Visible light dual-wavelength polarization multiplexing metasurface hologram and preparation method thereof

Abstract

The invention discloses a visible light dual-wavelength polarization multiplexing metasurface hologram and a preparation method thereof, and relates to the technical field of micro-nano manufacturing. The super-surface hologram is composed of a super-atom array based on a nanoimprint technology, wherein the period of the super-atom array in the x direction and the period of the super-atom array in the y direction are 450 nm, and the height of the super-atom array is 800 nm. In the superatom array, all superatoms are of cuboid columnar structures, and a main body is composed of a polymer doped with titanium dioxide nanoparticles; the size and the position of each super atom are determined according to a GS algorithm; the GS algorithm is used for calculating the phase information of the target image under the polarized light with the corresponding wavelength; the wavelength polarized light comprises X polarized light of 532 nm and Y polarized light of 671 nm. According to the method, the problems of long manufacturing process period, small scale, high cost and the like of a traditional metasurface device can be solved, and a new development thought is provided for a multi-color imaging technology based on metasurface holography.

Description

Technical Field

[0001] The present invention relates to the field of micro-nano manufacturing technology, and in particular to a visible light dual-wavelength polarization multiplexing metasurface hologram and a preparation method thereof. Background Art

[0002] Metasurface is a new type of subwavelength structure that can flexibly control the amplitude, polarization and phase of electromagnetic waves at the microscopic level. In the field of optics, metasurfaces are widely used, such as superlenses, holographic imaging, invisible cloaks, absorption enhancement devices, etc. As an emerging device with information preservation, information encryption and information transmission functions, metasurface holograms can break through the various limitations of traditional holographic imaging devices, such as small field of view and large volume. However, most metasurface holograms have a prominent problem, that is, they can only work at a specific single wavelength and do not have multi-wavelength imaging capabilities.

[0003] Moreover, metasurfaces working in the visible light range are usually prepared based on pure titanium dioxide (TiO2) because of its high refractive index and low extinction coefficient. The traditional titanium dioxide metasurface manufacturing process can be summarized as follows: first, a TiO2 film is grown on a substrate using physical vapor deposition (PVD); then, an etching hard mask is manufactured by electron beam lithography (EBL); and then the required columnar structure is etched by ion beam etching (IBE) and other methods. It is not difficult to see that the above manufacturing process has a long cycle, many steps, and high cost, which is not conducive to the mass production and large-scale promotion of metasurface holograms. Summary of the invention

[0004] The purpose of the present invention is to provide a visible light dual-wavelength polarization multiplexing metasurface hologram and a preparation method thereof, which can solve the problems of long manufacturing process cycle, small scale and high cost of traditional metasurface devices, and provide new development ideas for multi-color imaging technology based on metasurface holography.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] A visible light dual-wavelength polarization multiplexing metasurface hologram, comprising: based on nanoimprint technology, composed of a superatom array with a period of 450nm in the x-direction and y-direction and a height of 800nm; in the superatom array, all superatoms are rectangular columnar structures, and the main body is composed of a polymer doped with titanium dioxide nanoparticles; the size and position of each superatom are determined according to a GS algorithm; the GS algorithm is used to calculate the phase information of a target image under corresponding wavelength polarized light; the wavelength polarized light includes 532nm X-polarized light and 671nm Y-polarized light.

[0007] Optionally, the overall length and width of the metasurface hologram are 53.55 μm and 45.45 μm, respectively.

[0008] Optionally, the length and width of the superatom are between 100 and 380 nm.

