A design method of a monolithic polarization multiplexing bifunctional superlens device and a superlens device

Abstract

The application discloses a design method of a single-chip polarization multiplexing bifunctional super lens device and the super lens device, and belongs to the technical field of optical imaging. The designed device can realize independent bright field and edge enhancement imaging functions according to the polarization state of incident light. The cross section of the nanometer unit of the device is anisotropic C2 symmetry shape, and the long and short axes of the cross section are perpendicular to each other, so that linearly polarized light with a polarization direction parallel and perpendicular to the long axis has independent phase delay after passing through the nanometer unit. Therefore, based on waveguide phase or waveguide plus geometric phase regulation, the bright field and edge enhancement imaging phases are respectively applied to a pair of orthogonal polarization states, so that the device can perform bright field imaging in one polarization state and edge enhancement imaging in the other polarization state. Without the aid of other imaging devices and under the condition of meeting the resolution requirement, the bifunctional imaging with a wide working bandwidth and high imaging mode switching convenience can be realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of optical imaging, and more particularly relates to a design method of a monolithic polarization multiplexing bifunctional superlens device and a superlens device. BACKGROUND

[0002] Optical imaging technology is one of the important tools for exploring and understanding the world, and is widely used in biomedical imaging, material characterization and environmental detection. Among the many optical imaging modes, bright-field imaging mode and edge-enhanced imaging mode are two of the most representative imaging modes. These two imaging modes complement each other and can obtain different morphological information of the target object. Therefore, developing an imaging system that can conveniently switch between these two imaging modes has important application value and prospect for a series of applications such as biomedical imaging and material detection. However, due to the working principle, it is difficult for traditional optical systems to organically combine these two imaging modes.

[0003] In recent years, optical superlenses composed of subwavelength superatoms have shown great potential in constructing compact and high-performance optical imaging systems. Superlenses can effectively reproduce a variety of functions of traditional bright-field imaging systems, such as diffraction-limited imaging, chromatic aberration correction, and large-field imaging, and significantly reduce the size of the entire imaging system. In addition, by carefully designing the unit structure and its arrangement, superlenses can also achieve novel bright-field imaging functions that traditional lenses cannot achieve, such as polarization imaging, chiral imaging, and three-dimensional imaging. On the other hand, superlenses have also been applied to develop high-performance edge-enhanced imaging systems. Edge-enhanced imaging systems based on superlenses have unique advantages such as compact size and high image processing precision.

[0004] Although the superlens shows great potential in high-performance optical imaging systems, due to the significant difference in design principles between the two imaging modes of bright-field and edge-enhanced imaging, most of the superlens-based imaging systems currently still work in a single imaging mode. In recent years, researchers have tried to develop dual-function imaging systems based on superlenses by mechanical stretching, phase-change materials or combining 4f system structure, etc. Among them, the mechanical stretching method is to switch the imaging function by changing the period of superlattice atoms. Before stretching, the working wavelength of the superlattice atoms is at the resonance point, which can effectively filter out the low-frequency components of the object to realize the edge-enhanced imaging function; after stretching, the working wavelength is far away from the resonance point, and the spectrum of the object is no longer modulated, realizing the bright-field imaging function. This imaging mode switching method needs to work near the resonance point of the superlens, thereby limiting the working bandwidth, and the imaging quality is also easily affected by the change of the resonance point and decreased. The phase-change material method is to switch the imaging mode by changing the properties of the material. The change of the properties of the material needs to introduce additional external light-thermal stimulation, in addition, the switching between the crystalline and amorphous states of the phase-change material needs a certain time, so this switching method has problems in switching convenience. In the 4f system, the switching of the imaging mode needs additional lens groups and physical space to form 4f, which greatly reduces the integration of the whole system.

[0005] The above methods still face challenges in system size, imaging resolution, working bandwidth and switching convenience, etc. In addition, these methods only have the function of switching the imaging mode, and do not have the imaging function, and need to rely on the 4f imaging system or other imaging modules to capture the final imaging result. SUMMARY

[0006] In view of the above defects or improvement needs of the prior art, the present application provides a design method of a single-chip polarization multiplexing dual-function superlens device and a superlens device, which aims to provide a dual-function superlens device with a wider working bandwidth and higher imaging mode switching convenience without the aid of other imaging devices and under the condition of meeting the imaging resolution requirement.

