthermore, the electronic device calculates the difference between the maximum required phase difference and the first phase parameter of the step to obtain the second phase parameter of the step. The second phase parameter of the step is the phase that the step needs to provide.

[0233] Furthermore, the electronic device determines, from the required phase differences, the required phase difference that is the same as the second phase parameter of the step (which can be called the target required phase difference), and determines the preset position corresponding to the target required phase difference in the metasurface lens. The determined preset position is the position of the edge of the step in the metasurface lens.

[0234] Furthermore, the electronic device determines the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and with the center of the metasurface lens as the center of the circle, and obtains the diameter of the circular region to which the step belongs.

[0235] If the step is the highest step in the substrate, the diameter of the circular region to which the step belongs is the width of the step.

[0236] If the step is not the highest step in the substrate, the electronic device can determine the width of the step according to the radius of the circular region to which the step belongs and the radius of the circular region to which the upper adjacent step of the step belongs. The upper adjacent step of a step is adjacent to the step, and the height of the upper adjacent step is greater than the height of the step. Exemplarily, as Figure 4 shown, the upper adjacent step of step 11 is step 12, and the upper adjacent step of step 12 is step 13.

[0237] For example, when the substrate includes two steps, as Figure 1 shown, the electronic device calculates the difference between the diameter of the metasurface lens and the width of step 12, and can directly obtain the width of step 11. Exemplarily, the maximum modulation phase difference is 20, the coefficient corresponding to step 12 is 1, and the maximum required phase difference is 35. Then the first phase parameter of step 12 is 20, and the second phase parameter of step 12 is 15. Figure 10 In, the diameter of the metasurface lens is 800 um. At a preset position in the metasurface lens that is close to 300 um from the center of the metasurface lens, the required phase difference at this preset position is also 15. Therefore, the edge of step 12 is located at a position in the metasurface lens that is close to 300 um from the center of the metasurface lens. Then the width of step 12 is close to 600 um. Correspondingly, the width of step 11 is close to 100 um.

[0238] When the number of steps included in the substrate is greater than 2, for example, when the substrate includes three steps, as Figure 4 shown, the maximum modulation phase difference is 20, the coefficient corresponding to step 13 is 1, and the maximum required phase difference is 45. Then the first phase parameter of step 13 is 20, and the second phase parameter of step 13 is 25. The diameter of the metasurface lens is 800 um. If at a preset position in the metasurface lens that is 200 um from the center of the metasurface lens, the required phase difference at this preset position is also 25. Therefore, the edge of step 13 is located at a preset position in the metasurface lens that is 200 um from the center of the metasurface lens, that is, the width of step 13 is 400 um. The coefficient corresponding to step 12 is 2, then the first phase parameter of step 12 is 40, and the second phase parameter of step 12 is 5. If at a preset position in the metasurface lens that is 300 um from the center of the metasurface lens, the required phase difference at this preset position is 5. Therefore, the edge of step 12 is located at a preset position in the metasurface lens that is 300 um from the center of the metasurface lens, that is, the width of step 12 is 100 um. Further. The width of step 11 is 100 um.

[0239] In some embodiments, since the preset positions in the metasurface lens are preset in advance and each preset position is used to set the nano-microstructures. When determining the position of the edge of the step, the position of the edge of the step may be a preset position for setting the nano-microstructures, that is, the position of the edge of the step conflicts with the preset position for setting the nano-microstructures. At this time, the position of the edge of the step can be moved according to the determined width of the step to avoid the conflict between the position of the edge of the step and the preset position for setting the nano-microstructures.

[0240] For each step of the substrate, the step includes a plurality of preset positions. Each preset position corresponds to a required phase difference, and the plurality of preset positions in the step correspond to a plurality of required phase differences. The electronic device can obtain the maximum value among the plurality of required phase differences corresponding to the respective preset positions in the step (which can be referred to as the required phase difference corresponding to the step).

[0241] For each preset position of the metasurface lens, since the required phase corresponding to this preset position is jointly provided by the substrate and the nano-microstructures at this preset position, that is, the required phase corresponding to this preset position is the sum of the substrate phase of the step to which this preset position belongs and the microstructure phase of the nano-microstructures at this preset position. And the phase that the nano-microstructures at this preset position can provide is limited, then the phase that the nano-microstructures cannot provide can only be provided by the substrate at this preset position. The required phase difference corresponding to this step is: for incident light with a wavelength belonging to the preset working band, the maximum required phase difference of the phase jointly provided by the substrate and the nano-microstructures of this step; the maximum modulation phase difference is: the maximum modulation phase difference that the nano-microstructures can provide for incident light with a wavelength belonging to the preset working band. Therefore, calculating the difference between the required phase difference corresponding to this step and the maximum modulation phase difference is exactly the phase that needs to be provided by this step (i.e., the substrate phase of this step).

[0242] Exemplarily, refer to Figure 12 , Figure 12 is a curve graph showing the correspondence between the preset positions of the metasurface lens provided by the embodiments of the present application and the substrate phases of the incident light at the respective preset positions. As Figure 12 shown, Figure 12The dashed lines therein represent the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 8 μm at each preset position; the solid lines represent the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 9 μm at each preset position; the curve with flowers represents the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 10 μm at each preset position; the curve with circles represents the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 11 μm at each preset position; the curve with a cross of rice characters represents the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 12 μm at each preset position; the curve with triangles represents the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 13 μm at each preset position; the curve with ×-shapes represents the corresponding relationships between the preset positions of the metasurface lens and the substrate phases of the incident light with a wavelength of 14 μm at each preset position.

[0243] Figure 12 In the [figure], the horizontal axis represents the preset positions of the metasurface lens, and the point with 0 in the horizontal axis represents the center of the metasurface lens. The unit of the horizontal axis is meter, then Figure 12 the radius of the shown metasurface lens is 400 μm, that is, 4×10 -4 meters. Figure 12 The vertical axis in the [figure] represents the substrate phases of the incident light at each preset position.

