Design method of monolithic polarization multiplexing dual-function super-structure lens device and super-structure lens device

Abstract

The invention discloses a design method of a monolithic polarization multiplexing dual-function super-structure lens device and the super-structure lens device, and belongs to the technical field of optical imaging. The designed device can respectively realize independent bright field and edge enhancement imaging functions according to the polarization state of incident light; the cross section of the nano unit forming the device is in an anisotropic C2 symmetrical shape, and the long axis and the short axis of the cross section are perpendicular to each other, so that linearly polarized light parallel to and perpendicular to the long axis in the polarization direction has independent phase delay after passing through the nano unit. A bright field and an edge enhancement imaging phase are respectively applied to a pair of orthogonal polarization states, so that the device can carry out bright field imaging in one polarization state and carry out edge enhancement imaging in the other polarization state, and the imaging efficiency can be improved under the conditions that other imaging devices are not needed and the resolution requirement is met. And dual-function imaging with relatively wide working bandwidth and relatively high imaging mode switching convenience is realized.

Description

Technical Field

[0001] The present invention belongs to the field of optical imaging technology, and more specifically, relates to a design method of a monolithic polarization multiplexing dual-function meta-lens device and a meta-lens device. Background Art

[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, environmental testing and other fields. Among the many optical imaging modes, bright field imaging mode and edge enhancement imaging mode are the two 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 easily switch between these two imaging modes has important application value and prospects for a series of applications such as biomedical imaging and material testing. However, due to the limitations of its working principle, traditional optical systems are difficult to organically combine these two imaging modes.

[0003] In recent years, optical metalenses composed of subwavelength metaatoms have shown great potential in building compact, high-performance optical imaging systems. Metalenses can effectively reproduce the various functions of traditional brightfield imaging systems, such as diffraction-limited imaging, chromatic aberration correction, and large-field-of-view imaging, and significantly reduce the size of the entire imaging system. In addition, by carefully designing the unit structure and its arrangement, metalenses can also achieve novel brightfield imaging functions that are difficult to achieve with traditional lenses, such as polarization imaging, chiral imaging, and three-dimensional imaging. On the other hand, metasurfaces have also been used to develop high-performance edge-enhanced imaging systems. Edge-enhanced imaging systems based on metasurfaces have unique advantages such as compact size and high image processing accuracy.

[0004] Although metalenses have shown great potential in high-performance optical imaging systems, most of the current imaging systems based on metasurfaces still only work in a single imaging mode due to the significant differences in the design principles of metasurface devices for bright field and edge enhanced imaging. In recent years, researchers have tried to develop dual-function imaging systems based on metasurfaces by mechanical stretching, phase change materials, or combining 4f system structures. Among them, the mechanical stretching method is to switch the imaging function by changing the period of the metaatom. Before stretching, the working wavelength of the metaatom is at the resonance point, which can effectively filter out the low-frequency components of the object to achieve 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 metasurface, which limits the working bandwidth, and the imaging quality is also easily affected by the change of the resonance point and degraded. The method of using phase change materials is to switch the imaging mode by changing the properties of the material. The change of the material properties requires the introduction of additional external light and heat stimulation. In addition, it takes a certain amount of time for the phase change material to switch between the crystalline and amorphous states, so this switching method has problems in terms of switching convenience. Switching the imaging mode in a 4f system requires additional lens groups and physical space to form 4f, which greatly reduces the integration of the entire system.

[0005] The above methods still face challenges in terms of system size, imaging resolution, working bandwidth, and switching convenience. In addition, these methods only have the imaging mode switching function, but not the imaging function, and need to use a 4f imaging system or other imaging modules to capture the final imaging results. Summary of the invention

[0006] In view of the above defects or improvement needs of the prior art, the present invention provides a design method for a monolithic polarization multiplexing dual-function meta-lens device and a meta-lens device, the purpose of which is to provide a dual-function meta-lens device with a wide working bandwidth and high convenience in switching imaging modes without the need for other imaging devices and under the condition of meeting the imaging resolution requirements.