[0007] To achieve the above-mentioned purpose, in a first aspect, the present application provides a design method of a single-chip polarization multiplexing dual-function superlens device, comprising:

[0008] The nanometer array is arranged on the A surface of the substrate; the nanometer array comprises: each anisotropic nanometer unit arranged periodically, with the same height and subwavelength size; the cross section of the nanometer unit parallel to the A surface is in C2 symmetry shape, and the long axis and the short axis of the cross section are perpendicular to each other;

[0009] An x-y coordinate system is established on the A surface;

[0010] When the incident light is x-polarized light or y-polarized light, and the superlens device is used to perform bright-field imaging on the target object under x-polarized light and perform edge-enhanced imaging on the target object under y-polarized light, each nanometer unit is arranged such that the angle between the long axis of each nanometer unit and the x-axis on the A plane is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is satisfies:

[0011] wherein, is a phase distribution such that the intensity distribution of the point spread function of the superlens device is an Airy disk distribution, and the phase distribution of the point spread function is a constant phase distribution; is a phase distribution such that the intensity distribution of the point spread function of the superlens device is a donut distribution, and the phase distribution of the point spread function is a vortex phase distribution;

[0012] The target object and the superlens device are sequentially arranged in the propagation direction of the incident light, and the propagation direction of the incident light is perpendicular to the A plane.

[0013] Further preferably, in a polar coordinate system corresponding to the x-y coordinate system, the phase distribution the phase value at the position (r, θ) in the phase distribution and the phase value at the position (r, θ) in the phase distribution are respectively:

[0014]

[0015]

[0016] wherein λ0 is the target working wavelength of the superlens device; f is the target focal length of the superlens device; C is an arbitrary constant; and l is the topological charge number of the vortex phase.

[0017] Further preferably, when the incident light is x-polarized light or y-polarized light, and the superlens device is used to perform edge-enhanced imaging on the target object under x-polarized light and perform bright-field imaging on the target object under y-polarized light, each nanometer unit is arranged such that the angle between the long axis of each nanometer unit and the x-axis on the A plane is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is satisfies:

[0018] ​Further preferably, when the incident light is left-handed circularly polarized light or right-handed circularly polarized light, and the meta-lens device is used to perform bright field imaging of the target object under left-handed circularly polarized light and edge-enhanced imaging of the target object under right-handed circularly polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is satisfy:

[0019]

[0020]

[0021] Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, and the rotation angle distribution θ' of the nanometer array is formed. θ' satisfies:

[0022]

[0023] Further preferably, when the incident light is left-handed circularly polarized light or right-handed circularly polarized light, and the meta-lens device is used to perform edge-enhanced imaging of the target object under left-handed circularly polarized light and bright-field imaging of the target object under right-handed circularly polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is And θ' satisfies:

[0024]

[0025]

[0026] Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, and the rotation angle distribution θ' of the nanometer array is formed. θ' satisfies:

[0027]

[0028] Further preferably, when the incident light is left-handed elliptically polarized light or right-handed elliptically polarized light orthogonal to the left-handed elliptically polarized light, and the meta-lens device is used to perform bright field imaging of the target object under left-handed elliptically polarized light and edge-enhanced imaging of the target object under right-handed elliptically polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A plane is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is respectively Then, each nanometer unit is rotated counterclockwise on the A plane with the lattice center of the meta-unit as the rotation center, forming the rotation angle distribution θ' of the nanometer array; the phase distribution of the nanometer array in the x and y polarization directions is and θ' satisfies:

[0029]

[0030] wherein the polarization azimuth angle of the left-handed elliptically polarized light and the right-handed elliptically polarized light is ω, and the phase difference of the components of the left-handed elliptically polarized light and the right-handed elliptically polarized light in the x-axis and y-axis directions is * is a conjugate symbol.

[0031] Further preferably, when the incident light is left-handed elliptically polarized light or right-handed elliptically polarized light orthogonal to the left-handed elliptically polarized light, and the superlens device is used to perform edge-enhanced imaging on a target object under the left-handed elliptically polarized light and perform bright-field imaging on the target object under the right-handed elliptically polarized light, each nanometer unit is arranged such that the angle between the long axis of each nanometer unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is Further preferably, when the incident light is left-handed elliptically polarized light or right-handed elliptically polarized light orthogonal to the left-handed elliptically polarized light, and the superlens device is used to perform edge-enhanced imaging on a target object under the left-handed elliptically polarized light and perform bright-field imaging on the target object under the right-handed elliptically polarized light, each nanometer unit is arranged such that the angle between the long axis of each nanometer unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is and θ' satisfies:

[0032]

[0033] wherein the polarization azimuth angle of the left-handed elliptically polarized light and the right-handed elliptically polarized light is ω, and the phase difference of the components of the left-handed elliptically polarized light and the right-handed elliptically polarized light in the x-axis and y-axis directions is * is a conjugate symbol.