[0009] The present invention also provides a method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram, comprising:

[0010] Etching the silicon substrate to obtain a super-surface hologram silicon master mold;

[0011] Performing a surface fluorination treatment on the silicon master mold;

[0012] Spin coating and curing hPDMS and PDMS on the fluorinated silicon master mold in sequence, and separating the fully cured silicon master mold and PDMS sub-mold to obtain the corresponding negative structure sub-mold;

[0013] Spin-coat the imprint glue on the sub-mold, then invert the two on the supporting substrate, then apply downward pressure on the top of the silicon mother mold, and perform UV curing at the same time; the imprint glue is a polymer doped with titanium dioxide nanoparticles; the supporting substrate is a glass substrate;

[0014] The daughter mold is peeled off to obtain a replica with the same structure as the silicon mother mold, thus completing the preparation of the visible light dual-wavelength polarization multiplexing metasurface hologram.

[0015] Optionally, etching the silicon substrate to obtain a supersurface hologram silicon master mold specifically includes:

[0016] In the first step, the silicon substrate was immersed in acetone, isopropanol and deionized water for 10 min respectively, and then N 2 Blow dry both sides of the silicon substrate;

[0017] In the second step, the photoresist PMMA was spin-coated on the surface of the silicon substrate at a speed of 2000 rpm, and then baked at 180 ° C for 300 s;

[0018] The third step is to expose PMMA using electron beam lithography, followed by development to obtain an etching mask;

[0019] The fourth step is to use an inductively coupled plasma reactive ion etching device to etch the silicon substrate, and then use a plasma degumming machine to remove the residual PMMA on the surface to obtain a silicon master mold;

[0020] In the fifth step, the silicon master mold was immersed in acetone, isopropanol and deionized water for 10 min respectively, and then 2 The front and back sides of the silicon master mold are blown dry to obtain a super surface hologram silicon master mold.

[0021] Optionally, the silicon master mold is subjected to a surface fluorination treatment, specifically comprising:

[0022] In the first step, take an appropriate amount of anti-sticking reagent perfluorooctyltrichlorosilane in an evaporating dish;

[0023] The second step is to place the evaporating dish and the silicon master mold bombarded with oxygen plasma in a vacuum box;

[0024] In the third step, under a vacuum environment, perfluorooctyltrichlorosilane volatilizes and adheres to the surface of the silicon master mold to achieve surface hydrophobicity.

[0025] Optionally, hPDMS and PDMS are sequentially spin-coated and cured on the fluorinated silicon master mold, and the completely cured silicon master mold and PDMS sub-mold are separated to obtain a corresponding negative structure sub-mold, specifically comprising:

[0026] In the first step, the fluorinated silicon master mold is fixed on the supporting substrate using a high temperature tape;

[0027] In the second step, the hPDMS precursor was spin-coated on the silicon master mold at a speed of 1000 rpm and then baked in an oven at 70 °C for 2 h to achieve semi-curing;

[0028] In the third step, the PDMS precursor was spin-coated on the semi-cured hPDMS at a speed of 1000 rpm, and then baked in an oven at 100 °C for 2 h to achieve complete curing of hPDMS and PDMS;

[0029] The fourth step is to separate the silicon master mold and the PDMS sub-mold, and then rinse the PDMS sub-mold with isopropyl alcohol and deionized water respectively, and then rinse with N 2 The front and back sides of the PDMS sub-mold are blown dry, and finally subjected to fluorination treatment to obtain the corresponding negative structure sub-mold.

[0030] Optionally, the imprinting glue is spin-coated on the daughter mold, and then both are inverted on the supporting substrate, and then downward pressure is applied on the top of the silicon mother mold, and UV curing is performed at the same time, specifically including:

[0031] First, the embossing glue was spin-coated on the surface of the PDMS sub-mold at a speed of 1800 rpm, and then placed in a vacuum box for 5 minutes to remove the bubbles in the contact surface between the embossing glue and the PDMS sub-mold;

[0032] PMMA was first spin-coated on a glass substrate at a speed of 2000 rpm and then baked in an oven at 100 °C for 2 min to improve the adhesion between the subsequent imprinting glue and the glass substrate;

[0033] The sub-mold was placed upside down on a glass substrate, and UV light exposure was performed while applying a pressure of 50 kPa to achieve curing of the imprint glue.