[0007] In order to achieve the above objectives, in a first aspect, the present invention provides a design method for a monolithic polarization multiplexing dual-function meta-lens device, comprising:

[0008] The nanoarray is arranged on the A surface of the substrate; the nanoarray includes: anisotropic nanounits that are periodically arranged, have the same height, and have a sub-wavelength size; the cross section of the nanounit parallel to the A surface is C2 symmetrical, and the major axis and the minor axis of the cross section are perpendicular to each other;

[0009] Establish an xy coordinate system on surface A;

[0010] 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 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:

[0011] 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; 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;

[0012] The target object and the meta-lens 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 surface.

[0013] Further preferably, in the polar coordinate system corresponding to the xy coordinate system, the phase distribution Phase value at position (r,θ) and phase distribution Phase value at position (r,θ) They are:

[0014]

[0015]

[0016] Wherein, λ0 is the target operating wavelength of the metalens device; f is the target focal length of the metalens device; C is an arbitrary constant; and l is the topological charge of the vortex phase.

[0017] Further preferably, 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 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:

[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, forming a rotation angle distribution θ' of the nanometer array, 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 perform 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, forming a rotation angle distribution θ' of the nanometer array, 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 nanounit is rotated counterclockwise on the A plane with the lattice center of the superunit as the rotation center, forming the rotation angle distribution θ' of the nanoarray; the phase distribution of the nanoarray in the x and y polarization directions And θ' satisfies:

[0029]

[0030] The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * is the conjugation 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 meta-lens device is used to perform edge-enhanced imaging of the target object under left-handed elliptically polarized light and perform 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 plane 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 plane with its lattice center 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 And θ' satisfies:

[0032]

[0033] The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * is the conjugation symbol.

[0034] Further preferably, the shape of the nano unit is a rectangular column, an elliptical column or a cross column.

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

[0036] In the second aspect, the present invention provides a monolithic polarization multiplexing dual-function meta-lens device, which is designed using the design method of the polarization multiplexing dual-function meta-lens device provided in the first aspect of the present invention, and includes: a substrate and a nano-array arranged on the A surface of the substrate, which is used for bright field imaging or edge-enhanced imaging of a target object under illumination of orthogonal polarization incident light.

[0037] In general, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0038] 1. The present invention provides a design method for a monolithic polarization multiplexing dual-function meta-lens device, wherein the designed meta-lens device comprises anisotropic nano-units that are periodically arranged, have the same height, and are sub-wavelength in size, wherein the cross section of the nano-unit parallel to the A plane is C2 symmetrical, and the major axis and the minor axis of the cross section are perpendicular to each other; through the design of the structure, the responses of the nano-unit in the x and y polarization state directions are different from each other, that is, the light beam with a polarization direction parallel to the x-axis and the light beam perpendicular to the x-axis have independent phase delays after passing through the meta-lens device, so under the condition of incident linear polarized light, based on waveguide phase control, the phase distribution of bright field imaging is adjusted. Applied in the corresponding x-polarization direction, the phase distribution of the edge enhancement imaging By applying it in the corresponding y-polarization direction, the meta-lens device can perform bright field imaging of the target object under x-polarized light, and perform edge-enhanced imaging of the target object under y-polarized light. The meta-lens device designed by this design method can realize the switching between the two imaging modes of bright field imaging and edge-enhanced imaging only by switching the polarization state of the incident light, avoiding the problems of limited working bandwidth and reduced imaging resolution caused by the existing mechanical stretching method, and there is no need to introduce additional external light and heat stimulation for switching like the existing phase change material method. The switching is convenient. At the same time, there is no need to introduce additional imaging devices to capture the final imaging results. It can achieve imaging with a wide working bandwidth and high convenience in imaging mode switching without the help of other imaging devices and meeting the imaging resolution requirements.

[0039] 2. Furthermore, the design method of the polarization multiplexing dual-function meta-lens device provided by the present invention can also be used to control the phase distribution of edge-enhanced imaging under the condition of incident linear polarized light. Applied in the corresponding x-polarization direction, the phase distribution of bright field imaging When applied in the corresponding y-polarization direction, the meta-lens device can perform edge-enhanced imaging of the target object under x-polarized light and bright-field imaging of the target object under y-polarized light, further expanding the implementation method of the dual-function meta-lens device.