[0034] Further preferably, the shape of the nanometer unit is a rectangular prism, an elliptical prism, or a cross-shaped prism.

[0035] Further preferably, the material of the nanometer unit is a dielectric material with a refractive index greater than 1.5 and an absorption coefficient less than 0.5 in the working waveband of the device.

[0036] In a second aspect, the present application provides a monolithic polarization multiplexing dual-function superlens device, which is designed by using the design method of the polarization multiplexing dual-function superlens device provided in the first aspect of the present application, and comprises: a substrate and a nanometer array arranged on the A surface of the substrate, for performing bright-field imaging or edge-enhanced imaging on a target object under orthogonal polarized state incident light illumination.

[0037] Overall, the above technical solutions conceived by the present application can achieve the following beneficial effects:

[0038] 1. The application provides a design method of a single-chip polarization multiplexing bifunctional superlens device, the designed superlens device comprises periodically arranged, highly identical and subwavelength-sized anisotropic nanocells, wherein the cross section of the nanocell parallel to the A surface is in C2 symmetry shape, and the long axis and the short axis of the cross section are perpendicular to each other; through the design of the structure, the responses of the nanocell in the x and y polarization state directions are different from each other, that is, the light beams with polarization directions parallel to the x axis and the light beams perpendicular to the x axis have independent phase retardations after passing through the superlens device, therefore, under the incidence condition of linearly polarized light, based on waveguide phase regulation, the phase distribution of bright field imaging is applied in the corresponding x polarization direction, the phase distribution of edge enhancement imaging is applied in the corresponding y polarization direction, so that the superlens device can perform bright field imaging on a target object under x linearly polarized light and perform edge enhancement imaging on the target object under y linearly polarized light; through the design method, the superlens device can realize the switching of the two imaging modes of bright field imaging and edge enhancement imaging by only switching the polarization state of the incident light, thereby avoiding the problems of limited working bandwidth and reduced imaging resolution caused by the existing mechanical stretching mode, and without introducing external light-thermal stimulation as in the existing phase change material mode to switch, the switching is convenient, at the same time, without introducing additional imaging devices to capture the final imaging result, the working bandwidth is wide and the imaging mode switching convenience is high under the condition of not relying on other imaging devices and meeting the imaging resolution requirement.

[0039] 2. Further, the design method of the polarization multiplexing bifunctional superlens device provided by the application can also, under the incidence condition of linearly polarized light, based on waveguide phase regulation, by applying the phase distribution of bright field imaging in the corresponding x polarization direction, the phase distribution of edge enhancement imaging in the corresponding y polarization direction, so that the superlens device can perform edge enhancement imaging on a target object under x linearly polarized light and perform bright field imaging on the target object under y linearly polarized light, further expanding the implementation mode of the bifunctional superlens device.

[0040] 3. Further, the design method of the polarization multiplexing bifunctional superlens device provided by the application can also, under the incidence condition of circularly polarized light, rotate each nanocell respectively, so that the long axis of the nanocell forms a certain rotation angle with the x axis on the A surface, based on waveguide phase and geometric phase regulation, the applied in the x polarization direction and the And the rotation angle distribution θ', that is, the super-structured lens device can perform bright field imaging or edge enhancement imaging on the target object under different circularly polarized light, further expanding the implementation mode of the dual-function super-structured lens device.

[0041] 4. Further, the design method of the polarization multiplexing dual-function super-structured lens device provided by the application can also rotate each nanometer unit under the incidence condition of elliptically polarized light, so that the long axis of the nanometer unit forms a certain rotation angle with the x axis on the A plane, and based on waveguide phase and geometric phase control, the phase and the phase in the y polarization direction are determined. And the rotation angle distribution θ', that is, the super-structured lens device can perform bright field imaging or edge enhancement imaging on the target object under different circularly polarized light, further expanding the implementation mode of the dual-function super-structured lens device.

