Superlens structure of lens and optical system of lens with same

Abstract

The invention relates to a super-lens structure of a lens and an optical system of the lens with the super-lens structure. The super lens structure of the lens comprises a light-transmitting substrate; the nano structure is arranged on the surface of at least one side of the substrate, and comprises a plurality of nano units based on tetragonal or hexagonal units; the plurality of tetragonal or hexagonal unit-based nanocells form one or more tetragonal or hexagonal ring-shaped nanocell groups and gaps formed between the nanocell groups. Thus, through the optical structure based on more different periods rather than a single fixed period, smaller structural choices can be provided for regions with high phase gradients, so that more structural choices and higher modulation capability can be realized.

Description

Technical Field

[0001] This application relates to the field of optical technology, and more specifically, to a superlens structure for a lens and an optical system having the same. Background Technology

[0002] Currently, TOF (Time-of-Flight) lenses are used in many fields, such as mobile phones, security monitoring, virtual reality, augmented reality, and autonomous driving. Due to the limitations of the device's size, TOF lenses are increasingly developing towards miniaturization, lightweight design, and low cost. Existing TOF modules typically contain at least three lenses in their receiving module, which increases the overall height of the receiving module and thus the cost. Furthermore, multiple spherical lenses or several aspherical lenses are used to correct related aberrations, but this also introduces many negative effects. Therefore, it is difficult for existing TOF lenses to achieve large apertures and controllable aberrations while maintaining a slim and lightweight design and low cost.

[0003] Therefore, this application aims to provide an improved lens optical structure. Summary of the Invention

[0004] This application provides a superlens structure for a lens and an optical system having the same. By using an optical structure based on more different periods rather than a single fixed period, it can provide smaller structural choices for high phase gradient regions and larger structural choices for low phase gradient regions, compared to a fixed-period design, thereby achieving more structural choices and higher modulation capabilities.

[0005] According to one aspect of this application, a superlens structure for a lens is provided, comprising: a light-transmitting substrate; and a nanostructure disposed on at least one side surface of the substrate, wherein the nanostructure comprises a plurality of tetragonal or hexagonal nanounits, the plurality of tetragonal or hexagonal nanounits forming one or more tetragonal or hexagonal ring-shaped nanounit groups and gaps formed between the nanounit groups.

[0006] In the superlens structure of the above lens, the diameter of the ring shape of the plurality of tetragonal or hexagonal ring-shaped nanounit groups is different from the lattice of the nanounits in the nanounit groups based on tetragonal or hexagonal units.

[0007] In the superlens structure of the aforementioned lens, the nanounits in the nanounit group are coaxially distributed in a tetragonal or hexagonal pattern.

[0008] In the superlens structure of the above-described lens, the widths of at least some of the gaps are not equal, and / or the heights of the nanounits are equal.

[0009] In the superlens structure of the aforementioned lens, the nanounits belonging to different ring-shaped nanounit groups have the same height and different lattice sizes.

[0010] The superlens structure of the lens described above further includes: one or more film layers disposed on the opposite surface of the substrate to the nanostructure.

[0011] In the superlens structure of the above-mentioned lens, the nanounit, the substrate and the film are made of one of the following materials: photoresist, silicon nitride, titanium oxide, single crystal silicon, polycrystalline silicon, amorphous silicon, gallium nitride (GaN), hafnium dioxide (HfO2), halide crystal, sapphire and other oxide crystals, quartz, chalcogenide crystal, glass, plastic or semiconductor material.

[0012] In the superlens structure of the aforementioned lens, the gap is air, or a material with a different refractive index than the material of the annular nanounit group.

[0013] In the aforementioned superlens structure of the lens, at least two nanounits in the nanostructure have a diameter s n Period size P m , or position r n They are not equal, the period size P m The position r is the side length of the tetragonal or hexagonal unit corresponding to the nanounit. n It is the distance from the center of the nanounit to the center of the superlens structure.

[0014] In the superlens structure of the above lens, when the nanostructure transmits visible light, the height H of the nanostructure is greater than or equal to 100 nm and less than or equal to 1500 nm, the spacing between adjacent nanounits is greater than or equal to 40 nm and less than or equal to 850 nm, and the minimum size of the nanounit is 30 nm.

[0015] In the superlens structure of the above lens, when the nanostructure transmits infrared light in the 820nm to 880nm band, the height H of the nanostructure is greater than or equal to 100nm and less than or equal to 8μm, the spacing between adjacent nanounits is greater than or equal to 50nm and less than or equal to 2μm, and the minimum size of the nanounit is 50nm.

[0016] According to another aspect of this application, an optical system for a lens is provided, comprising, starting from the object side: a functional layer; an aperture stop; and, as described above, a superlens structure for a lens.