[0034] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0035] The present invention discloses a visible light dual-wavelength polarization multiplexing metasurface hologram and a preparation method thereof, wherein the metasurface hologram comprises a superatom array based on nanoimprint technology, with a period of 450nm in the x-direction and y-direction and a height of 800nm; in the superatom array, all superatoms are rectangular columnar structures, and the main body is composed of a polymer doped with titanium dioxide nanoparticles; the size and position of each superatom are determined according to the GS algorithm; the GS algorithm is used to calculate the phase information of the target image under the corresponding wavelength polarized light; the wavelength polarized light includes 532nm X-polarized light and 671nm Y-polarized light. The present invention can solve the problems of long manufacturing process cycle, small scale, high cost, etc. of traditional metasurface devices, and provide new development ideas for multi-color imaging technology based on metasurface holography. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0037] Figure 1 is a three-dimensional schematic diagram of a supersurface hologram of the present invention;

[0038] Figure 2 is a three-dimensional schematic diagram of a single superatom in this embodiment;

[0039] Figure 3 This is a schematic diagram of the working principle of the metasurface hologram in this embodiment;

[0040] Figure 4The far-field imaging diagram of the metasurface hologram simulated in this embodiment under the incidence of different wavelengths and different linear polarization lights; wherein, part (a) is the far-field energy distribution diagram of 532nm wavelength x-linear polarization light passing through the metasurface hologram, and part (b) is the far-field energy distribution diagram of 671nm wavelength y-linear polarization light passing through the metasurface hologram;

[0041] Figure 5 Schematic diagram of the principle of fluorination treatment on the surface of the silicon master mold (or PDMS daughter mold) in this embodiment;

[0042] Figure 6 4 is a flow chart of the reverse nanoimprinting process in this embodiment. DETAILED DESCRIPTION

[0043] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0044] The purpose of the present invention is to provide a visible light dual-wavelength polarization multiplexing metasurface hologram and a preparation method thereof, which can solve the problems of long manufacturing process cycle, small scale and high cost of traditional metasurface devices, and provide new development ideas for multi-color imaging technology based on metasurface holography.

[0045] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0046] like Figure 1 As shown, the present invention provides a visible light dual-wavelength polarization multiplexing metasurface hologram, which can form different images under 532nm X-polarized light and 671nm Y-polarized light, respectively, laying the foundation for the large-scale application of metasurface holograms.

[0047] The metasurface hologram is composed of periodically arranged columnar structures, and a single columnar structure is called a metaatom. The metaatoms at different positions correspond to the actual transmission phase of the position. Unlike traditional photolithography, the nanoimprint process has higher compatibility with the substrate, so its material can be glass or flexible plastic, and its shape can be flat or curved.

[0048] As a specific implementation, the structure and preparation process of the metasurface hologram include:

[0049] The first step is to obtain a silicon master mold of the supersurface hologram by etching the silicon substrate. The second step is to perform surface fluorination treatment on the silicon master mold to facilitate subsequent demolding. The third step is to spin-coat hPDMS on the silicon master mold in sequence, and then bake and cure. The fourth step is to spin-coat PDMS on the hPDMS surface, and then bake and cure to obtain the corresponding negative structure sub-mold. The fifth step is to apply TiO doped 2 The nanoparticle polymer is spin-coated on the sub-mold, and then both are inverted on a supporting substrate, and then downward pressure is applied to the top of the silicon master mold while UV curing is performed. Finally, the sub-mold is peeled off to obtain a replica with the same structure as the silicon master mold.

[0050] The dual wavelengths refer to 532nm and 671nm, and polarization multiplexing refers to the imaging of linearly polarized light beams in the X and Y directions. The super-atom is a rectangular columnar structure on the surface of the substrate. Super-atoms of different sizes and shapes have different optical responses to incident light linearly polarized in the X and Y directions, so the transmission phases in the X and Y directions can be independently controlled. All the super-atoms have the same height and arrangement period. All the super-atoms are dielectric materials.