[0244] Based on Figure 12 it can be obtained that for each incident light, the substrate phases of the incident light at each preset position on the same step of the substrate of the metasurface lens (i.e., the substrate phase of this step) are the same. The substrate of the metasurface lens includes 2 steps. The higher the height of the step, the larger the substrate phase of this step. And in the same step of the metasurface lens, the substrate phase of this step is negatively correlated with the wavelength of the incident light, that is, the larger the wavelength of the incident light, the smaller the substrate phase of this step; the smaller the wavelength of the incident light, the larger the substrate phase of this step.

[0245] Furthermore, after determining the number of steps of the substrate and the width of each step, the respective steps included in the substrate can be determined. For each step of the substrate, the electronic device can calculate the substrate phase of this step based on the maximum value of the required phase differences corresponding to the preset positions in this step and the maximum modulation phase difference, and determine the height of the substrate at this step based on the substrate phase of this step and the refractive index of the material of the substrate.

[0246] In some embodiments, step S9033 may include the following steps:

[0247] Step 1: Based on the second preset formula, determine the height of the substrate at this step according to the substrate phase of this step and the refractive index of the material of the substrate.

[0248] Among them, the second preset formula is:

[0249]

[0250] Among them, represents the substrate phase of this step, n represents the refractive index of the substrate material, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at this step.

[0251] After the material of the substrate is determined, the refractive index of the substrate material is also determined. Furthermore, it is possible to determine the height of each step according to the substrate phase of each step, the refractive index of the substrate material, and the two target wavelengths. For example, as Figure 3 shown, the height of step 11 is h1, and the height of step 12 is h2.

[0252] Based on the above processing, determine the number of steps of the substrate and the width of each step based on the maximum required phase difference and the maximum modulation phase difference; for each step of the substrate, based on the required phase difference and the maximum modulation phase difference corresponding to this step, obtain the substrate phase of this step, and then determine the height of the substrate at this step according to the substrate phase of this step, that is, determine the parameters of the substrate of the metasurface lens. Furthermore, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0253] For steps S905 and S906, the heights of the nano-microstructures at each preset position of the metasurface lens are the same. For each preset position of the metasurface lens, since the required phase corresponding to this preset position is jointly provided by the substrate and the nano-microstructure at this preset position, and the phase that the nano-microstructure can provide is limited, the phase that the nano-microstructure cannot provide can only be provided by the substrate at this preset position. After the electronic device determines the substrate phase of the step to which this preset position belongs, it can calculate the phase that the nano-microstructure at this preset position of the metasurface lens can provide for the incident light (i.e., the microstructure phase of the nano-microstructure at this preset position) according to the required phase of the incident light at this preset position and the substrate phase of the step to which this preset position belongs for the two target wavelengths.

[0254] Exemplarily, refer to Figure 13 , Figure 13 is a curve graph showing the correspondence between each preset position of the metasurface lens provided in the embodiment of the present application and the microstructure phase of the nano-microstructure at each preset position. As Figure 13 shown, Figure 13The dashed lines in it represent the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 8 μm; the solid lines represent the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 9 μm; the curve with flowers represents the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 10 μm; the curve with circles represents the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 11 μm; the curve with a cross represents the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 12 μm; the curve with triangles represents the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 13 μm; the curve with an × represents the correspondence between each preset position of the metasurface lens and the microstructure phase of the nanostructures at each preset position for incident light with a wavelength of 14 μm.

[0255] Figure 13 In it, the horizontal axis represents each preset position of the metasurface lens, and the point with 0 in the horizontal axis represents the center of the metasurface lens. The unit of the horizontal axis is μm, then Figure 13 the radius of the shown metasurface lens is 400 μm. Figure 13 In it, the vertical axis represents the microstructure phase of the nanostructures at each preset position of the incident light.

[0256] Based on Figure 13 it can be obtained that for each preset position of the metasurface lens, the microstructure phase of the nanostructures at this preset position is: the difference between the required phase of the incident light with a wavelength belonging to the preset working band at this preset position and the substrate phase of the step to which this preset position belongs. The substrate of the metasurface lens includes 2 steps. In the same preset position of the metasurface lens, the microstructure phase of the nanostructures at this preset position is negatively correlated with the wavelength of the incident light, that is, the larger the wavelength of the incident light, the smaller the microstructure phase of the nanostructures at this preset position; the smaller the wavelength of the incident light, the larger the microstructure phase of the nanostructures at this preset position.

[0257] In one implementation, the electronic device can select a target wavelength from two target wavelengths within the preset working band, and for each preset position of the metasurface lens, calculate the difference between the required phase of the incident light with this target wavelength at this preset position and the substrate phase of the step to which this preset position belongs, to obtain the microstructure phase of the nanostructures at this preset position corresponding to this target wavelength.

[0258] Exemplarily, according to the following formula (6), the microstructure phase of the nanostructure at a preset position of the metasurface lens for the incident light of the target wavelength can be calculated:

[0259]

[0260] where (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, represents the microstructure phase of the nanostructure at the preset position with coordinates (x, y) for the incident light of the target wavelength, represents the required phase of the incident light of the target wavelength at the preset position with coordinates (x, y), represents the substrate phase of the step to which the preset position with coordinates (x, y) belongs.

[0261] In another implementation, the electronic device can select a target wavelength from two target wavelengths within a preset working band. For each preset position of the metasurface lens, calculate the sum of the required phase difference of the incident light of the target wavelength at this preset position and the required phase corresponding to this preset position, and calculate the difference between this sum value and the substrate phase of the step to which this preset position belongs, so as to obtain the microstructure phase of the nanostructure at this preset position corresponding to the target wavelength.

[0262] Then, the electronic device determines, from the microstructure database, the structural parameters of the nanostructure whose modulation phase for the incident light of the target wavelength is the same as this microstructure phase and whose modulation phase difference for the incident lights of the two target wavelengths is the same as the required phase difference corresponding to this preset position, so as to obtain the structural parameters of the nanostructure at this preset position of the metasurface lens.

[0263] If there is no nanostructure in the microstructure database whose modulation phase for the incident light of the target wavelength is the same as this microstructure phase and whose modulation phase difference for the incident lights of the two target wavelengths is the same as the required phase difference corresponding to this preset position, the electronic device can first select, from the microstructure database, the nanostructure whose modulation phase for the incident light of the target wavelength is the same as this microstructure phase as the alternative nanostructure. Then, for each alternative nanostructure, the electronic device can calculate the modulation phase difference of this alternative nanostructure for the incident lights of the two target wavelengths as the modulation phase difference corresponding to this alternative nanostructure. Then calculate the absolute value of the difference between the modulation phase difference corresponding to this alternative nanostructure and the required phase difference corresponding to this preset position to obtain the phase offset corresponding to this alternative nanostructure.