[0017] In the optical system of the aforementioned lens, the functional layer includes one or more of the following: a glass cover plate, a polarizing half-wave plate, a quarter-wave plate, an anti-reflective film, or an anti-reflective film.

[0018] In the optical system of the aforementioned lens, the aperture is attached to the surface of the functional layer, or it is a light-transmitting aperture formed by a coating integrated on one side of the functional layer based on semiconductor technology.

[0019] The optical system of the aforementioned lens further includes a detector, which is an imaging chip.

[0020] In the optical system of the above lens, the aperture stop has a size of 1.24 mm, the distance from the aperture stop to the side surface of the substrate of the superlens structure opposite to the nanostructure is 1.16 mm, the thickness of the substrate is 0.3 mm, and the distance from the detector to the surface of the nanostructure is greater than 1.5 mm and less than 2 mm.

[0021] The superlens structure of the lens and the optical system having the lens provided in this application embodiment can provide smaller structural choices for regions with high phase gradients by using optical structures based on more different periods rather than a single fixed period, thereby achieving more structural choices and higher modulation capabilities. Attached Figure Description

[0022] Various other advantages and benefits of this application will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. It is obvious that the drawings described below are merely some embodiments of this application, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. Furthermore, the same reference numerals denote the same parts throughout the drawings.

[0023] Figure 1 The illustration shows a schematic diagram of a periodically fixed tetragonal and hexagonal arrangement of a lens superlens structure according to an embodiment of the present application.

[0024] Figure 2 The illustration shows a schematic diagram of a tetragonal and hexagonal arrangement of a lens superlens structure with a non-fixed period according to an embodiment of the present application.

[0025] Figure 3 The illustration shows a schematic diagram of a lens superlens structure according to an embodiment of the present application, in which a mirror region is formed through a design region.

[0026] Figure 4 The illustration shows a schematic diagram of a square variable-period arrangement of a lens superlens structure according to an embodiment of the present application, formed by rotating the design region and the mirror region.

[0027] Figure 5The illustration shows a schematic diagram of a hexagonal variable periodic arrangement of a lens superlens structure according to an embodiment of the present application, formed by rotation of the design region and the mirror region.

[0028] Figure 6 The illustration shows a schematic diagram of an optical system having a superlens structure with consideration of process constraints for the lens according to an embodiment of this application.

[0029] Figure 7 The illustration shows a target design schematic diagram of an optical system having a superlens structure of a lens according to an embodiment of this application.

[0030] Figure 8A and Figure 8B The diagrams illustrate the optimized amplitude and phase of the superlens structure of the lens according to embodiments of this application for both tetragonal and hexagonal configurations.

[0031] Figure 9 The illustration shows the results of an optimization analysis of the tetragonal variable-period superlens design of the superlens structure of the lens according to an embodiment of this application.

[0032] Figure 10 The illustration shows a schematic diagram of another design result of an optical system having a superlens structure of a lens according to an embodiment of this application.

[0033] Figure 11 The diagram shows... Figure 10 The diagram shows a schematic of the design MTF of an optical system for a lens having a superlens structure according to an embodiment of this application.

[0034] Figure 12 The diagram shows... Figure 10 The diagram shows the relative illumination effect of an optical system having a superlens structure according to an embodiment of this application. Detailed Implementation

[0035] Hereinafter, exemplary embodiments according to this application will be described in detail with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of this application, and not all embodiments of this application. It should be understood that this application is not limited to the exemplary embodiments described herein.

[0036] The optical system of a traditional TOF module, composed of several lenses, has high requirements for assembly and alignment, especially for aspherical lenses, which have even higher requirements for assembly alignment and processing. In addition, the size and weight limitations of this type of refractive index modulated optical system cannot guarantee that it will be extremely thin and integrable.

[0037] For optical metasurfaces, they have evolved into a new and reliable technology for miniaturizing and planarizing traditional optical systems. Their powerful polarization phase and spectral modulation capabilities are increasingly enabling applications such as cylindrical lenses, spatial lattices, and ultrathin lenses. The high degree of freedom in phase control also allows metasurfaces to offer modulation capabilities far exceeding those of a single lens in design scenarios, surpassing the modulation freedom and capabilities of individual spherical or aspherical lenses.

[0038] Based on this, embodiments of this application provide a superlens structure for a lens based on a variable-period unit design, along with corresponding design and optimization schemes. Compared to the traditional fixed-period unit design, the variable-period unit design of the lens according to embodiments of this application can be based on a wider range of different period databases, rather than a single fixed-period database. Importantly, the variable-period design can provide smaller or larger structural choices for regions with high or low phase gradients, implying more structural options and higher modulation capabilities. Specifically, the superlens structure scheme of the lens according to embodiments of this application is applicable to all nanostructures with square and hexagonal periods (including but not limited to nanocylinders, nanoprisms, nanocross structures, nanohollow structures, etc.). Furthermore, the optimized design scheme of the superlens structure of the lens according to embodiments of this application can also design nanoring-shaped superlenses.