[0042] 5. Further, the design method of the polarization multiplexing dual-function super-structured lens device provided by the application, the bright field imaging phase designed by the application is a hyperbolic phase, which can effectively eliminate the spherical aberration in imaging to realize bright field imaging with higher resolution; and the edge enhancement imaging phase is the superposition of hyperbolic phase and vortex phase, which can realize edge detection imaging with better imaging quality and higher resolution. BRIEF DESCRIPTION OF DRAWINGS

[0043] Figure 1 is the phase distribution diagram of the bright field imaging and vortex phase contrast imaging of the super-structured device provided by the embodiment of the application;

[0044] Figure 2 is a schematic diagram of the bright field imaging of the target object by the super-structured lens device under x linearly polarized light and the edge enhancement imaging of the target object by the super-structured lens device under y linearly polarized light provided by the embodiment of the application;

[0045] Figure 3 is the nanometer unit of two shapes under the embodiment 1 of the application; wherein a is the nanometer unit under the rectangular square column shape; b is the nanometer unit under the elliptical column shape;

[0046] Figure 4 is a schematic diagram of the super-structured lens device under the embodiment 1 of the application;

[0047] Figure 5 is a schematic diagram of the bright field imaging of the target object by the super-structured lens device under left-handed circularly polarized light and the edge enhancement imaging of the target object by the super-structured lens device under right-handed circularly polarized light under the embodiment 3 of the application;

[0048] Figure 6 is a schematic diagram of the super-structured lens device under the embodiment 3 of the application;

[0049] Figure 7 Fig. 5 is a schematic diagram of the superlens device of embodiment 5 of the present application for bright-field imaging of a target object under left-handed elliptically polarized light and for edge-enhanced imaging of the target object under right-handed elliptically polarized light. DETAILED DESCRIPTION

[0050] In order to make the objectives, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and should not be used to limit the present application. In addition, the technical features involved in the various embodiments of the present application described below can be combined with each other as long as they do not conflict with each other.

[0051] In order to achieve the above-mentioned purpose, in a first aspect, the present application provides a design method of a monolithic polarization multiplexing dual-function superlens device. The designed superlens device can directly image a target object without the aid of additional imaging devices, and can conveniently switch between bright-field and edge-enhanced imaging modes by changing the polarization state of the illumination beam.

[0052] Specifically, the design method of the monolithic polarization multiplexing dual-function superlens device comprises:

[0053] 1) arranging a nano array on the A surface of a substrate; wherein the nano array comprises: anisotropic nano units arranged periodically, with the same height, and with a subwavelength size; the cross section of the nano unit parallel to the A surface is in C2 symmetry shape, and the long axis and the short axis of the cross section are perpendicular to each other; wherein the A surface is any surface of the substrate;

[0054] It should be noted that the nano unit is usually composed of a dielectric material with high refractive index (refractive index > 1.5) and low loss (absorption coefficient < 0.5) in the target working waveband of the device, which can be silicon, titanium dioxide, silicon nitride, gallium nitride, tantalum pentoxide, etc., which is not limited here.

[0055] It should be noted that the shape of the nano unit can be a rectangular square column, an elliptical column, a cross-shaped column (cross-shaped section), etc., which is not limited here. Preferably, in an optional embodiment, the shape of the nano unit is a rectangular square column or an elliptical column.

[0056] 2) obtaining the phase distribution of the nano array for bright-field and edge-enhanced imaging and using different polarization multiplexing methods to superimpose them on a pair of orthogonal polarization channels, thereby realizing convenient switching between the two imaging functions;

[0057] It should be noted that the way to obtain There are many ways to do this, as long as the following conditions are met: In order to make the intensity distribution of the point spread function of the superlens device an Airy disk distribution, the phase distribution of the point spread function is a constant phase distribution. In order to make the intensity distribution of the point spread function of the superlens device a donut distribution, the phase distribution of the point spread function is a vortex phase distribution.

[0058] In an optional embodiment, in order to realize the near-diffraction-limit bright-field imaging function, the phase distribution is the superposition of a hyperbolic phase and a constant phase; in order to realize the edge-enhanced imaging function, the phase distribution is the superposition of a hyperbolic phase and a vortex phase with a topological charge l = +1 or l = -1.

[0059] Specifically, in a polar coordinate system corresponding to the x-y coordinate system, the phase distribution at a position (r, θ) is and the phase distribution at a position (r, θ) is respectively.

[0060]

[0061]

[0062] wherein λ0 is a target working wavelength of the superlens device; f is a target focal length of the superlens device; C is an arbitrary constant; and l is a topological charge of the vortex phase.

[0063] As shown in FIG. 4, a phase distribution diagram of a bright-field imaging and vortex phase contrast imaging of the superlens device provided in the embodiment is shown, wherein the constant C is set to 0, and the topological charge l is +1. Figure 1

[0064] It should be noted that the above-mentioned manner of obtaining and is not unique, and the type of coordinate system is also not unique. For example, and may also be directly represented in the x-y coordinate system, and specifically are:

[0065]

[0066]

[0067] For another example, in another optional embodiment,

[0068]

[0069] ​

[0070] Herein, no limitation is made.