[0051] For the size and position of the meta-atom, the GS (Gerchberg-Saxton) algorithm is used to extract the phase information of the target image A under 532nm X-polarized light and the phase information of the target image B under 671nm Y-polarized light. The actual transmission phase under the incidence of two wavelengths of polarized light is obtained by simulating the meta-atom. Furthermore, the designed metasurface must contain the phase information of the two target images at the same time. This means that each meta-atom must contain two phase information: the first is the phase information of the target image A at this position under the incidence of 532nm X-polarized light. The second is the phase information of the target image B at this position under the incidence of 671nm Y-polarized light. Based on the above phase information, suitable meta-atoms are selected at different positions for placement, and finally a complete metasurface hologram is formed.

[0052] As a more detailed preparation process, the etching process mainly includes: relying on electron beam lithography (EBL) technology to obtain an etching mask corresponding to the desired super surface hologram on the surface of the silicon substrate. Relying on inductively coupled plasma etching (ICP) technology, a super surface hologram is etched on the surface of the silicon substrate, which is the silicon master mold. Then the surface of the silicon master mold needs to be fluorinated to facilitate subsequent demolding. The fluorination treatment process mainly includes: taking an appropriate amount of anti-sticking reagent perfluorooctyltrichlorosilane in an evaporating dish, and placing the evaporating dish together with the silicon master mold (or sub-mold) bombarded by oxygen plasma in a vacuum box. Under a vacuum environment, perfluorooctyltrichlorosilane volatilizes and adheres to the surface of the silicon master mold (or sub-mold), and surface fluorination can be achieved. The sub-mold production process includes: spin coating the hPDMS precursor on the silicon master mold, then baking until semi-cured, then spin coating the PDMS precursor on the semi-cured hPDMS, and finally baking until both are completely cured. Remove the silicon master mold, and then perform the aforementioned fluorination treatment on the sub-mold. A polymer doped with titanium dioxide nanoparticles, i.e., an imprinting glue, is spin-coated on the front of the sub-mold. The residual layer thickness of the imprinting glue can be adjusted by adjusting the coating rate and time. The reverse nanoimprinting process includes: placing the sub-mold upside down on a glass substrate, applying appropriate downward pressure and exposing it to ultraviolet light to cure the imprinting glue. Finally, the sub-mold is removed to obtain a replica of the silicon master mold, which is the desired metasurface hologram.

[0053] In the above process, when the liquid fluorine-based anti-adhesive agent and the silicon master mold (or PDMS sub-mold) after plasma bombardment are placed in a vacuum environment at the same time, the anti-adhesive agent will volatilize and adhere to the surface of the silicon master mold (or PDMS sub-mold), thereby achieving an anti-adhesive effect. In addition, the PDMS sub-mold is a double-layer step structure, in which the hPDMS with a high Young's modulus mold is directly in contact with the silicon master mold, and the surface of the hPDMS is covered by PDMS.

[0054] Therefore, this technical solution has the following beneficial effects:

[0055] (1) The cuboid superatom used in the present invention has a high degree of design freedom and can independently regulate the transmission phase of light with different polarizations, thereby realizing the polarization multiplexing function.

[0056] (2) The present invention realizes dual-color holographic display based on 532nm X-polarized light and 671nm Y-polarized light, thereby enriching the information storage and other functions of the metasurface hologram.

[0057] (3) Based on the polarization control principle, the present invention realizes the visible light dual-wavelength polarization multiplexing function through a single-layer metasurface. Compared with traditional imaging systems, it is smaller in size, less complex, and more integrated.

[0058] (4) The present invention uses a polymer doped with titanium dioxide nanoparticles as an embossing glue. The good fluidity of the material lays a foundation for the direct embossing of the metasurface hologram. At the same time, the material has a high refractive index and a low extinction coefficient in the visible light band, which provides a guarantee for the imaging quality of the metasurface hologram.