[0039] Figure 1 The illustration shows a schematic diagram of a periodically fixed tetragonal and hexagonal arrangement of a lens superlens structure according to an embodiment of the present application. Figure 2 The illustration shows a schematic diagram of a tetragonal and hexagonal arrangement of a lens superlens structure with a non-fixed period according to an embodiment of the present application. Figure 3 The illustration shows a schematic diagram of a lens superlens structure according to an embodiment of the present application, in which a mirror region is formed through a design region. Figure 4 The illustration shows a schematic diagram of a square variable-period arrangement of a lens superlens structure according to an embodiment of the present application, formed by rotating the design region and the mirror region. Figure 5 The illustration shows a schematic diagram of a hexagonal variable periodic arrangement of a lens superlens structure according to an embodiment of the present application, formed by rotation of the design region and the mirror region.

[0040] like Figures 1 to 5As shown, the superlens structure of the lens according to an embodiment of this application has a superlens design based on tetragonal or hexagonal units with variable periodicity and considering angular characteristics, and the superlens structure of the lens may have an approximately ring-shaped design with variable periodicity. Specifically, the superlens structure of the lens includes a light-transmitting substrate and a nanostructure disposed on at least one surface of the substrate. The nanostructure includes a plurality of tetragonal or hexagonal ring-shaped nanounits and gaps formed between the nanounits. The diameters and lattice sizes of the nanounits included in the superlens structure of the lens are different. The nanounits are preferably coaxially tetragonal or hexagonal, and at least one of the widths of the gaps and the diameters of the nanounits is not equal. Here, the nanounits within the lattice can be various types of structural units, such as nanopillars, nanopores, nanorings, cross-shaped, loop-shaped, rectangular, and other different nanostructures.

[0041] That is, the superlens structure of the lens according to the embodiments of this application includes: a light-transmitting substrate; and a nanostructure disposed on one side surface of the substrate, wherein the nanostructure includes a plurality of nanounits based on tetragonal or hexagonal units, the plurality of nanounits based on tetragonal or hexagonal units forming one or more tetragonal or hexagonal ring-shaped nanounit groups, and gaps formed between the nanounit groups.

[0042] Furthermore, in the superlens structure of the lens according to the embodiments of this application, the ring diameter of the plurality of tetragonal or hexagonal annular nanounit groups and the lattice of the nanounits in the nanounit groups based on tetragonal or hexagonal units are not the same.

[0043] Furthermore, in the superlens structure of the lens according to the embodiments of this application, the nanounits in the nanounit group are coaxially tetragonal or hexagonal distributed.

[0044] Furthermore, in the superlens structure of the lens according to the embodiments of this application, the widths of the at least some gaps are not equal, and / or the heights of the nanounits are equal.

[0045] Generally speaking, the phase distribution of the lens's superlens structure can be defined because the light phases of the gaps at different positions and the corresponding nanounits are different. Preferably, in the embodiments of this application, the nanounits are nanounits of different sizes but with different periods, and the corresponding gaps are also of the same height. Nanounits of equal height are beneficial for processing to a certain extent and improve processing efficiency.

[0046] Furthermore, optionally, the surface of the substrate of the lens's superlens structure opposite to the nanostructure also includes a coating layer. The substrate with the coating layer includes polarization and spectral selection functions or other functions such as anti-reflection and anti-reflection. Of course, those skilled in the art will understand that the lens's superlens structure may also not include the coating layer, thus lacking this function. For example, polarization and spectral selection functions can be achieved based on a substrate of a polarizer, a half-wave plate, or a quarter-wave plate and a filter film based on the principle of multilayer film interference, thereby enabling the transmission of light of different wavelengths and polarizations, or the anti-reflection and anti-reflection functions of the multilayer film.

[0047] In the embodiments of this application, the substrate material can be various materials, such as silicon-based materials like Si, SiO2, or quartz, or even polarization-eliminating polarizers such as integrated metal wire grids, or devices capable of polarization selection such as 1 / 2 or 1 / 4 waveplates, as long as they meet their transmittance and polarization requirements in the operating wavelength band. That is, the substrate and film layer can be configured to transmit light in specific wavelength and polarization bands. Furthermore, the substrate thickness can be designed according to actual optical path requirements. The materials of the tetragonal or hexagonal annularly distributed nanostructures, the substrate, and the coating layer can be one of the following: photoresist, silicon nitride, titanium oxide, single-crystal silicon, polycrystalline silicon, amorphous silicon, gallium nitride (GaN), hafnium dioxide (HfO2), halide crystals, sapphire and other oxide crystals, quartz, chalcogenide crystals, glass (e.g., oxides, chalcogenides, and other types of glass), plastics, or semiconductor materials, etc.