[0040] 3. Furthermore, the design method of the polarization multiplexing dual-function meta-lens device provided by the present invention can also rotate each nano-unit separately under the incident condition of circularly polarized light, so that the long axis of the nano-unit and the x-axis form a certain rotation angle on the A plane, and determine the applied angle in the x-polarization direction based on the waveguide phase plus geometric phase control. and in the y polarization direction And the rotation angle distribution θ', the meta-lens device can perform bright field imaging or edge-enhanced imaging of the target object under different circularly polarized light, further expanding the implementation method of the dual-function meta-lens device.

[0041] 4. Furthermore, the design method of the polarization multiplexing dual-function meta-lens device provided by the present invention can also rotate each nano-unit separately under the incident condition of elliptically polarized light, so that the long axis of the nano-unit and the x-axis form a certain rotation angle on the A plane, and determine the applied angle in the x-polarization direction based on the waveguide phase plus geometric phase control. and in the y polarization direction And the rotation angle distribution θ', the meta-lens device can perform bright field imaging or edge-enhanced imaging of the target object under different elliptically polarized lights, further expanding the implementation methods of dual-function meta-lens devices.

[0042] 5. Furthermore, the design method of the polarization multiplexing dual-function meta-lens device provided by the present invention is to design a bright field imaging phase It is a hyperbolic phase, which can effectively eliminate the spherical aberration in imaging and achieve bright field imaging with higher resolution; edge enhancement imaging phase It is the superposition of the hyperbolic phase and the vortex phase, which can achieve edge detection imaging with better imaging quality and higher resolution. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 Phase distribution diagram of bright field imaging and vortex phase contrast imaging of the metadevice provided in an embodiment of the present invention;

[0044] Figure 2 A schematic diagram of a meta-lens device provided in an embodiment of the present invention performing bright field imaging of a target object under x-polarized light and performing edge-enhanced imaging of the target object under y-polarized light;

[0045] Figure 3 These are two shapes of nanounits in Example 1 of the present invention; wherein a is a nanounit in a rectangular square column shape; and b is a nanounit in an elliptical column shape;

[0046] Figure 4 Schematic diagram of a meta-lens device according to Embodiment 1 of the present invention;

[0047] Figure 5 Schematic diagram of the meta-lens device according to Example 3 of the present invention performing bright field imaging of a target object under left-handed circularly polarized light and performing edge-enhanced imaging of the target object under right-handed circularly polarized light;

[0048] Figure 6 Schematic diagram of a meta-lens device according to Embodiment 3 of the present invention;

[0049] Figure 7 This is a schematic diagram of the meta-lens device according to Example 5 of the present invention performing bright field imaging of a target object under left-handed elliptically polarized light and performing edge enhanced imaging of the target object under right-handed elliptically polarized light. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention 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 objectives, in the first aspect, the present invention provides a design method for a monolithic polarization-multiplexed dual-function meta-lens device. The designed meta-lens device can directly image the target object without the aid of an additional imaging device, and can conveniently switch between bright field and edge enhancement imaging modes by changing the polarization state of the illumination beam.

[0052] Specifically, the design method of the above-mentioned monolithic polarization multiplexing dual-function meta-lens device includes:

[0053] 1) Arranging a nanoarray on the A surface of a substrate; wherein the nanoarray comprises: anisotropic nanounits that are periodically arranged, have the same height, and are sub-wavelength in size; the cross section of the nanounit parallel to the A surface is C2 symmetrical, and the major axis and the minor 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 nanounit is usually composed of a dielectric material with a high refractive index (refractive index > 1.5) and low loss (absorption coefficient < 0.5) within the target operating band of the device, and can be silicon, titanium dioxide, silicon nitride, gallium nitride, tantalum pentoxide, etc., without limitation here.

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

[0056] 2) Obtaining the phase distribution of nanoarrays for bright field and edge-enhanced imaging Different polarization multiplexing methods are used to superimpose them on a pair of orthogonal polarization channels, thereby achieving convenient switching between the two imaging functions;

[0057] It should be noted that obtaining There are many ways to do this, you just need to meet the following requirements: 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.