[0059] (5) The present invention adopts a simple and low-cost surface fluorination method to achieve hydrophobicity of silicon master molds and sub-molds. The specific operation process is as follows: the first step is to take an appropriate amount of anti-sticking reagent perfluorooctyltrichlorosilane in an evaporating dish. The second step is to place the evaporating dish together with the silicon master mold (or sub-mold) bombarded with oxygen plasma in a vacuum box. The third step is that in a vacuum environment, perfluorooctyltrichlorosilane volatilizes and adheres to the surface of the silicon master mold (or sub-mold), thereby achieving surface fluorination.

[0060] (6) The present invention uses a double-layer PDMS as a sub-mold. The hPDMS that is in direct contact with the silicon master mold has a higher Young's modulus and is not easily deformed when imprinting a structure with a high aspect ratio. The PDMS layer covers the entire hPDMS layer and plays a supporting and protective role during the demolding process.

[0061] (7) The present invention adopts reverse embossing. The specific operation process is as follows: the first step is to place the front side of the sub-mold (i.e., the surface with the structure) facing upward on the spin coater. The second step is to use a glue-tipped dropper to drop an appropriate amount of embossing glue on the front side of the sub-mold, and to accurately control the thickness of the embossing glue on the front side of the sub-mold by adjusting the spin coating speed and time, that is, the thickness of the residual layer. The third step is to cover the front side of the sub-mold with a glass substrate for embossing. The traditional forward embossing process is to first spin-coat the embossing glue on the glass substrate, and then press the front side of the sub-mold downward on the glass substrate for embossing. In this process, the residual layer is too thick, which is not conducive to the final imaging quality of the metasurface hologram.

[0062] Based on the above technical solution, the following specific embodiments are provided.

[0063] like Figure 1 As shown in the figure, the overall length and width of the visible light dual-wavelength polarization multiplexing metasurface hologram based on nanoimprint technology are 53.55μm and 45.45μm respectively. Its upper surface is composed of a superatom array with a period of 450nm in the x- and y-directions and a height of 800nm. The cross-sections of all superatoms are rectangular, which makes them have different optical responses to linearly polarized incident light in the x- and y-directions. Therefore, by changing the size of the superatom cross-section, the transmission phase of linearly polarized light in the x- and y-directions can be independently controlled. Figure 2 As shown in Figure 1, the superatom body is composed of a polymer with titanium dioxide nanoparticles distributed inside, and the length and width of its cross section range from 100 to 380 nm. Figure 3As shown, the metasurface hologram can realize wavelength polarization multiplexing for 532nm x-polarized incident light and 671nm y-polarized incident light, presenting two images of different colors in the plane. Figure 2 and Figure 3 In the figure, λ represents the wavelength of the incident light, P represents the superatom period, H represents the height of the superatom structure, W represents the superatom width, and L represents the superatom length.

[0064] The GS (Gerchberg-Saxton) algorithm is used to extract the phase information of the two target images under 532nm wavelength x-polarized light and 671nm wavelength y-polarized light. Through simulation calculation, the actual transmission phase of all meta-atoms under 532nm x-polarized light and 671nm y-polarized light is obtained. According to the phase information of the two images, meta-atoms with the same phase information are placed in different positions in turn until a complete metasurface hologram is formed. The far-field energy distribution of 532nm wavelength x-polarized light passing through the metasurface hologram is shown in the figure below. Figure 4 As shown in part (a), the far-field energy distribution of 671nm wavelength y-polarized light passing through the metasurface hologram is as follows: Figure 4 As shown in part (b).