[0071] In an alternative embodiment, a superlens device with a diameter of 3 mm and a focal length of 1.75 mm at a target wavelength of 671 nm is designed, which is composed of anisotropic nanocolumn array with a period P of 320 nm and a height H of 500 nm, and is used to exert independent and arbitrary phase control on a pair of orthogonal polarization states. In order to maintain the working efficiency in the target working waveband, the superlens device is composed of dielectric materials with high refractive index and low loss in the target working waveband. Taking the design wavelength of 671 nm as an example, the preferred material is a dielectric material with high refractive index (refractive index > 1.5) and low loss (absorption coefficient < 0.5) in the working waveband, including silicon (Si), titanium dioxide (TiO2), silicon nitride (SiNx), gallium nitride (GaN), tantalum pentoxide (Ta2O5), etc.

[0072] It should be noted that it can be extended to other working wavebands by only changing the constituent materials of the device.

[0073] By adjusting the numerical aperture of the superlens, higher resolution bright-field and edge-enhanced imaging can be achieved.

[0074] The following provides a variety of embodiments for utilizing different polarization multiplexing methods to apply to a pair of orthogonal polarization channels to achieve convenient switching of two imaging functions, the specific process including:

[0075] First, an arbitrary x-y coordinate system is established on the A surface;

[0076] Then the corresponding operation is realized under different embodiments.

[0077] Embodiment 1

[0078] In this embodiment, the type of incident illumination beam is linearly polarized light, including orthogonal x linearly polarized light and y linearly polarized light, and the superlens device is required to perform bright-field imaging on the target object under x linearly polarized light and edge-enhanced imaging on the target object under y linearly polarized light.

[0079] In order to achieve the above requirements, the nanocells are arranged such that the angle between the long axis of each nanocell and the x axis on the A surface is 0° or 90°, and the phase distribution of the nanocolumn array in the x and y polarization directions satisfies: wherein the target object and the superlens device are sequentially arranged in the propagation direction of the linearly polarized light, and the propagation direction of the linearly polarized light is perpendicular to the A surface. It should be noted that the phase distribution of the nanocolumn array includes the phase of each nanocell at each position.

[0080] Specifically, as Figure 2 ​The schematic diagram of the superlens device for bright-field imaging of a target object under x-linear polarization and for edge-enhanced imaging of the target object under y-linear polarization is shown. In this embodiment, the superlens device comprises a fused silica substrate 1 and a nanoarray (transmission-type superlens device) 2. When x-linear polarization (XLP) is illuminated onto a target object 3, the superlens device can perform bright-field imaging of the object close to the diffraction limit, while when y-linear polarization (YLP) is illuminated onto the target object 3, the superlens device can effectively extract the edge profile of the object.

[0081] In this embodiment, as shown in Figure 3 The two shapes of the nano units are shown, in which the angle between the long axis of the nano unit and the x-axis on the A plane is 0° or 90°. In the figure, a represents a rectangular prism-shaped nano unit, and b represents an elliptical cylinder-shaped nano unit. 1 represents a nano unit, and 2 represents a fused silica substrate. In this embodiment, the rectangular prism or elliptical cylinder-shaped nano units made of a material (for example, silicon, titanium dioxide, silicon nitride, gallium nitride, tantalum pentoxide, etc.) transparent or having a low absorption in the target working waveband are provided, in which P represents a superatom period, D1 and D2 represent the dimensions of the long axis and the short axis, respectively, θ' is the angle between the long axis of the nano unit and the x-axis, and H is the height of the nano unit (which is usually uniform).

[0082] Figure 4 The schematic diagram of the superlens device provided in this embodiment is periodically arranged by anisotropic nano units with different geometric dimensions, fixed rotation angles, and the same height. This embodiment uses a waveguide phase control method and works under linear polarization incidence. The phase control is usually applied to transmitted light, and the amount of phase control applied can be represented as where k0 is the wave vector of the incident light in free space, n eff is the equivalent refractive index of the nano unit, which is determined by the shape, size, material, and period of the nano unit, and H is the height of the nano unit. Since the nano unit is anisotropic, the linearly polarized light beams parallel and perpendicular to the long axis have independent and arbitrary phase delays after passing through the nano unit, i.e.,

[0083] According to the phase distribution and The nano units with corresponding sizes are arranged to obtain the superlens device.

[0084] Embodiment 2

[0085] In this embodiment, the type of incident illumination light beam is a linearly polarized light beam, including orthogonal x-polarized light and y-polarized light. The meta-lens device is required to perform edge-enhanced imaging of the target object under x-polarized light and bright-field imaging of the target object under y-polarized light.