[0048] That is, in the superlens structure of the lens according to the embodiments of this application, the superlens structure of the lens further includes one or more film layers disposed on the opposite surface of the substrate to the nanostructure. Furthermore, in other examples, the film layer may also be disposed on the same side surface as the nanostructure.

[0049] Therefore, the superlens structure of the lens according to embodiments of this application includes a substrate and a tetragonal or hexagonal annularly distributed nanostructure on the substrate, as well as one or more film layers. The tetragonal or hexagonal annularly distributed nanostructure comprises multiple groups of nanounits distributed in an approximately ring shape, and the gaps formed between the annularly distributed nanounit groups can be air or filled with a material with a different refractive index than the approximately ring-shaped material, such as PMMA or photoresist. In one example, the nanounits can be implemented as air, surrounded by a material with a different refractive index than air; that is, nanounits in the form of nanopores are formed on one side of the superlens. In embodiments of this application, the arrangement and design of the nanopores can be the same as the arrangement and design of the nanounits as described above.

[0050] It should be noted that, let the height of the approximately ring-shaped nanounits at different positions be h, preferably designed with the same height, that is, at least two nanounits have a diameter s. n Period size P m , or position r n They are not equal. In the design parameters of this application embodiment, the position of the nanounit refers to the distance r from the center of the nanounit to the center O. n Duty cycle α n This refers to the periodicity P of the corresponding position of the nanounit. m With nanounit diameter s n The proportion α n =s n / P m Through different positions r i N tetragonal or hexagonal ring-shaped nanounits (i = 1, 2, ..., n-1, n, ..., N), wherein adjacent nanounits with the same period form a ring-shaped nanounit group. The structure of each tetragonal or hexagonal ring-shaped nanounit group consists of nanounits with the same period and a diameter s. n A ring structure composed of different nanounit combinations, wherein the period size P m and duty cycle α n They can be the same or different; and, the nanounit groups of different periods extend radially outward to form the phase of the desired superlens.

[0051] In this embodiment, all parameters of the lens's superlens structure are free variables, that is, r at different positions... j The periodicity P of the tetragonal or hexagonal ring-shaped nanounits at the location m and nanounit diameter s n The values ​​can be unequal; the actual values ​​are calculated based on the phase and amplitude requirements of the superlens, while the phase distribution of the superlens is calculated based on the requirements of the superlens in the optical system. That is, s at different positions... n They may be equal or unequal, and their period P m Similarly, the periods P may be equal or unequal. This also means that compared to traditional fixed-period nanostructure designs, the period P of this design is... m It also provides design freedom; for positions with small phase gradient changes, a larger structural size can be used to achieve greater process compatibility and higher design freedom. In the embodiments of this application, the design system of the lens's superlens structure has 3*N+1 degrees of freedom, that is, each tetragonal or hexagonal annularly distributed nanostructure has three design degrees of freedom during the optimization process: position r. n Period size P m and nanounit diameter sn The total design degrees of freedom for N tetragonal or hexagonal ring-shaped nanostructures is 3*N. Adding the lens thickness, which represents one design degree of freedom, the total is 3*N+1 degrees of freedom. In the embodiments of this application, the nanounit group and the corresponding nanounit lattice (e.g., Figure 4 The square and Figure 5 Within the hexagonal shape (as shown in the image), it can be considered a monolithic structure, where the thickness of the nanounits is on the order of the wavelength of the working band, approximately 1 / 10 to 10 times the wavelength. For example, for 850nm light, the thickness of the nanounits is less than or equal to 8μm (unit: micrometer), and its thickness can range from 0.085μm to 8μm. The nanostructures, distributed in tetragonal or hexagonal rings, act as a superlens, while the substrate thickness supports these ring-shaped nanostructures.

[0052] Therefore, in the superlens structure of the lens according to the embodiments of this application, at least two nanounits have a diameter s n Period size P m , or position r n They are not equal, wherein the period size P m The position r is the side length of the tetragonal or hexagonal unit corresponding to the nanounit. n It is the distance from the center of the nanounit to the center of the superlens structure.

[0053] For the tetragonal and hexagonal designs of the superlens structure of the lens according to the embodiments of this application, the design principle is universal and applicable to any metaatomic structure and wavelength range to meet the design and application requirements of various angular performance applications. This design concept can be quickly extended to polarizing lens design and even polarization-insensitive superlens design, and a variety of metasurface material systems can be selected for the required wavelength range.