[0065] Based on the size of each superatom, the silicon substrate was etched to obtain the supersurface hologram silicon master mold. The detailed process is as follows: In the first step, the silicon substrate was soaked in acetone, isopropanol and deionized water for 10 minutes respectively, and then N 2 Blow dry both sides of the silicon substrate. The second step is to spin-coat the photoresist PMMA on the surface of the silicon substrate at a speed of 2000 rpm, and then bake it at 180°C for 300s. The third step is to expose PMMA using electron beam lithography (EBL), and then develop to obtain an etching mask. The fourth step is to etch the silicon substrate using an inductively coupled plasma reactive ion etching (ICP-RIE) device, and then use a plasma stripper to remove the residual PMMA on the surface to obtain a silicon master mold. The fifth step is to soak the silicon master mold in acetone, isopropanol and deionized water for 10 minutes, and then use N 2 Blow dry both sides of the silicon master mold.

[0066] Before using the silicon master mold (or daughter mold), it is necessary to perform a surface fluorination treatment (i.e., surface hydrophobization treatment) to facilitate subsequent demolding. The first step is to take an appropriate amount of anti-sticking reagent perfluorooctyltrichlorosilane in an evaporating dish. The second step is to place the evaporating dish and the silicon master mold (or daughter mold) bombarded with oxygen plasma in a vacuum box. Figure 5In the third step, under vacuum, perfluorooctyltrichlorosilane volatilizes and adheres to the surface of the silicon master mold (or daughter mold), thereby achieving surface hydrophobicity.

[0067] Figure 6 Schematic diagram of the reverse nanoimprinting process. The first step is to fix the fluorinated silicon master mold on the supporting substrate (not shown in the figure) using high-temperature tape. The second step is to spin-coat the hPDMS precursor on the silicon master mold at a speed of 1000 rpm, and then bake it in a 70°C oven for 2 hours to achieve semi-curing. The third step is to spin-coat the PDMS precursor on the semi-cured hPDMS at a speed of 1000 rpm, and then bake it in a 100°C oven for 2 hours to achieve complete curing of hPDMS and PDMS. The fourth step is to separate the silicon master mold and the PDMS sub-mold, and then rinse the PDMS sub-mold with isopropanol and deionized water respectively, and then blow dry the front and back sides of the PDMS sub-mold with N2, and finally perform fluorination treatment. The fifth step is to spin-coat the imprint glue (that is, a polymer doped with titanium dioxide nanoparticles) on the surface of the PDMS sub-mold at a speed of 1800 rpm, and then place it in a vacuum box for 5 minutes to discharge bubbles in the contact surface between the imprint glue and the PDMS sub-mold. In the sixth step, PMMA is first spin-coated on the glass substrate at a speed of 2000 rpm, and then baked in a 100°C oven for 2 minutes to improve the adhesion between the subsequent imprint glue and the glass substrate. In the seventh step, the sub-mold is inverted on the glass substrate, and a pressure of 50 kPa is applied while UV exposure is performed to achieve the curing of the imprint glue. In the eighth step, the glass substrate and the PDMS sub-mold are separated, and the replica will remain on the surface of the glass substrate.

[0068] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0069] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A visible light dual-wavelength polarization multiplexing metasurface hologram, characterized in that: include: Based on nanoimprint technology, it is composed of a superatom array with a period of 450nm in the x-direction and y-direction and a height of 800nm; in the superatom array, all superatoms are rectangular columnar structures, and the main body is composed of a polymer doped with titanium dioxide nanoparticles; the size and position of each superatom are determined according to the GS algorithm; the GS algorithm is used to calculate the phase information of the target image under the corresponding wavelength polarized light; the wavelength polarized light includes 532nm X-polarized light and 671nm Y-polarized light.

2. The visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 1, characterized in that: The overall length and width of the metasurface hologram are 53.55 μm and 45.45 μm, respectively.

3. The visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 1, characterized in that: The length and width of the superatom are between 100 and 380 nm.