[0086] In order to achieve the above requirements, the nano units are arranged so that the angle between the long axis of each nano unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano array in the x and y polarization directions is satisfy: The target object and the meta-lens device are sequentially arranged in the propagation direction of the linear polarized light, and the propagation direction of the linear polarized light is perpendicular to the A surface.

[0087] The concept of the scheme is similar to that of Example 1, and the relevant technical scheme is the same as that of Example 1, which will not be described in detail here.

[0088] Example 3

[0089] In this embodiment, the type of the incident illumination light beam is an orthogonal circularly polarized light beam, including left-handed circularly polarized light and right-handed circularly polarized light. The meta-lens device is required to perform bright field imaging of the target object under left-handed circularly polarized light and to perform edge-enhanced imaging of the target object under right-handed circularly polarized light.

[0090] In order to achieve the above requirements, the nano units are arranged so that the angle between the long axis of each nano unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano array in the x and y polarization directions is satisfy:

[0091]

[0092]

[0093] Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, and the rotation angle distribution θ' of the nanometer array is formed. θ' satisfies:

[0094]

[0095] The target object and the meta-lens device are sequentially arranged in the propagation direction of the circularly polarized light, and the propagation direction of the circularly polarized light is perpendicular to the A-plane.

[0096] Specifically, if Figure 5Figure 1 shows a schematic diagram of a metalens device performing brightfield imaging of a target object under left-handed circularly polarized light and edge-enhanced imaging of the target object under right-handed circularly polarized light. In this embodiment, the metalens device comprises a fused silica substrate 1 and a nanoarray 2. When left-handed circular polarization (LCP) light illuminates a target object 3, the metalens device can perform brightfield imaging of the object close to the diffraction limit. When right-handed circular polarization (RCP) light illuminates the target object 3, the metalens device can effectively extract the edge contour of the object.

[0097] Figure 6 This is a schematic diagram of the metalens device provided in this embodiment. It is composed of a periodic arrangement of anisotropic nanounits of varying geometric dimensions, rotation angles, and uniform height. This implementation utilizes waveguide phase plus geometric phase control, operating under conditions of incident left-handed and right-handed circularly polarized light. When the incident beam is left-handed and right-handed circularly polarized, each nanounit corresponds to an anisotropic half-wave plate. The chirality of the incident and exiting beams is flipped, and the phase delay of linearly polarized beams with polarization directions parallel (XLP) and perpendicular (YLP) to the fast axis after passing through the nanoarray is: The rotation angle distribution of the nanounits in the nanoarray is:

[0098] According to the phase distribution and Nanounits of corresponding sizes are selected and rotated by corresponding angles to obtain a meta-lens device.

[0099] Example 4

[0100] In this embodiment, the types of incident illumination beams are orthogonal circularly polarized beams, i.e., left-handed circularly polarized light and right-handed circularly polarized light. The meta-lens device is required to perform edge-enhanced imaging of the target object under left-handed circularly polarized light and to perform bright-field imaging of the target object under right-handed circularly polarized light.

[0101] In order to achieve the above requirements, the nano units are arranged. First, the angle between the long axis of each nano unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano array in the x and y polarization directions is satisfy:

[0102]

[0103]

[0104] Then each nanometer unit is rotated counterclockwise on the A plane with the lattice center as the rotation center to form a rotation angle distribution θ' of the nanometer array, and θ' satisfies:

[0105]

[0106] The target object and the superlens device are sequentially arranged in the propagation direction of the circularly polarized light, and the propagation direction of the circularly polarized light is perpendicular to the A plane.

[0107] The scheme concept is similar to that of embodiment 3, and the related technical solutions are the same as those of embodiment 3, which will not be repeated here.

[0108] Embodiment 5

[0109] In this embodiment, the type of the incident illumination beam is an elliptical polarized beam, which includes orthogonal left-handed elliptical polarized light and right-handed elliptical polarized light, and the superlens device is required to perform bright field imaging on the target object under the left-handed elliptical polarized light and perform edge-enhanced imaging on the target object under the right-handed elliptical polarized light .

[0110] In order to achieve the above requirements, the nanometer units are arranged such that the angle between the long axis of each nanometer unit and the x axis on the A plane is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is Each nanometer unit is rotated counterclockwise on the A plane with the lattice center as the rotation center to form a rotation angle distribution θ' of the nanometer array. The phase distribution of the nanometer array in the x and y polarization directions and θ' satisfy:

[0111]

[0112] The polarization azimuth angle of the left-handed elliptical polarized light and the right-handed elliptical polarized light is ω, and the phase difference between the components of the left-handed elliptical polarized light and the right-handed elliptical polarized light in the x and y axis directions is * is a conjugate symbol.