[0054] The superlens structure of the lens according to the embodiments of this application can be designed using a full-link simulation method. First, microscopic simulation is performed based on Maxwell's equations, using methods such as the finite element method (FEM), finite-difference time-domain (FDTD), modal analysis, and strictly coupled-wave method (RCWA). For the optical system, Kirchhoff diffraction integral and Rayleigh-Sommerfeld diffraction theory can be used for optical system simulation. At the subwavelength scale, microscopic simulation can be used to design and model the tetragonal or hexagonal ring-shaped micro / nano structures in the metasurface to obtain the desired optical response. At the optical system level, the focusing, oblique incidence, and design tolerance characteristics of the entire superlens can be verified using the microscopic simulation results and appropriate methods, thereby enabling optical design and optimization of the entire superlens.

[0055] The following describes a design method for a superlens structure of a lens according to an embodiment of this application.

[0056] First, it is necessary to calculate the database of corresponding tetragonal or hexagonal toroidal distributions of nanounits. For each tetragonal or hexagonal toroidal distribution of nanounits...

[0057] The design parameters for the column structure are (θ) j s j P j , t j ), where θ j It is the angle of incidence, s j It is the diameter of the nanounit, P j It is the edge length of the nanounit, i.e., the periodic parameter, t j The thickness of the superlens structure is given by the simulation analysis result (I j , φ j |θ j s j P j , t j ), where I j It is light intensity, φ j |θ j This indicates that at the incident angle θ j The phase below, i.e., phase φ j .

[0058] It should be noted that the light intensity I here is... j and phase φ jThe phase φ is calculated by diffracting the unit phase from the near field to the far field and then back to the near field from the far field. It can also be obtained directly through simulation. It should be noted that the far field here refers to a distance greater than one wavelength from the propagation distance, where the light field is in a stable propagation state. j and amplitude I j Unaffected by evanescent wave interference. Designed separately, taking 850nm as an example, the thickness t was obtained through large-scale simulations. j = ...400nm, 450nm and 500nm... different periodicity and nanometer unit diameter parameters s j and periodic parameter P j Simulation results of tetragonal or hexagonal ring-shaped nanostructures G{I j , φ j |θ j s j P j , t j}

[0059] First, the initial phase profile of the metasurface is obtained under ideal conditions based on diffraction calculations. This profile is represented in polynomial form by the nanostructures with tetragonal or hexagonal ring distribution on the back surface of the substrate. The ideal phase is divided into two parts. in For the initial phase, The perturbation term is optimized for the target scene performance. Based on the above design concept, the operating wavelength is designed to be λ, the desired focal length is F, the radius of the superlens is designed to be R, and the position radius r of each nanounit in the superlens is designed, where r takes a value from 0 to R.

[0060]

[0061] Based on this, an optimized phase is superimposed. This phase is represented by an even-degree polynomial, with the highest power being 20. Its expression is as follows: a j These are the polynomial coefficients, and their values ​​are shown in Table 1 below.

[0062]

[0063] This result serves as the target optimization value for the superlens:

[0064]

[0065] Iterative optimization is required to optimize the operation of the actual optical unit. The optimization will consider different values ​​for metasurface thickness, such as t. j = [...400nm, 450nm, 500nm...] and different overall transmittance A of the superlens lensThe superlenses with dimensions [0.1, 0.2, ..., 0.9, 1] are independently designed and balanced. Based on the complex field information of each design, the optical properties of the light field modulation are calculated and analyzed, such as the imaging MTF, relative illumination RI, spherical aberration, and other errors. The optimal thickness and overall transmittance design parameters are then optimized iteratively. The design flow for the lens device corresponding to each design parameter can start from the starting radius r0 of the metasurface; in this example, r0 can be simply assumed to be 0. The degradation factor scoFe(A) of each design is analyzed. lens , t i For any radius r j (r j ≤R). For this location, the degradation factor is expressed as:

[0066]

[0067] Among them (I) k , φ k θ k s k P k , t k The representative incident light intensity is a unit amplitude and the incident angle is θ. k When irradiated at this point, the period parameter is P. k and a diameter of s k And the thickness is t k The amplitude of the incident light becomes I after modulation by the tetragonal and hexagonal nanostructures. k Its phase becomes φ k It should be specifically noted that in this design, θ(r) j The parameter θ represents the angle of the principal ray of the incident light at different locations. For the same location, there may be multiple angles for the ray. Here, we can consider the angle θ... k Given a weighted value α(θ) k The target angle is optimized numerically. Thus, the following formula is optimized:

[0068]

[0069] This allows us to obtain nanounits that exhibit the best amplitude and phase characteristics under this angular feature.