4. A method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram, characterized in that: include: Etching the silicon substrate to obtain a super-surface hologram silicon master mold; Performing a surface fluorination treatment on the silicon master mold; Spin coating and curing hPDMS and PDMS on the fluorinated silicon master mold in sequence, and separating the fully cured silicon master mold and PDMS sub-mold to obtain the corresponding negative structure sub-mold; Spin-coat the imprint glue on the sub-mold, then invert the two on the supporting substrate, then apply downward pressure on the top of the silicon mother mold, and perform UV curing at the same time; the imprint glue is a polymer doped with titanium dioxide nanoparticles; the supporting substrate is a glass substrate; The daughter mold is peeled off to obtain a replica with the same structure as the silicon mother mold, thus completing the preparation of the visible light dual-wavelength polarization multiplexing metasurface hologram.

5. The method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 4, characterized in that: The silicon substrate is etched to obtain a super-surface hologram silicon master mold, which specifically includes: In the first step, the silicon substrate was immersed in acetone, isopropanol and deionized water for 10 min respectively, and then the front and back sides of the silicon substrate were blown dry with N2; In the second step, the photoresist PMMA was spin-coated on the surface of the silicon substrate at a speed of 2000 rpm, and then baked at 180 ° C for 300 s; The third step is to expose PMMA using electron beam lithography, followed by development to obtain an etching mask; The fourth step is to use an inductively coupled plasma reactive ion etching device to etch the silicon substrate, and then use a plasma degumming machine to remove the residual PMMA on the surface to obtain a silicon master mold; In the fifth step, the silicon master mold is immersed in acetone, isopropanol and deionized water for 10 minutes respectively, and then the front and back sides of the silicon master mold are blown dry with N2 to obtain the supersurface hologram silicon master mold.

6. The method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 4, characterized in that: The silicon master mold is subjected to a surface fluorination treatment, specifically comprising: In the first step, take an appropriate amount of anti-sticking reagent perfluorooctyltrichlorosilane in an evaporating dish; The second step is to place the evaporating dish and the silicon master mold bombarded with oxygen plasma in a vacuum box; In the third step, under a vacuum environment, perfluorooctyltrichlorosilane volatilizes and adheres to the surface of the silicon master mold to achieve surface hydrophobicity.

7. The method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 4, characterized in that: Sequentially spin coating and curing hPDMS and PDMS on the fluorinated silicon master mold, and separating the fully cured silicon master mold and PDMS sub-mold to obtain the corresponding negative structure sub-mold, specifically including: In the first step, the fluorinated silicon master mold is fixed on the supporting substrate using a high temperature tape; In the second step, the hPDMS precursor was spin-coated on the silicon master mold at a speed of 1000 rpm and then baked in an oven at 70 °C for 2 h to achieve semi-curing; In the third step, the PDMS precursor was spin-coated on the semi-cured hPDMS at a speed of 1000 rpm, and then baked in an oven at 100 °C for 2 h to achieve complete curing of hPDMS and PDMS; The fourth step is to separate the silicon master mold and the PDMS sub-mold, then rinse the PDMS sub-mold with isopropyl alcohol and deionized water respectively, then blow dry both sides of the PDMS sub-mold with N2, and finally perform fluorination treatment to obtain the corresponding negative structure sub-mold.

8. The method for preparing a visible light dual-wavelength polarization multiplexing metasurface hologram according to claim 4, characterized in that: The imprint glue is spin-coated on the daughter mold, and then both are inverted on the supporting substrate. Then downward pressure is applied on the top of the silicon mother mold, and UV curing is performed at the same time, which includes: First, the embossing glue was spin-coated on the surface of the PDMS sub-mold at a speed of 1800 rpm, and then placed in a vacuum box for 5 minutes to remove the bubbles in the contact surface between the embossing glue and the PDMS sub-mold; PMMA was first spin-coated on a glass substrate at a speed of 2000 rpm and then baked in an oven at 100 °C for 2 min to improve the adhesion between the subsequent imprinting glue and the glass substrate; The sub-mold was placed upside down on a glass substrate, and UV light exposure was performed while applying a pressure of 50 kPa to achieve curing of the imprint glue.

Images