[0264] Furthermore, the electronic device can determine the minimum phase shift from the phase shifts corresponding to the alternative nanostructures, and determine the structural parameters of the alternative nanostructure corresponding to the minimum phase shift as the structural parameters of the nanostructure of the metasurface lens at the preset position.

[0265] Exemplarily, the required phase difference corresponding to preset position 1 is 20, and the microstructure phase of the nanostructure at preset position 1 corresponding to target wavelength 1 is 35. The microstructure database records that: the modulation phase of nanostructure 1 for the incident light of target wavelength 1 is 35, and the modulation phase for the incident light of target wavelength 2 is 16; the modulation phase of nanostructure 2 for the incident light of target wavelength 1 is 35, and the modulation phase for the incident light of target wavelength 2 is 13; the modulation phase of nanostructure 3 for the incident light of target wavelength 1 is 34, and the modulation phase for the incident light of target wavelength 2 is 14.

[0266] The electronic device first selects, from the microstructure database, the nanostructures whose modulation phases for the incident light of this target wavelength 1 are the same as the microstructure phase, namely nanostructure 1 and nanostructure 2, as alternative nanostructures. Then, the electronic device calculates the difference between the modulation phase of nanostructure 1 for the incident light of target wavelength 1 and the modulation phase for the incident light of target wavelength 2, and obtains that the modulation phase difference corresponding to nanostructure 1 is 19; calculates the difference between the modulation phase of nanostructure 2 for the incident light of target wavelength 1 and the modulation phase for the incident light of target wavelength 2, and obtains that the modulation phase difference corresponding to nanostructure 1 is 22.

[0267] Furthermore, the electronic device calculates the absolute value of the difference between the modulation phase difference corresponding to nanostructure 1 and the required phase difference corresponding to this preset position, and obtains that the phase shift corresponding to nanostructure 1 is 1; calculates the absolute value of the difference between the modulation phase difference corresponding to nanostructure 2 and the required phase difference corresponding to this preset position, and obtains that the phase shift corresponding to nanostructure 2 is 2. The minimum phase shift is 1, and the phase shift corresponding to nanostructure 1 is 1. Therefore, the electronic device can determine the structural parameters of nanostructure 1 as the structural parameters of the nanostructure of the metasurface lens at preset position 1.

[0268] In addition, since the material of the nanostructure and the period of each nanostructure have been preset, when determining the structural parameters of the nanostructure at each preset position in the metasurface lens, the structural parameters of the nanostructure that can provide this microstructure phase and meet the preset material and period of the nanostructure can be searched from the microstructure database. The structural parameters of the nanostructure include: the width of the nanostructure, the height of the nanostructure, and the shape of the nanostructure.

[0269] See Figure 14 ,Figure 14 The third flowchart of the method for determining parameters of the metasurface lens provided by the embodiment of the present application.

[0270] S1401: Design the multi-wavelength required phase.

[0271] The multi-wavelength required phase is the required phase of the incident light of two target wavelengths within the preset working band in each preset position of the metasurface lens in the foregoing embodiment. The multi-wavelength required phase can also be referred to as the total required phase.

[0272] Exemplarily, when it is required to obtain a metasurface lens with a radius of 400 um, a focal length of 800 um, an aperture number (which can also be referred to as the F number) of 1, and a preset working band of 9 um - 14 um, that is, an achromatic bandwidth of 5 um, the multi-wavelength required phase is the required phase of the incident light with a wavelength of 9 um and the incident light with a wavelength of 14 um in each preset position of the metasurface lens. For each preset position of the metasurface lens, the electronic device can use the even aspherical phase as the required phase of the incident light of the target wavelength at this preset position, or calculate the required phase of the incident light of the target wavelength at this preset position according to the first preset formula.

[0273] S1402: Obtain the pre-constructed microstructure database.

[0274] The electronic device can obtain the pre-constructed microstructure database, in which the structural parameters of each nano-microstructure and the modulation phase for the incident light of each wavelength are correspondingly stored. The structural parameters of the nanostructure include: the width of the nano-microstructure, the height of the nano-microstructure, the shape of the nano-microstructure, the material of the nano-microstructure, and the period of the nano-microstructure.

[0275] S1403: Select the gradient substrate height, the number of steps, and the gradient substrate disk radius according to the maximum phase difference of the required phase and the maximum phase difference of the microstructure modulation.

[0276] The maximum phase difference of the required phase is the maximum required phase difference in the foregoing embodiment, that is, the difference between the required phase of the incident light with a wavelength of 9 um and the required phase of the incident light with a wavelength of 14 um at the preset position at the center of the metasurface lens; the maximum phase difference of the microstructure modulation is the maximum modulation phase difference in the foregoing embodiment; the gradient substrate disk radius is the width of each step in the foregoing embodiment. Subsequently, the electronic device calculates the quotient of the maximum required phase difference and the maximum modulation phase difference, and rounds up the calculation result to obtain the number of steps of the substrate, that is, calculates the number of steps of the substrate based on formula (4) in the foregoing embodiment, for example, the number of steps is 2.

[0277] After determining the number of steps of the substrate, the electronic device can determine the coefficient corresponding to each step of the substrate according to the position of each step of the substrate in the substrate. Furthermore, for each step of the substrate, the electronic device calculates the product of the maximum modulation phase difference and the coefficient corresponding to this step as the first phase parameter of this step. Then, it calculates the difference between the maximum required phase difference and the first phase parameter of this step to obtain the second phase parameter of this step. And from the preset positions of the metasurface lens, it determines the preset position corresponding to the required phase difference that is the same as the second phase parameter of this step, and obtains the position of the edge of this step in the metasurface lens. Subsequently, it determines the diameter of a circle with the distance between the edge of this step and the center of the metasurface lens as the radius and the center of the metasurface lens as the center of the circle, and obtains the diameter of the circular region to which this step belongs. Correspondingly, the electronic device can obtain the diameters of the circular regions to which each step of the substrate of the metasurface lens belongs.