[0058] In an optional embodiment, in order to achieve near diffraction-limited bright field imaging, the phase distribution It is the superposition of hyperbolic phase and constant phase. In order to realize edge enhancement imaging function, the phase distribution It is the superposition of the hyperbolic phase and the vortex phase with the topological kernel l=+1 or l=-1.

[0059] Specifically, in the polar coordinate system corresponding to the xy coordinate system, the phase distribution Phase value at position (r,θ) and phase distribution Phase value at position (r,θ) They are:

[0060]

[0061]

[0062] Wherein, λ0 is the target operating wavelength of the metalens device; f is the target focal length of the metalens device; C is an arbitrary constant; and l is the topological charge of the vortex phase.

[0063] like Figure 1 Shown is a phase distribution diagram of bright field imaging and vortex phase contrast imaging of the meta-device provided in this embodiment, where the constant C is set to 0 and the topological charge l is +1.

[0064] It should be noted that the above acquisition and The way to do it is not unique, and the type of coordinate system is not unique. For example, and It can also be directly expressed in the xy coordinate system, specifically:

[0065]

[0066]

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

[0068]

[0069]

[0070] There is no limitation here.

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

[0072] It should be noted that the device can be extended to other operating bands by simply changing the constituent materials of the device.

[0073] Higher-resolution bright-field and edge-enhanced imaging can be achieved by adjusting the numerical aperture of the meta-lens.

[0074] The following provides a variety of different polarization multiplexing methods. An embodiment of applying to a pair of orthogonal polarization channels to realize convenient switching of two imaging functions includes:

[0075] First, establish an arbitrary xy coordinate system on surface A;

[0076] Then, corresponding operations are implemented under different embodiments.

[0077] Example 1

[0078] In this embodiment, the type of the 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 bright field imaging of the target object under x-polarized light and edge enhanced imaging of the target object under y-polarized light.

[0079] 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 plane A. It should be noted that the phase distribution of the nanoarray includes the phase of the nanounit at each position.

[0080] Specifically, Figure 2As shown, a schematic diagram of a meta-lens device performing bright field imaging of a target object under x-polarized light and performing edge-enhanced imaging of a target object under y-polarized light. In this embodiment, the meta-lens device comprises a fused quartz substrate 1 and a nano-array (transmission-type meta-lens device) 2. When x-linear polarization (X-Linear Polarization, XLP) illuminates the target object 3, the meta-lens device can perform bright field imaging of the object close to the diffraction limit, and when y-linear polarization (Y-Linear Polarization, YLP) illuminates the target object 3, the meta-lens device can effectively extract the edge contour of the object.

[0081] In this embodiment, Figure 3 The figure shows two shapes of nanounits whose long axis and x-axis on the A surface have an angle of 0° or 90°, where a is a nanounit in a rectangular square column shape, and b is a nanounit in an elliptical column shape; 1 represents a nanounit, and 2 represents a fused quartz substrate. In this embodiment, nanounits in the shape of rectangular square columns or elliptical columns made of materials that are transparent or have a low absorptivity in the target working band (for example, silicon, titanium dioxide, silicon nitride, gallium nitride, tantalum pentoxide, etc.) are provided, where P represents the superstructure atomic period, D1 and D2 represent the size of the long axis and the short axis respectively, θ' is the angle between the long axis of the nanounit and the x-axis, and H is the height of the nanounit (usually the height is consistent).

[0082] Figure 4 The schematic diagram of the meta-lens device provided in this embodiment is composed of periodic arrangement of anisotropic nano-units of different geometric sizes, fixed rotation angles and the same height. This implementation method uses the waveguide phase control method and works under the condition of linear polarized light incidence. Phase control is usually applied to the transmitted light, and the applied phase control amount can be expressed as Where k0 is the wave vector of the incident light in free space, n eff is the equivalent refractive index of the nanounit, which is determined by the shape, size, material and period of the nanounit, and H is the height of the nanounit. Since the nanounit has anisotropy, the linearly polarized light beams with polarization directions parallel and perpendicular to the long axis have independent and arbitrary phase delays after passing through the nanounit, that is:

[0083] According to the phase distribution and Nano units of corresponding sizes are arranged to obtain a meta-lens device.