[0070] in:

[0071]

[0072] It indicates that the thickness in the current database is t. i And the angle of the incident ray is θ(r) j The results of all tetragonal and hexagonal modulated optical fields. Where θ(r) j) represents the result of discretizing the incident angle in 5° increments. Where s F P F The width of the lattice and the tetragonal or hexagonal ring-shaped distribution of nanostructures are limited by process technology. i This represents the thickness of the designed superlens structure. r0 indicates the initial position of the lens design, r j It is the distance relative to the center of the designed superlens device during the design iteration process. φ j The desired design of the superlens at position r j The design phase at that point. θ(r) j ) is located in the system at r j The design analysis angle corresponding to the unit of the superlens. A lens The average intensity is the desired intensity of the superlens designed based on the actual unit characteristics. Mask(r) is the amplitude distribution of the desired superlens. Φ lens (r) represents the desired phase distribution of the superlens. I obj This is the complex amplitude of the desired superlens design. j g j In the design position r j At this location, the thickness is t i The incident light angle is θ(r) j ), based on database G{I k , φ k |θ k =θ(r) j ), s k g k , t k =t i The I that best meets the current design expectations obj =A lens Φ lens (r j The modulation requirements of nanounits and their lattice parameters, width P j and its diameter parameter s j Finally, based on the score(A) lens , t i Choose the best A. lens , t i The parameters are then used to obtain the optimal superlens design scheme and to perform optical analysis and verification.

[0073] It should be noted that the phase design optimization of the lens superlens structure according to the embodiments of this application takes into account the limitations of the actual simulated light intensity, working angle, and process parameters of the metasurface unit. This optimization can be used, especially for the realization of superlens functions with large FOVs, and the design freedom of variable period can increase the number of available unit selections. It should be noted that, for example, in the design of a tetragonal or hexagonal periodic structure, each period contains corresponding nano-units. In this case, the optimization region must be able to find the minimum optimization region by rotational symmetry, for example... Figure 2 The optimization regions for the square and hexagonal regions are defined, and then the corresponding r is calculated according to the positions indicated by the arrows. n and according to Φ lens (r) Calculate the position r corresponding to this structure. n The optimization objective is determined, and the optimization design is carried out according to the degradation factor. After designing the optimization region, the optimization region can be extended to the entire plane based on mirror and rotation operations to obtain the corresponding superlens design.

[0074] When the overall structure formed by multiple nanostructures needs to be transparent to visible light, the height H of the nanostructure is greater than or equal to 100 nm and less than or equal to 1500 nm, the spacing between adjacent nanostructures (i.e., the distance between the centers of two adjacent nanostructures) is greater than or equal to 40 nm and less than or equal to 850 nm, and the minimum size of the nanostructure (diameter, ring width, or minimum spacing between two adjacent nanostructures, etc.) can be 30 nm. For example, the height H of the nanostructure can be 100 nm, 200 nm, 300 nm, 400 nm, 500 nm, 600 nm, 700 nm, 800 nm, 900 nm, 1000 nm, 1100 nm, 1200 nm, 1300 nm, 1400 nm, or 1500 nm, or any other value within this range. For example, the spacing between adjacent nanostructures is 40 nm, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, or 650 nm, or any other value within this range. That is, the thickness and period of the nanounit (the spacing between adjacent nanostructures) are on the order of the wavelength of the working band, approximately 1 / 10 to 10 times the wavelength.

[0075] When the overall structure formed by multiple nanostructures needs to transmit infrared light in the 820nm–880nm wavelength band, the height H of the nanostructure is greater than or equal to 100nm and less than or equal to 8μm, the spacing between adjacent nanostructures is greater than or equal to 50nm and less than or equal to 2μm, and the minimum size of the nanostructure (diameter, or minimum spacing between two adjacent nanostructures, etc.) can be 50nm. For example, the height H of the nanostructure can be any other value within the range of 100nm, 150nm, 200nm, 250nm, 500nm, 750nm, 1μm, 1.5μm, 2μm, 2.5μm, 3μm, 3.5μm, 4μm, 6.5μm, 8μm, etc. For example, the spacing or size between adjacent nanostructures can be 50nm, 100nm, 150nm, 200nm, 250nm, 300nm, 350nm, 400nm, 450nm, 500nm, 750nm, 1um, 1.5μm, 2μm, or any other value within that range.