[0278] If this step is the highest step in the substrate, determine the diameter of the circular region to which this step belongs as the width of this step. If this step is not the highest step in the substrate, calculate the difference between the radius of the circular region to which this step belongs and the radius of the circular region to which the upper adjacent step belongs to obtain the width of this step.

[0279] For example, as Figure 10 shown, when the number of steps is 2, the required phase difference corresponding to the position 278.25 um away from the center of the metasurface lens is the same as the second phase parameter, then the width of the highest step is 556.5 um, and the width of the lowest step is 121.75 um.

[0280] For each step of the substrate, calculate the difference between the maximum value of the required phase differences corresponding to the preset positions in this step and the maximum modulation phase difference to obtain the substrate phase of this step. Furthermore, based on the second preset formula, according to the substrate phase of this step and the refractive index of the material of the substrate, calculate the height of the substrate at this step. At this time, λ1 is 9 um and λ2 is 14 um. Based on the substrate phase of this step and the refractive index of the material of the substrate, h can be calculated based on the second preset formula, that is, the height of the substrate at this step is determined. For example, the substrate includes 2 steps, and it is calculated that the height of the substrate of the metasurface lens at the highest step is 20 um.

[0281] S1404: Calculate the gradient substrate phase.

[0282] The gradient substrate phase includes the substrate phase of each step. For each step of the metasurface lens, the substrate phase of this step is also the difference between the maximum value (i.e., the required phase difference corresponding to this step) of the multiple required phase differences corresponding to the preset positions in this step in the foregoing embodiment and the maximum modulation phase difference.

[0283] S1405: Calculate the required phase of the microstructure.

[0284] The required phase of the microstructure is the microstructure phase of the nano-microstructures at each preset position of the metasurface lens in the foregoing embodiment, that is, the phase that the nano-microstructures at the preset position can provide for the incident light. After the electronic device calculates the required phase of the incident light with two target wavelengths at the preset position in the step and the substrate phase of the step to which the position belongs, the microstructure phase of the nano-microstructures at the preset position can be calculated.

[0285] S1406: Match to obtain the microstructure arrangement and complete the design of the metasurface lens.

[0286] The microstructure arrangement includes the structural parameters of the nano-microstructures at each preset position in the metasurface lens. The structural parameters of a nano-microstructure include: the width of the nano-microstructure, the height of the nano-microstructure, the shape of the nano-microstructure, the material of the nano-microstructure, and the period of the nano-microstructure. Since the material and period of the nano-microstructure have been preset, for each preset position, after the electronic device obtains the microstructure phase of the nano-microstructure at the preset position, it can search in the microstructure database for the structural parameters of the nano-microstructure that can provide the microstructure phase and satisfy the preset material and period of the nano-microstructure. The structural parameters of the nano-microstructure include: the width of the nano-microstructure, the height of the nano-microstructure, and the shape of the nano-microstructure. For example, if the preset material of the nano-microstructure is silicon dioxide and the period is 3.5 μm, the height of the nano-microstructure determined from the microstructure database is 30 μm, the width is 3 μm, and the shape is cylindrical.

[0287] After determining the structural parameters of the nano-microstructures at each preset position, the arrangement of the nano-microstructures included in the metasurface lens is determined. After determining the parameters of the substrate of the metasurface lens and the structural parameters of the nano-microstructures, the design of the metasurface lens is completed.

[0288] Based on the above processing, the parameters of the metasurface lens can be determined, that is, the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano-microstructures at each preset position are determined. For the metasurface lens fabricated according to the determined parameters, the steps of the metasurface lens and the multiple nano-microstructures on its surface jointly disperse the incident light. That is, the dispersion of the incident light by the metasurface lens is: the sum of the dispersion of the incident light by the substrate and the dispersion of the incident light by the nano-microstructures. Since the substrate of the metasurface lens is a stepped disc structure, that is, the substrate includes multiple steps, the dispersion of the incident light by the substrate is increased, and thus the dispersion of the incident light by the metasurface lens is increased. The dispersion of the incident light by the metasurface lens is positively correlated with the radius of the metasurface lens, the dispersion of the incident light by the metasurface lens is positively correlated with the numerical aperture of the metasurface lens, and the dispersion of the incident light by the metasurface lens is positively correlated with the bandwidth of the achromatic band of the metasurface lens. Then, when the dispersion of the incident light by the metasurface lens is increased, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens can be increased, that is, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0289] Moreover, since the required phase at each preset position of the metasurface lens is jointly provided by the substrate and the nano-microstructures at this preset position, and the phase that the nano-microstructures at this preset position can provide is limited, the phase that the nano-microstructures cannot provide is provided by the substrate at this preset position. That is, the substrate of the metasurface lens shares the phase pressure for the nano-microstructures of the metasurface lens.

[0290] In addition, since one side of the substrate of the metasurface lens is formed into a stepped disc structure that increases successively from the periphery to the center, and this stepped disc structure is axisymmetric about the principal optical axis, the structure of the substrate is simple. Therefore, the fabrication of the substrate can be completed by relatively simple processing methods such as ultraviolet lithography, reducing the fabrication cost and processing difficulty of the metasurface lens. And because the fabrication method of the substrate is relatively simple, it is also convenient for mass production by machines, and the probability of the substrate having defects during mass production is relatively low.

[0291] In some embodiments, after determining the parameters of the substrate of the metasurface lens and the parameters of the nano-microstructures, simulations can also be performed according to the various parameters of the metasurface lens to obtain a simulation diagram of the working results of the metasurface lens. See Figures 15 to 19 . Based on parameters such as a radius of 400 um, a focal length of 800 um, an f-number of 1, an achromatic bandwidth of 5 um, a substrate height of 10 um, a substrate step number of 2, a width of the highest step of 556.5 um, a width of the lowest step of 121.75 um, and the structural parameters of the nano-microstructures, simulations are performed to test the performance of the metasurface lens.