[0084] Example 2

[0085] In this embodiment, the type of the 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 perform 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: Among them, the target object and the meta-lens device are arranged in sequence 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 related 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, forming a rotation angle distribution θ' of the nanometer array, θ' satisfies:

[0094]

[0095] Among them, the target object and the meta-lens device are arranged in sequence in the propagation direction of the circularly polarized light, and the propagation direction of the circularly polarized light is perpendicular to the A surface.

[0096] Specifically, Figure 5The figure shows a schematic diagram of a meta-lens device performing bright field imaging of a target object under left-handed circularly polarized light and performing edge-enhanced imaging of a target object under right-handed circularly polarized light. In this embodiment, the meta-lens device comprises a fused quartz substrate 1 and a nano-array 2. When left-handed circular polarization (LCP) is illuminated onto a target object 3, the meta-lens device can perform bright field imaging of the object close to the diffraction limit, and when right-handed circular polarization (RCP) is illuminated onto the target object 3, the meta-lens device can effectively extract the edge contour of the object.

[0097] Figure 6 The schematic diagram of the meta-lens device provided in this embodiment is composed of anisotropic nano-units of different geometric sizes, rotation angles and heights arranged periodically. This implementation method uses the waveguide phase plus geometric phase control method and works under the condition of left-handed circularly polarized light incidence. When the incident light beam is left-handed circularly polarized light, each nano-unit corresponds to an anisotropic half-wave plate, and the chirality of the incident light beam and the outgoing light beam is flipped. The phase delay of the linearly polarized light beam with polarization directions parallel (XLP) and perpendicular (YLP) to the fast axis after passing through the nano-array is: The rotation angle distribution of nanounits in the nanoarray is:

[0098] According to the phase distribution and A nanounit of corresponding size is selected and the nanounit is rotated by a corresponding angle to obtain a meta-lens device.

[0099] Example 4

[0100] In this embodiment, the types of incident illumination light beams are orthogonal circularly polarized light 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 surface with its lattice center as the rotation center, forming the rotation angle distribution θ' of the nanometer array, θ' satisfies:

[0105]

[0106] Among them, the target object and the meta-lens device are arranged in sequence in the propagation direction of the circularly polarized light, and the propagation direction of the circularly polarized light is perpendicular to the A surface.

[0107] The concept of the scheme is similar to that of Example 3, and the relevant technical scheme is the same as that of Example 3, which will not be repeated here.

[0108] Example 5

[0109] In this embodiment, the incident illumination beam is an elliptically polarized beam, including orthogonal left-handed elliptically polarized light and right-handed elliptically polarized light. Bright field imaging of the target object is performed under right-handed elliptically polarized light. The target object is imaged by edge enhancement.

[0110] In order to achieve the above requirements, the nanounits are arranged so that the angle between the long axis of each nanounit and the x-axis on the A surface is 0° or 90°, and the phase distribution of the nanoarray in the x and y polarization directions is Each nanometer unit is rotated counterclockwise on the A plane with its lattice center as the rotation center, forming the rotation angle distribution θ' of the nanometer array. Phase distribution of the nanometer array in the x and y polarization directions And θ' satisfies:

[0111]

[0112] The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * is the conjugation symbol.

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

[0114] Specifically, Figure 7The figure shows a schematic diagram of a meta-lens device performing bright field imaging of a target object under left-handed elliptically polarized light and edge-enhanced imaging of a target object under right-handed elliptically polarized light. In this embodiment, the meta-lens device comprises a fused quartz substrate 1 and a nano-array 2. When left-handed elliptically polarized light (LEP) is illuminated onto a target object 3, the meta-lens device can perform bright field imaging of the object close to the diffraction limit, and when right-handed elliptically polarized light (REP) is illuminated onto the target object 3, the meta-lens device can effectively extract the edge contour of the object.