[0076] For a lens having a superlens structure according to an embodiment of this application, its optical system can be as follows: Figure 6 As shown. Figure 6 The illustration shows a schematic diagram of an optical system having a superlens structure considering process constraints, based on an embodiment of the lens according to this application. For example... Figure 6As shown, the optical system requires a relative illumination (RI) > 0.6 and a modulation transfer function (MTF) > 0.6@10lp / mm at different incident angles (±30°). According to an embodiment of this application, the optical system includes a superlens structure as described above, a functional layer, and an aperture stop. The functional layer, aperture stop, and superlens are sequentially arranged starting from the object side. The functional layer can be implemented as a glass cover plate to protect the entire optical system. Alternatively, the functional layer can be a polarizing plate, a half-wave plate, or a quarter-wave plate, or other polarization-limiting materials, or an anti-reflective or anti-reflective film. The aperture stop can optionally be attached to the surface of the functional layer, or it can be a light-transmitting aperture formed by a coating integrated on one side of the functional layer based on semiconductor technology. Through the modulation of the aperture stop and the superlens, incident light at different angles can be modulated by the supersurface in different regions, ensuring that the modulation capability of the supersurface can be individually optimized for the incident light at that angle, and selecting a structure with better performance. Furthermore, the optical system may include a support assembly, on which the functional layer, the aperture, and the superlens are sequentially disposed. Furthermore, the optical system may also include a detector, which may be a CMOS chip, a CCD chip, etc. The aperture allows a portion of the large-angle incident light to be modulated within the structure of other regions of the metasurface. In one example, the aperture size is designed to be 1.24 mm, the distance from the aperture to the coating layer is 1.16 mm, the thickness of the substrate containing the coating layer is 0.3 mm, and the distance from the detector to the metasurface is greater than 1.5 mm and less than 2 mm.

[0077] That is, Figure 6 The illustration shows an optical system of a lens based on a superlens structure of a lens according to an embodiment of the present application. The functional layer and the coating layer can respectively enable the selection of the polarization and transmission band of the incident light. The aperture can be coated on the functional layer or separated from the functional layer. The material of the functional layer can be a material such as quartz glass, and its thickness can be selected according to the specific scenario. The low gap between the substrate and the detector can achieve a high degree of integration.

[0078] In other examples, the optical system may further include a lens group comprising at least one lens, which, together with the superlens, shapes the incident light. Alternatively, the functional layer may be implemented as a lens group.

[0079] Based on the above design concept, for the optical system of a TOF lens, in one example, the designed FOV is 55°, the designed aperture size is 1.24mm, the distance from the aperture to the coated metalens is 1.21mm, the substrate thickness including the coating layer and the substrate itself is 1.5mm, the distance from the detector to the metasurface is less than 0.5mm, the operating wavelength is λ = 850nm, the desired focal length is F = 1.36mm, and the radius of the designed metalens is R = 1.35mm. The coefficients of the parameters are:

[0080] Table 1

[0081]

[0082] This yields a graph showing the relationship between the phase (theoretical / realized) and the radius of a superlens with a focal length of 1.36mm and an aperture of 1.35mm at 850nm, as detailed below. Figures 7 to 9 As shown. Among them, Figure 7 The illustration shows a target design schematic diagram of an optical system having a superlens structure of a lens according to an embodiment of this application. Figure 8A and Figure 8B The diagrams illustrate the optimized amplitude and phase of the superlens structure of the lens according to embodiments of this application for both tetragonal and hexagonal configurations. Figure 9 The illustration shows the results of an optimization analysis of the tetragonal variable-period superlens design of the superlens structure of the lens according to an embodiment of this application.

[0083] like Figure 9 As shown, the modulation transfer function of the optical system of the lens having the superlens structure of the lens according to the embodiment of this application reaches the diffraction limit in each field of view, demonstrating that the optical system has good imaging capability.

[0084] Alternatively, the optical system of a lens having a superlens structure according to an embodiment of this application can also be designed in a non-proximity optical system, for example, based on the above requirements, as shown in the following example. Figure 10 The results are shown here. Figure 10 The illustration shows a schematic diagram of another design result of an optical system having a superlens structure of a lens according to an embodiment of this application.

[0085] in, The design parameters yield the following results:

[0086]

[0087] Furthermore, the corresponding design MTF and relative illumination effects are as follows: Figure 11 and Figure 12 As shown. Figure 11 The diagram shows... Figure 10The diagram shows a schematic of the design MTF of an optical system for a lens having a superlens structure according to an embodiment of this application. Figure 12 The diagram shows... Figure 10 The diagram shows the relative illumination effect of an optical system having a superlens structure according to an embodiment of this application.

[0088] The basic principles of this application have been described above with reference to specific embodiments. However, it should be noted that the advantages, benefits, and effects mentioned in this application are merely examples and not limitations, and should not be considered as essential features of each embodiment of this application. Furthermore, the specific details disclosed above are for illustrative and facilitative purposes only, and are not limitations. These details do not limit the application to the necessity of employing the aforementioned specific details for implementation.