[0292] See Figure 15 ,Figure 15 A graph showing the correspondence between each preset position of the metasurface lens provided in the embodiment of the present application and the PSF (Point Spread Function) of the metasurface lens in the x direction. The x direction is the direction along the radius of the substrate of the metasurface lens. Figure 15 In the graph, the horizontal axis represents each preset position of the metasurface lens, with the unit of um. The point with 0 in the horizontal axis represents the center of the metasurface lens. The vertical axis represents the light intensity, with the unit of V 2 / m 2 . When the abscissa is close to 0 um, the larger the corresponding ordinate, the higher the focusing efficiency of the metasurface lens. That is, when approaching the center of the metasurface lens, the greater the light intensity of the incident light, the higher the focusing efficiency of the metasurface lens.

[0293] As Figure 15 shown, for the metasurface lens with various parameters determined based on the method provided in the embodiment of the present application, when processing each incident light whose wavelength belongs to the preset working band, when the abscissa is close to 0 um, the corresponding ordinate is larger, that is, when approaching the center of the metasurface lens, the light intensity of the incident light is larger, that is, the light intensity of the incident light is concentrated in the central region of the metasurface lens. It can be seen that the focusing efficiency of the metasurface lens is relatively high.

[0294] Refer to Figure 16 , Figure 16 A graph showing the correspondence between the preset position along the principal optical axis direction of the metasurface lens provided in the embodiment of the present application and the PSF of the metasurface lens along the principal optical axis direction. Figure 16 In the graph, the horizontal axis represents the distance between the preset position along the principal optical axis direction of the metasurface lens and the center of the metasurface lens with the center of the metasurface lens as the origin, with the unit of um. The point with 0 in the horizontal axis represents the center of the metasurface lens. The vertical axis represents the light intensity, with the unit of V 2 / m 2 . Since the focal length of the metasurface lens is 800 um, that is, the distance between the focus of the metasurface lens and the center of the metasurface lens is 800 um, that is, the point with 800 um in the horizontal axis represents the focus of the metasurface lens. The closer the distance between the preset position along the principal optical axis direction of the metasurface lens and the center of the metasurface lens is to 800 um, the closer this preset position is to the focus of the metasurface lens. When the abscissa is close to 800 um, the larger the corresponding ordinate, that is, when this preset position is closer to the focus of the metasurface lens, the greater the light intensity of the incident light, then the focal length of the metasurface lens is closer to 800 um, that is, the smaller the focal length offset of the metasurface lens, and the higher the focusing efficiency of the metasurface lens.

[0295] As Figure 16As shown, for the metasurface lens whose various parameters are determined based on the method provided in the embodiments of the present application, when processing incident light with wavelengths belonging to a preset working band, the light intensity of the incident light is concentrated in the area where the height of the metasurface lens is 800 um. It can be seen that the focal length offset of the metasurface lens is small, and the focusing efficiency of the metasurface lens is high.

[0296] Correspondingly, referring to Figure 17 , Figure 17 is a graph showing the correspondence between the wavelength of the incident light and the focal length of the metasurface lens provided in the embodiments of the present application. As Figure 17 shown, Figure 17 the horizontal axis of is wave, and the vertical axis is focuslength. When the wavelength of the incident light belongs to 9 um - 14 um, the focal length of the metasurface lens belongs to 780 um - 800 um, and the offset from the desired focal length (i.e., 800 um) is less than 1%. That is, the focal length offset of the metasurface lens whose various parameters are determined based on the method provided in the embodiments of the present application is small.

[0297] Referring to Figures 18(a) to 18(g) . Figure 18(a) is a schematic diagram of the PSF of the incident light with a wavelength of 8 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(b) is a schematic diagram of the PSF of the incident light with a wavelength of 9 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(c) is a schematic diagram of the PSF of the incident light with a wavelength of 10 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(d) is a schematic diagram of the PSF of the incident light with a wavelength of 11 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(e) is a schematic diagram of the PSF of the incident light with a wavelength of 12 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(f) is a schematic diagram of the PSF of the incident light with a wavelength of 13 um at each preset position of the metasurface lens provided in the embodiments of the present application. Figure 18(g) is a schematic diagram of the PSF of the incident light with a wavelength of 14 um at each preset position of the metasurface lens provided in the embodiments of the present application.

[0298] Figures 18(a) to 18(g) In, the horizontal axis and the vertical axis represent each preset position of the metasurface lens. For each preset position, the lighter the color of the preset position, the greater the light intensity at that preset position. The greater the light intensity at the center of the metasurface lens and the smaller the light intensity at other positions except the center of the metasurface lens, the higher the focusing efficiency of the metasurface lens.

[0299] Based on Figures 18(a) to 18(g)It can be obtained that the light intensity of the incident light with a wavelength of 8 μm is small at the center of the metasurface lens, and the light intensity of the incident light with a wavelength of 8 μm is large at other preset positions except the center of the metasurface lens. The light intensity of the incident light with each wavelength in the preset working band is large at the preset position at the center of the metasurface lens, and the light intensity is small at other preset positions except the preset position at the center of the metasurface lens. That is, the focusing efficiency of the metasurface lens with various parameters determined based on the method provided in the embodiments of the present application is high.

[0300] See Figure 19 , Figure 19 which is a curve graph showing the correspondence between the wavelength of the incident light provided in the embodiments of the present application and the focusing efficiency of the metasurface lens. As Figure 19 shown, Figure 19 the abscissa of is wavelength, and the ordinate is the focusing efficiency of the metasurface lens. When the wavelength of the incident light does not belong to the preset working band, that is, when the wavelength is 8 μm, the focusing efficiency of the metasurface lens is less than 15%, that is, the focusing efficiency is small. When the wavelength of the incident light belongs to the preset working band, that is, when the wavelength belongs to 9 μm - 14 μm, the focusing efficiency of the metasurface lens is greater than 35%, that is, the focusing efficiency is high.

[0301] It can be seen that the focal length offset of the metasurface lens with various parameters determined based on the method provided in the embodiments of the present application is small, and the focusing efficiency is high. That is, the performance of the metasurface lens with various parameters determined based on the method provided in the embodiments of the present application is high.