[0113] The target object and the superlens device are sequentially arranged in the propagation direction of the elliptical polarized light, and the propagation direction of the elliptical polarized light is perpendicular to the A plane.

[0114] Specifically, as Figure 7The figure shows the schematic diagram of the superlens device in left-handed elliptical polarization (LEP) light for bright-field imaging of the target object and in right-handed elliptical polarization (REP) light for edge-enhanced imaging of the target object. In this embodiment, the superlens device comprises a fused quartz substrate 1 and a nano-array 2. When the left-handed elliptical polarization (LEP) light is illuminated on the target object 3, the superlens device can perform the bright-field imaging of the object close to the diffraction limit, while the right-handed elliptical polarization (REP) light is illuminated on the target object 3, the superlens device can effectively extract the edge profile of the object.

[0115] This embodiment utilizes the geometric phase plus waveguide phase control method and works under the condition of elliptical polarization light incidence. When the incident light beam is elliptical polarization light, each nano unit corresponds to an anisotropic wave plate, and a pair of orthogonal left-handed and right-handed elliptical polarization light changes its chirality after passing through the nano unit and adds phase delay and Specifically,

[0116]

[0117]

[0118] wherein the incident light beam α and the emergent light beam α * have opposite polarization chirality; |α + > and |α - > are a pair of orthogonal left-handed and right-handed elliptical polarization light, which can be expressed as:

[0119]

[0120] Thus, the Jones matrix of the nano unit is:

[0121]

[0122] The Jones matrix of the nano unit is diagonalized, and the phase response and the rotation angle of the nano unit are obtained:

[0123]

[0124] According to the phase distribution and The nano unit of the corresponding size is adopted, and the nano unit is rotated by the corresponding angle, so as to obtain the superlens device.

[0125] Embodiment 6

[0126] In this embodiment, the type of the incident illumination beam is an elliptical polarized beam, including orthogonal left-handed elliptical polarized light and right-handed elliptical polarized light, and the superlens device is required to have a phase distribution in the x and y polarization directions of The target object is subjected to edge-enhanced imaging under the left-handed elliptical polarized light When the target object is subjected to bright-field imaging under the right-handed elliptical polarized light

[0127] The nanometer units are arranged such that the angle between the long axis of each nanometer unit and the x axis on the A plane is 0° or 90°, and the phase distribution of the nanometer array in the x and y polarization directions is Each nanometer unit is subjected to counterclockwise rotation on the A plane with the lattice center thereof as the rotation center to form a rotation angle distribution θ' of the nanometer array. The phase distribution of the nanometer array in the x and y polarization directions is and θ' satisfy:

[0128]

[0129] wherein the polar azimuth angle of the left-handed elliptical polarized light and the right-handed elliptical polarized light is ω, and the phase difference between the components of the left-handed elliptical polarized light and the right-handed elliptical polarized light in the x and y axis directions is * is a conjugate symbol.

[0130] The target object and the superlens device are sequentially arranged in the propagation direction of the elliptical polarized light, and the propagation direction of the elliptical polarized light is perpendicular to the A plane.

[0131] The scheme concept is similar to that of Embodiment 5, and the related technical solutions are the same as those of Embodiment 5, which will not be described herein.

[0132] In a second aspect, the present application provides a monolithic polarization multiplexing bifunctional superlens device, which is designed by using the design method of the polarization multiplexing bifunctional superlens device provided in the first aspect of the present application, and includes a substrate and a nanometer array arranged on the A plane of the substrate, and is used for bright-field imaging or edge-enhanced imaging of a target object under orthogonal polarized state incident light illumination.

[0133] The related technical solutions are the same as the design method of the polarization multiplexing bifunctional superlens device provided in the first aspect of the present application, which will not be described herein.

[0134] Those skilled in the art can easily understand that the above description is only a preferred embodiment of the present application and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A design method for a monolithic polarization multiplexing dual-function meta-lens device, characterized in that: include: A nanoarray is disposed on surface A of a substrate; the nanoarray comprises: anisotropic nanounits arranged in a periodic pattern, having the same height and sub-wavelength size; a cross section of the nanounit parallel to surface A has a C2 symmetric shape, and the major axis and minor axis of the cross section are perpendicular to each other; surface A is any surface of the substrate; Establish an xy coordinate system on surface A; When the incident light is x-polarized light or y-polarized light, and the meta-lens device is used to perform bright field imaging of the target object under x-polarized light and edge-enhanced imaging of the target object under y-polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is 、 satisfy: , ; in, To make the intensity distribution of the point spread function of the meta-lens device an Airy disk distribution and the phase distribution of the point spread function a constant phase distribution; In order to make the intensity distribution of the point spread function of the meta-lens device a donut distribution and the phase distribution of the point spread function a vortex phase distribution; The target object and the meta-lens device are sequentially arranged in a propagation direction of the incident light, and the propagation direction of the incident light is perpendicular to the A surface.