[0089] The block diagrams of devices, apparatuses, devices, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As those skilled in the art will recognize, these devices, apparatuses, devices, and systems can be connected, arranged, and configured in any manner. Words such as “comprising,” “including,” “having,” etc., are open-ended terms meaning “including but not limited to,” and are used interchangeably with them. The terms “or” and “and” as used herein refer to the terms “and / or,” and are used interchangeably with them unless the context clearly indicates otherwise. The term “such as” as used herein refers to the phrase “such as but not limited to,” and is used interchangeably with it.

[0090] It should also be noted that in the apparatus, equipment, and methods of this application, the components or steps can be disassembled and / or recombined. These disassemblies and / or recombinations should be considered as equivalent solutions of this application.

[0091] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use this application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein can be applied to other aspects without departing from the scope of this application. Therefore, this application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0092] The above description has been given for purposes of illustration and description. Furthermore, this description is not intended to limit the embodiments of this application to the forms disclosed herein. Although numerous exemplary aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A superlens structure of a lens, comprising: a light-transmitting substrate; and a nanostructure disposed on at least one side surface of the substrate, wherein the nanostructure comprises a plurality of nano-units based on a square or hexagonal unit, the plurality of nano-units based on a square or hexagonal unit forming one or more square or hexagonal ring-shaped nano-unit groups and gaps formed between the nano-unit groups.

2. The lens of the metasurface structure according to claim 1, wherein, The ring-shaped diameter of the plurality of square or hexagonal ring-shaped nano-unit groups and the square or hexagonal unit-based lattice of the nano-units in the nano-unit groups are not the same. 3.The superlens structure of a lens according to claim 1, wherein, The nano-units in the nano-unit groups are coaxially and square or hexagonally distributed. 4.The superlens structure of a lens according to claim 1, wherein, The widths of the at least part of the gaps are not equal, and / or the heights of the nano-units are equal. 5.The superlens structure of a lens according to claim 1, wherein, The nano-units belonging to different ring-shaped nano-unit groups have the same height and different lattice sizes.

6. The superlens structure of a lens according to claim 1, further comprising: one or more film layers disposed on the other side surface of the substrate opposite to the nanostructure. 7.The superlens structure of a lens according to claim 6, wherein, The materials of the nano-units, the substrate and the film layers are one of the following: photoresist, silicon nitride, titanium oxide, monocrystalline silicon, polycrystalline silicon, amorphous silicon, gallium nitride (GaN), hafnium oxide (HfO2), halide crystal, sapphire and other oxide crystal, quartz, chalcogenide crystal, glass, plastic or semiconductor material. 8.The superlens structure of a lens according to claim 1, wherein, The gaps are air or a material having a refractive index different from that of the material of the ring-shaped nano-unit groups. 9.The superlens structure of a lens according to claim 1, wherein, at least two nano-units in the nanostructure have a diameter s n , a period size P m , or a position r n are not equal, the period size P m is a unit edge length of a square or hexagonal unit corresponding to the nano-unit, and the position r n is a distance from a center of the nano-unit to a center of the superlens structure. 10.The superlens structure of a lens according to claim 1, wherein, In the case that the nanostructure transmits visible light, the height H of the nanostructure is greater than or equal to 100 nm and less than or equal to 1500 nm, the distance between adjacent nano-units is greater than or equal to 40 nm and less than or equal to 850 nm, and the minimum size of the nano-units is 30 nm. 11.The superlens structure of a lens according to claim 1, wherein, In the case that the nanostructure transmits infrared light in the wavelength band of 820 nm to 880 nm, the height H of the nanostructure is greater than or equal to 100 nm and less than or equal to 8 μm, the distance between adjacent nano-units is greater than or equal to 50 nm and less than or equal to 2 μm, and the minimum size of the nano-units is 50 nm.

12. An optical system of a lens, comprising in order from an object side: a functional layer; a diaphragm; and the superlens structure of a lens according to any one of claims 1 to 11.

13. The optical system of the lens according to claim 12, wherein, The functional layer comprises one or more of a glass cover plate, a polarizer, a 1 / 2 wave plate, a 1 / 4 wave plate, an anti-reflection film or an anti-reflective film.

14. The optical system of claim 12, wherein, The diaphragm is attached to the surface of the functional layer or is a light transmission aperture formed by coating on one side of the functional layer based on semiconductor technology.

15. The optical system of a lens according to claim 12, further comprising a detector, which is an imaging chip.

16. The optical system of the lens according to claim 12, wherein, The size of the diaphragm is 1.24 mm, the distance from the diaphragm to the side surface of the substrate of the superlens structure opposite to the nanostructure is 1.16 mm, the thickness of the substrate is 0.3 mm, and the distance from the detector to the surface of the nanostructure is greater than 1.5 mm and less than 2 mm.

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