[0302] Based on the same inventive concept as the above method for determining the parameters of the metasurface lens, the embodiments of the present application further provide a device for determining the parameters of a metasurface lens. See Figure 20 , Figure 20 which is a structural diagram of the device for determining the parameters of the metasurface lens provided in the embodiments of the present application. The device includes:

[0303] A required phase difference determination module 2001, configured to, for each preset position of the metasurface lens with parameters to be determined, determine the required phase difference of the incident light with two target wavelengths within the preset working band at this preset position based on the preset radius and the preset working band of the metasurface lens, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference;

[0304] A modulation phase difference determination module 2002, configured to, for each nano microstructure, obtain the modulation phase difference of this nano microstructure for the incident light with the two target wavelengths from the microstructure database, and obtain the maximum value among the modulation phase differences corresponding to each nano microstructure as the maximum modulation phase difference;

[0305] The substrate parameter determination module 2003 is configured to determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step based on the maximum required phase difference and the maximum modulation phase difference;

[0306] The substrate phase determination module 2004 is configured to calculate, for each step of the substrate, the difference between the maximum value of the required phase differences corresponding to the preset positions in the step and the maximum modulation phase difference, to obtain the substrate phase of the step;

[0307] The microstructure phase determination module 2005 is configured to calculate, for each preset position of the metasurface lens, the microstructure phase of the nano-microstructure at the preset position based on the required phase of the incident light of the two target wavelengths at the preset position and the substrate phase of the step to which the preset position belongs;

[0308] The microstructure parameter determination module 2006 is configured to determine, in the microstructure database, the structural parameters of the nano-microstructure that satisfy the microstructure phase corresponding to the preset position, to obtain the structural parameters of the nano-microstructure of the metasurface lens at the preset position.

[0309] Optionally, the required phase difference determination module 2001 is specifically configured to:

[0310] Calculate the required phases of the incident light of the two target wavelengths within the preset working band at the preset position according to a first preset formula;

[0311] Wherein, the first preset formula is:

[0312]

[0313] Wherein, represents the required phase, (x, y) represents the coordinates of a position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant;

[0314] Calculate the difference between the required phases of the incident light of the two target wavelengths at the preset position, to obtain the required phase difference of the incident light of the two target wavelengths at the preset position.

[0315] Optionally, the substrate parameter determination module 2003 is specifically configured to:

[0316] Calculate the quotient of the maximum required phase difference and the maximum modulation phase difference, and round up the calculation result to obtain the number of steps of the substrate;

[0317] For each step of the substrate, calculate the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step; wherein, the coefficient corresponding to a step represents the position of the step in the substrate.

[0318] Determine the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate.

[0319] Optionally, the substrate parameter determination module 2003 is specifically configured to:

[0320] Calculate the product of the maximum modulation phase difference and the coefficient corresponding to the step as the first phase parameter of the step.

[0321] Calculate the difference between the maximum required phase difference and the first phase parameter of the step to obtain the second phase parameter of the step.

[0322] Determine, from the preset positions of the metasurface lens, the preset position corresponding to the required phase difference that is the same as the second phase parameter of the step, to obtain the position of the edge of the step in the metasurface lens.

[0323] Determine the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and with the center of the metasurface lens as the center of the circle, to obtain the diameter of the circular region to which the step belongs.

[0324] If the step is the highest step in the substrate, determine the diameter of the circular region to which the step belongs as the width of the step.

[0325] If the step is not the highest step in the substrate, calculate the difference between the radius of the circular region to which the step belongs and the radius of the circular region to which the upper adjacent step belongs to obtain the width of the step.

[0326] Optionally, the substrate parameter determination module 2003 is specifically configured to:

[0327] Based on a second preset formula, determine the height of the substrate at the step according to the substrate phase of the step and the refractive index of the material of the substrate.

[0328] Wherein, the second preset formula is:

[0329]

[0330] Wherein, represents the substrate phase of the step, n represents the refractive index of the material of the substrate, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at the step.

[0331] Based on the parameter determination device of the metasurface lens provided in the embodiments of the present application, the parameters of the metasurface lens can be determined, that is, the number of steps of the substrate of the metasurface lens, the width of each step, the height of the substrate at each step, and the nano-microstructures at each preset position are determined. For the metasurface lens fabricated according to the determined parameters, the steps of the metasurface lens and the multiple nano-microstructures on its surface jointly perform dispersion on the incident light. That is, the dispersion of the incident light by the metasurface lens is the sum of the dispersion of the incident light by the substrate and the dispersion of the incident light by the nano-microstructures. Since the substrate of the metasurface lens is a stepped disk structure, that is, the substrate includes multiple steps, the dispersion of the incident light by the substrate is increased, and thus the dispersion of the incident light by the metasurface lens is increased. The dispersion of the incident light by the metasurface lens is positively correlated with the radius of the metasurface lens, the dispersion of the incident light by the metasurface lens is positively correlated with the numerical aperture of the metasurface lens, and the dispersion of the incident light by the metasurface lens is positively correlated with the bandwidth of the achromatic band of the metasurface lens. Then, when the dispersion of the incident light by the metasurface lens is increased, the radius, numerical aperture, and bandwidth of the achromatic band of the metasurface lens can be increased, that is, a metasurface lens with a relatively large radius, a relatively large numerical aperture, and a relatively large bandwidth of the achromatic band can be obtained.

[0332] The embodiments of the present application also provide an electronic device, such as Figure 21 shown, including:

[0333] A memory 2101 for storing a computer program;

[0334] A processor 2102, configured to implement the steps of the parameter determination method of any metasurface lens in the above embodiments when executing the program stored in the memory 2101.

[0335] And the above electronic device may further include a communication bus and / or a communication interface. The processor 2102, the communication interface, and the memory 2101 complete communication with each other through the communication bus.

[0336] The communication bus mentioned in the above electronic device may be a Peripheral Component Interconnect (PCI) bus or an Extended Industry Standard Architecture (EISA) bus, etc. This communication bus can be divided into an address bus, a data bus, a control bus, etc. For the sake of simplicity, only a thick line is shown in the figure, but it does not mean that there is only one bus or one type of bus.

[0337] The communication interface is used for communication between the above electronic device and other devices.

[0338] The memory may include a Random Access Memory (RAM), or may also include a Non-Volatile Memory (NVM), such as at least one disk memory. Optionally, the memory may also be at least one storage device located away from the aforementioned processor.