[0115] This embodiment uses the geometric phase plus waveguide phase control method and works under the condition of elliptically polarized light incident. When the incident light beam is elliptically polarized light, each nanounit corresponds to an anisotropic wave plate. After a pair of orthogonal left-right elliptically polarized lights pass through the nanounit, the chirality is flipped and a phase delay is added. and Specifically:

[0116]

[0117]

[0118] Among them, the incident beam α and the outgoing beam α * With opposite polarization chirality; |α + >with|α - >is a pair of orthogonal left-right elliptically polarized light, which can be expressed in rectangular coordinates as:

[0119]

[0120] The Jones matrix of the nanometer unit can be obtained as follows:

[0121]

[0122] By diagonalizing the Jones matrix of the nanounit, the phase response and rotation angle of the nanounit can be obtained:

[0123]

[0124] According to the phase distribution and Nano units of corresponding sizes are used and the nano units are rotated by corresponding angles to obtain a meta-lens device.

[0125] Example 6

[0126] In this embodiment, the incident illumination beam is an elliptically polarized beam, including orthogonal left-handed elliptically polarized light and right-handed elliptically polarized light. Edge-enhanced imaging of the target object is performed under right-handed elliptically polarized light. When performing bright field imaging of a target object:

[0127] The nanounits are arranged so that the angle between the long axis of each nanounit and the x-axis on the A plane is 0° or 90°, and the phase distribution of the nanoarray in the x and y polarization directions is Each nanometer unit is rotated counterclockwise on the A plane with its lattice center as the rotation center, forming the rotation angle distribution θ' of the nanometer array. Phase distribution of the nanometer array in the x and y polarization directions And θ' satisfies:

[0128]

[0129] The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * is the conjugation symbol.

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

[0131] The concept of the scheme is similar to that of Example 5, and the relevant technical scheme is the same as that of Example 5, which will not be repeated here.

[0132] In the second aspect, the present invention provides a monolithic polarization multiplexing dual-function meta-lens device, which is designed using the design method of the polarization multiplexing dual-function meta-lens device provided in the first aspect of the present invention, and includes: a substrate and a nano-array arranged on the A surface of the substrate, which is used for bright field imaging or edge-enhanced imaging of a target object under illumination of orthogonal polarization incident light.

[0133] The related technical scheme is the same as the design method of the polarization multiplexing dual-function meta-lens device provided in the first aspect of the present invention, and will not be described in detail here.

[0134] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A design method for a monolithic polarization multiplexing dual-function meta-lens device, characterized in that: include: The nanoarray is arranged on the A surface of the substrate; the nanoarray includes: anisotropic nanounits that are periodically arranged, have the same height, and have a sub-wavelength size; the cross section of the nanounit parallel to the A surface is C2 symmetrical, and the major axis and the minor axis of the cross section are perpendicular to each other; 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; 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 surface 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, forming a rotation angle distribution θ' of the nanometer array, θ' satisfies:

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: 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: Each nanometer unit is rotated counterclockwise on the A surface with its lattice center as the rotation center, forming a rotation angle distribution θ' of the nanometer array, θ' satisfies:

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 for 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 plane with its lattice center 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 And the rotation angle distribution θ' satisfies, The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * 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 plane with its lattice center 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 And the rotation angle distribution θ' satisfies The polarization azimuths of left-handed elliptically polarized light and right-handed elliptically polarized light are both ω, and 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 both * is the conjugation symbol.

7. The design method of the polarization multiplexing dual-function meta-lens device according to any one of claims 1 to 6, characterized in that: In the polar coordinate system corresponding to the xy coordinate system, the phase distribution Phase value at position (r,θ) and phase distribution Phase value at position (r,θ) They are: Wherein, λ0 is the target operating wavelength of the meta-lens device; f is the target focal length of the meta-lens device; C is an arbitrary constant; l 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, characterized in that: The shape of the nanometer unit is a rectangular column, an elliptical column or a cross column.

9. The design method of the polarization multiplexing dual-function meta-lens device according to any one of claims 1 to 6, characterized in that: 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 band of the device.

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

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