2. The design method of the polarization multiplexing dual-function meta-lens device according to claim 1, characterized in that: When the incident light is x-polarized light or y-polarized light, and the meta-lens device is used to perform edge-enhanced imaging of the target object under x-polarized light and bright-field imaging of the target object under y-polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is 、 satisfy: , .

3. The design method of the polarization multiplexing dual-function meta-lens device according to claim 1, characterized in that: When the incident light is left-handed circularly polarized light or right-handed circularly polarized light, and the meta-lens device is used to perform bright-field imaging of the target object under left-handed circularly polarized light and edge-enhanced imaging of the target object under right-handed circularly polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A plane is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions satisfies: Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center to form the rotation angle distribution of the nanometer array. , satisfy: 。 4. The design method of the polarization multiplexing dual-function meta-lens device according to claim 1, characterized in that: When the incident light is left-handed circularly polarized light or right-handed circularly polarized light, and the meta-lens device is used to perform edge-enhanced imaging of the target object under left-handed circularly polarized light and bright-field imaging of the target object under right-handed circularly polarized light: each nano-unit is arranged so that the angle between the long axis of each nano-unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is 、 satisfy: Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center to form the rotation angle distribution of the nanometer array. , satisfy: 。 5. The design method of the polarization multiplexing dual-function meta-lens device according to claim 1, characterized in that: When the incident light is left-handed elliptically polarized light or right-handed elliptically polarized light orthogonal to the left-handed elliptically polarized light, and the meta-lens device is used to perform bright field imaging of the target object under left-handed elliptically polarized light and edge-enhanced imaging of the target object under right-handed elliptically polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is respectively 、 , each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, forming the rotation angle distribution of the nanometer array ; Phase distribution of the nanoarray in the x and y polarization directions 、 , and the rotation angle distribution satisfy: Among them, the polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are The phase differences of the components of left-handed elliptically polarized light and right-handed elliptically polarized light in the x-axis and y-axis directions are ; * is the conjugation symbol.

6. The design method of the polarization multiplexing dual-function meta-lens device according to claim 1, characterized in that: When the incident light is left-handed elliptically polarized light or right-handed elliptically polarized light orthogonal to the left-handed elliptically polarized light, and the meta-lens device is used to perform edge-enhanced imaging of the target object under left-handed elliptically polarized light and bright-field imaging of the target object under right-handed elliptically polarized light: the nano-units are arranged so that the angle between the long axis of each nano-unit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nano-array in the x and y polarization directions is respectively 、 , each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, forming the rotation angle distribution of the nanometer array ; Phase distribution of the nanoarray in the x and y polarization directions 、 , and the rotation angle distribution satisfy: Among them, the polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are The phase differences of the components of left-handed elliptically polarized light and right-handed elliptically polarized light in the x-axis and y-axis directions are ; * is the conjugation symbol.

7. The method for designing a polarization multiplexing dual-function meta-lens device according to any one of claims 1 to 6, wherein: In the polar coordinate system corresponding to the xy coordinate system, the phase distribution Middle position Phase value at and phase distribution Middle position Phase value at They are: in, is the target operating wavelength of the meta-lens device; is the target focal length of the meta-lens device; C is an arbitrary constant; is the topological charge of the vortex phase.

8. The method for designing a polarization multiplexing dual-function meta-lens device according to any one of claims 1 to 6, wherein: The shape of the nanometer unit is a rectangular column, an elliptical column or a cross column.

9. The method for designing a polarization multiplexing dual-function meta-lens device according to any one of claims 1 to 6, wherein: The material of the nanometer unit is a dielectric material with a refractive index greater than 1.5 and an absorption coefficient less than 0.5 in the device working band.

10. A monolithic polarization multiplexing dual-function meta-lens device, characterized in that: The device is designed using the design method of the polarization multiplexing dual-function meta-lens device described in any one of claims 1 to 9, comprising: a substrate and a nano-array arranged on surface A of the substrate, for performing bright field imaging or edge-enhanced imaging of a target object under illumination with orthogonal polarization incident light.

Images