[0339] The aforementioned processor may be a general-purpose processor, including a Central Processing Unit (CPU), a Network Processor (NP), etc.; it may also be a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field-Programmable Gate Array (FPGA), or other programmable logic devices, discrete gate or transistor logic devices, discrete hardware components.

[0340] In another embodiment provided by the present application, there is also provided a computer-readable storage medium, in which a computer program is stored, and when the computer program is executed by a processor, the steps of any of the above parameter determination methods of the metasurface lens are implemented.

[0341] In another embodiment provided by the present application, there is also provided a computer program product containing instructions, which when run on a computer, causes the computer to execute any of the parameter determination methods of the metasurface lens in the above embodiments.

[0342] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware, or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the processes or functions described in the embodiments of the present application are generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable devices. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from one website, computer, server, or data center to another website, computer, server, or data center by wire (such as coaxial cable, optical fiber, digital subscriber line (DSL)) or wirelessly (such as infrared, wireless, microwave, etc.). The computer-readable storage medium may be any available medium that a computer can access, or a data storage device such as a server or data center that includes one or more integrated available media. The available medium may be a magnetic medium (such as a floppy disk, hard disk, magnetic tape), an optical medium (such as a DVD), or other storage media (such as a solid-state disk (SSD)).

[0343] It should be noted that in this document, relational terms such as first and second are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise", or any other variation thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device that includes a series of elements includes not only those elements but also other elements not explicitly listed, or also includes elements inherent to such process, method, article, or device. Without further limitation, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article, or device that includes the element.

[0344] Each embodiment in this specification is described in a related manner. The same or similar parts among the embodiments can be referred to each other, and the differences between each embodiment and other embodiments are emphasized. In particular, for the embodiments of the apparatus, electronic device, computer-readable storage medium, and computer program product, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments.

[0345] The foregoing are only the preferred embodiments of the present application and are not intended to limit the protection scope of the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present application are all included within the protection scope of the present application.

Claims

1. A metasurface lens, characterized in that, Comprising: A substrate and nano-microstructures; wherein, One side of the substrate is formed into a stepped disc structure that increases sequentially from the periphery to the center. The stepped disc structure includes at least one step, and a plurality of nano-microstructures are arranged on each step surface; the dispersion is jointly performed by each step and the plurality of nano-microstructures on its surface; the plurality of nano-microstructures perform focusing; the layout of the plurality of nano-microstructures arranged on any step is such that the number of nano-microstructures present in the cross-section of this step is multiple; the stepped disc structure is symmetric about the main optical axis; the dispersion of the metasurface lens on the incident light is: the sum of the dispersion of the incident light by the substrate and the dispersion of the incident light by the nano-microstructures; the substrate is a multi-layer structure, and the materials of each layer are different; each nano-microstructure is a multi-layer structure, and the materials used in different layers are different; for the same layer of each nano-microstructure, the materials used are the same; when the working band of the metasurface lens is the visible light band, a visible light antireflection film is provided on the side of the substrate away from the nano-microstructures, and / or a visible light antireflection film is provided on the side of the plurality of nano-microstructures away from the substrate; when the working band of the metasurface lens is the infrared band, an infrared antireflection film is provided on the side of the substrate away from the nano-microstructures, and / or an infrared antireflection film is provided on the side of the plurality of nano-microstructures away from the substrate.

2. The metasurface lens according to claim 1, wherein The working band of the metasurface lens is the visible light band; the material of the substrate is a material that is transparent to visible light, and the material of the substrate includes at least one of the following materials: silica, quartz glass, fused quartz, flint glass, optical glass; The material of the nano-microstructures is a material that is transparent to visible light, and the material of one nano-microstructure includes at least one of the following materials: silicon nitride, silica, tantalum pentoxide.

3. The metasurface lens according to claim 1, wherein The working band of the metasurface lens is the infrared band, the material of the substrate is a material that is transparent to infrared, and the material of the substrate includes at least one of the following materials: silicon-based glass materials, germanium-based glass materials, chalcogenide glass materials; The material of the nano-microstructures is a material that is transparent to infrared, and the material of one nano-microstructure includes at least one of the following materials: silicon-based glass materials, germanium-based glass materials, chalcogenide glass materials.

4. The metasurface lens according to any one of claims 1-3, characterized in that The structure of one nano-microstructure is any one of the following structures: cylinder, square column, cross, ring, square ring, cylinder inverse structure, square column inverse structure, cross inverse structure.

5. A method for determining the parameters of a metasurface lens, characterized in that For determining the parameters of the metasurface lens according to any one of claims 1-4, the method includes: For each preset position of the metasurface lens for which the parameter is to be determined, based on the preset radius and preset working band of the metasurface lens, determine the required phase difference of the incident light of two target wavelengths within the preset working band at this preset position, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference; For each nano-microstructure, obtain the modulation phase difference of this nano-microstructure for the incident light of the two target wavelengths from the microstructure database, and obtain the maximum value among the modulation phase differences corresponding to each nano-microstructure as the maximum modulation phase difference; Based on the maximum required phase difference and the maximum modulation phase difference, determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step; wherein, the method for determining the number of steps of the substrate is: calculate the quotient of the maximum required phase difference and the maximum modulation phase difference, and round up the calculation result to obtain the number of steps of the substrate; the method for determining the width of each step is: for each step of the substrate, based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to this step, calculate the width of this step; wherein, the coefficient corresponding to a step represents the position of this step in the substrate. For each step of the substrate, calculate the difference between the maximum value of the required phase differences corresponding to each preset position in this step and the maximum modulation phase difference, to obtain the substrate phase of this step. For each preset position of the metasurface lens, based on the required phases of the incident light of the two target wavelengths at this preset position and the substrate phase of the step to which this preset position belongs, calculate the microstructure phase of the nanostructure at this preset position. Determine the structural parameters of the nanostructure that satisfies the microstructure phase corresponding to this preset position in the microstructure database, to obtain the structural parameters of the nanostructure of the metasurface lens at this preset position.

6. The method according to claim 5, characterized in that, The determining the required phase difference of the incident light of the two target wavelengths within the preset working band at this preset position based on the preset radius and the preset working band of the metasurface lens includes: According to a first preset formula, calculate the required phases of the incident light of the two target wavelengths within the preset working band at this preset position. Wherein, the first preset formula is: Among them, represents the required phase, (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, and r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant; Calculate the difference between the required phases of the incident light of the two target wavelengths at this preset position, to obtain the required phase difference of the incident light of the two target wavelengths at this preset position.

7. The method according to claim 5, wherein The method for determining the height of the substrate at each step is: For each step of the substrate, based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to this step, calculate the width of this step; wherein, the coefficient corresponding to a step represents the position of this step in the substrate. Based on the substrate phase of this step and the refractive index of the material of the substrate, determine the height of the substrate at this step.

8. The method according to claim 7, wherein The calculating the width of this step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to this step includes: Calculate the product of the maximum modulation phase difference and the coefficient corresponding to this step, as the first phase parameter of this step. Calculate the difference between the maximum required phase difference and the first phase parameter of this step, to obtain the second phase parameter of this step. From each preset position of the metasurface lens, determine the preset position corresponding to the required phase difference that is the same as the second phase parameter of this step, to obtain the position of the edge of this step in the metasurface lens. Determine the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and the center of the metasurface lens as the center of the circle, and obtain the diameter of the circular region to which the step belongs; If the step is the highest step in the substrate, determine the diameter of the circular region to which the step belongs as the width of the step; If the step is not the highest step in the substrate, calculate the difference between the radius of the circular region to which the step belongs and the radius of the circular region to which the adjacent upper step belongs, and obtain the width of the step.

9. The method according to claim 7, wherein The determining the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate includes: Based on a second preset formula, determine the height of the substrate at the step according to the substrate phase of the step and the refractive index of the material of the substrate; Wherein, the second preset formula is: Wherein, represents the substrate phase of the step, n represents the refractive index of the material of the substrate, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at the step.

10. A parameter determination device for a metasurface lens, characterized in that, For determining the parameters of the metasurface lens according to any one of claims 1-4, the apparatus includes: A required phase difference determination module, configured to, for each preset position of the metasurface lens for which parameters are to be determined, based on the preset radius and preset working band of the metasurface lens, determine the required phase difference of the incident light of two target wavelengths within the preset working band at the preset position, and obtain the maximum value among the required phase differences corresponding to each preset position as the maximum required phase difference; A modulation phase difference determination module, configured to, for each nano microstructure, obtain from the microstructure database the modulation phase difference of the nano microstructure for the incident light of the two target wavelengths, and obtain the maximum value among the modulation phase differences corresponding to each nano microstructure as the maximum modulation phase difference; A substrate parameter determination module, configured to determine the number of steps of the substrate of the metasurface lens, the width of each step, and the height of the substrate at each step based on the maximum required phase difference and the maximum modulation phase difference; wherein, the way to determine the number of steps of the substrate is: calculate the quotient of the maximum required phase difference and the maximum modulation phase difference, and round up the calculation result to obtain the number of steps of the substrate; the way to determine the width of each step is: for each step of the substrate, calculate the width of the step based on the maximum required phase difference, the maximum modulation phase difference, and the coefficient corresponding to the step; wherein, the coefficient corresponding to a step represents the position of the step in the substrate; A substrate phase determination module, configured to, for each step of the substrate, calculate the difference between the maximum value among the required phase differences corresponding to each preset position in the step and the maximum modulation phase difference, and obtain the substrate phase of the step; A microstructure phase determination module, configured to, for each preset position of the metasurface lens, calculate the microstructure phase of the nano microstructure at the preset position based on the required phase of the incident light of the two target wavelengths at the preset position and the substrate phase of the step to which the preset position belongs; A microstructure parameter determination module, configured to determine the structural parameters of the nano microstructure that satisfies the microstructure phase corresponding to the preset position in the microstructure database, and obtain the structural parameters of the nano microstructure at the preset position of the metasurface lens.

11. The device according to claim 10, characterized in that, The demand phase difference determination module is specifically configured to: Calculate the demand phases of the incident lights of two target wavelengths within the preset working wavelength band at the preset position according to a first preset formula; Wherein, the first preset formula is: Among them, represents the required phase, (x, y) represents the coordinates of a preset position in the metasurface lens, λ represents the target wavelength, f represents the focal length of the metasurface lens, and r represents the radius coordinate corresponding to the preset position with coordinates (x, y) in the polar coordinate system, is a preset constant; Calculate the difference between the demand phases of the incident lights of the two target wavelengths at the preset position to obtain the demand phase difference of the incident lights of the two target wavelengths at the preset position.

12. The device according to claim 10, characterized in that, The substrate parameter determination module is specifically configured to: Determine the height of the substrate at the step based on the substrate phase of the step and the refractive index of the material of the substrate.

13. The device according to claim 12, characterized in that, The substrate parameter determination module is specifically configured to: Calculate the product of the maximum modulation phase difference and the coefficient corresponding to the step as the first phase parameter of the step; Calculate the difference between the maximum demand phase difference and the first phase parameter of the step to obtain the second phase parameter of the step; Determine, from the preset positions of the metasurface lens, the preset position corresponding to the demand phase difference that is the same as the second phase parameter of the step to obtain the position of the edge of the step in the metasurface lens; Determine the diameter of a circle with the distance between the edge of the step and the center of the metasurface lens as the radius and with the center of the metasurface lens as the center of the circle to obtain the diameter of the circular region to which the step belongs; If the step is the highest step in the substrate, determine the diameter of the circular region to which the step belongs as the width of the step; If the step is not the highest step in the substrate, calculate the difference between the radius of the circular region to which the step belongs and the radius of the circular region to which the upper adjacent step of the step belongs to obtain the width of the step.

14. The device according to claim 12, characterized in that, The substrate parameter determination module is specifically configured to: Determine the height of the substrate at the step based on a second preset formula according to the substrate phase of the step and the refractive index of the material of the substrate; Wherein, the second preset formula is: Among them, represents the substrate phase of the step, n represents the refractive index of the material of the substrate, λ1 and λ2 respectively represent the two target wavelengths, and h represents the height of the substrate at the step.

15. An electronic device, characterized in that, Including: A memory for storing a computer program; A processor, when executing the program stored on the memory, implements the method according to any one of claims 5-9.

16. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program, and when the computer program is executed by the processor, it implements the method according to any one of claims 5-9.

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