WO2021031807A1 - Polarization multi-channel metasurface optical element and method for reconstructing full color holographic image - Google Patents

Polarization multi-channel metasurface optical element and method for reconstructing full color holographic image Download PDF

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WO2021031807A1
WO2021031807A1 PCT/CN2020/105245 CN2020105245W WO2021031807A1 WO 2021031807 A1 WO2021031807 A1 WO 2021031807A1 CN 2020105245 W CN2020105245 W CN 2020105245W WO 2021031807 A1 WO2021031807 A1 WO 2021031807A1
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channel
polarization
metasurface
nano
pillars
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PCT/CN2020/105245
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French (fr)
Chinese (zh)
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胡跃强
段辉高
李苓
罗栩豪
李鑫
宋强
马国斌
徐晓波
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深圳珑璟光电技术有限公司
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    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
    • G02B27/28—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 for polarising
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/0005—Adaptation of holography to specific applications
    • G03H1/0011—Adaptation of holography to specific applications for security or authentication
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G03H1/2645—Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03H—HOLOGRAPHIC PROCESSES OR APPARATUS
    • G03H1/00—Holographic processes or apparatus using light, infrared or ultraviolet waves for obtaining holograms or for obtaining an image from them; Details peculiar thereto
    • G03H1/26—Processes or apparatus specially adapted to produce multiple sub- holograms or to obtain images from them, e.g. multicolour technique
    • G03H1/2645—Multiplexing processes, e.g. aperture, shift, or wavefront multiplexing
    • G03H2001/267—Polarisation multiplexing

Definitions

  • the present invention relates to the field of micro-nano optics and optical holography, in particular to a polarization multi-channel superstructure surface optical element and a method for reconstructing a full-color holographic image.
  • Metasurfaces can allow people to adjust the phase, amplitude, and polarization of light waves arbitrarily in a two-dimensional plane, giving them great freedom in designing new optical components. Therefore, in recent years, lenses based on metasurfaces, light deflectors, polarization converters, and holographic metasurfaces have all been proposed and extensively studied. Among them, due to the characteristics of large field of view, high density, high resolution, etc., the holographic technology based on meta-surface has received widespread attention. Based on this, various multi-channel meta-surface holograms have been developed. Among them, interlaced unit, multi-plane Strategies such as multi-angle and multi-angle are usually used in wavelength multi-channel applications, such as color holography or multi-wavelength hyperlenses.
  • the meta-surface is characterized by sub-wavelength adjustment of polarization.
  • the multi-channel device based on two orthogonal incident polarization states can theoretically completely suppress the crosstalk between channels and realize dual Functional application.
  • the previous PB-phase-based interlaced units or anisotropic structural surfaces have not yet fully explored the degree of freedom of the birefringent metasurface unit, and cannot realize the encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization.
  • Channel holography is compared with the traditional DOE element.
  • the purpose of the present invention is to provide a polarization multi-channel meta-surface optical element and a method for reconstructing a full-color holographic image, which can realize encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization multi-channel holography.
  • the present invention provides the following solutions:
  • a polarized multi-channel metasurface optical element comprising: a dielectric substrate and an anisotropic dielectric nanostructure array, the anisotropic dielectric nanostructure array is arranged on the dielectric substrate, and the anisotropic The dielectric nanostructure array contains multiple nanopillars.
  • the dielectric substrate is a quartz substrate, an alumina substrate, a glass substrate or a diamond substrate.
  • the nanopillars are rectangular nanopillars, elliptical nanopillars, asymmetric cross-shaped nanopillars or L-shaped nanopillars.
  • the structural material of the nano-pillars is TiO2, HfO2, ZrO2, GaN, Si2N3, Si, GaAs, ZnS or AlN.
  • the height range of the nanopillars is 200nm-1500nm
  • the size of the nanopillars on the surface of the dielectric substrate is 20nm-1000nm
  • the nanopillars are arbitrarily arranged on the surface of the dielectric substrate.
  • a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element including:
  • the Jones matrix includes three independent phase information, and the three independent phase information is independently reconstructed by three different polarization combinations of incident light and outgoing light;
  • the three primary color grayscale images are matched with the information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image.
  • said matching the three primary color grayscale images to information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image specifically includes:
  • the three primary color grayscale images are matched with the information in the polarization channel using a color difference pre-compensation algorithm and a distortion pre-compensation algorithm to obtain a full-color holographic image.
  • the present invention discloses the following technical effects:
  • the polarized multi-channel metasurface optical element proposed in the present invention is composed of a dielectric substrate and an anisotropic dielectric nanostructure array on it, and the structure parameters (in-plane size and in-plane angle) of the nanostructures at various positions are adjusted and controlled. Realize the encoding of holographic images with up to three independent polarization channels, and the meta-surface has broadband usable properties. By choosing different dielectric materials, it can achieve high resolution in different wavelength bands (such as infrared, visible and ultraviolet). Efficient multi-channel polarization multi-channel holography.
  • a full-color holographic display with near zero crosstalk can be realized.
  • the multi-channel polarization multi-channel metasurface proposed by the present invention can be used for polarization information encryption and data anti-counterfeiting on the one hand; in addition, the element has a planar two-dimensional structure, simple structure, lightweight and thin, and can be mass-produced; finally, the color hologram Display technology has the advantages of super large field of view, near zero crosstalk, super high resolution, etc., and can be widely used in industries such as holographic projection and near-eye display.
  • Figure 1 is a schematic diagram of the composition of the polarized multi-channel metasurface optical element of the present invention
  • Fig. 2 is a schematic diagram of a metasurface for realizing polarization multi-channel full-color holography according to the present invention
  • Fig. 3 is a flowchart of a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element of the present invention
  • Figure 4 is a schematic diagram of a single unit of the metasurface of the present invention.
  • Figure 5 is the phase distribution and transmittance distribution of a single unit of the present invention under x-polarized light
  • Figure 6 is a scanning electron micrograph of the metasurface in Example 1.
  • FIG. 7 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 1;
  • Figure 8 is a scanning electron micrograph of the metasurface in Example 2.
  • Example 9 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 2.
  • Figure 10 is a schematic diagram of color holographic coding in Embodiment 3.
  • Example 11 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 3.
  • the purpose of the present invention is to provide a polarization multi-channel meta-surface optical element and a method for reconstructing a full-color holographic image, which can realize encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization multi-channel holography.
  • Figure 1 is a schematic diagram of the composition of the polarized multi-channel metasurface optical element of the present invention.
  • a polarization multi-channel metasurface optical element includes: a dielectric substrate 1 and an anisotropic dielectric nanostructure array, and the anisotropic dielectric nanostructure array is disposed on the dielectric substrate 1.
  • the anisotropic dielectric nanostructure array includes a plurality of nanopillars 2.
  • the dielectric substrate 1 is a quartz substrate, an alumina substrate, a glass substrate or a diamond substrate.
  • the nano-pillars 2 adopt rectangular nano-pillars, elliptical nano-pillars, asymmetric cross-shaped nano-pillars or L-shaped nano-pillars.
  • the structural material of the nano-pillar 2 is TiO2, HfO2, ZrO2, GaN, Si2N3, Si, GaAs, ZnS or AlN.
  • the height range of the nanopillars 2 is 200nm-1500nm, the size of the nanopillars 2 on the surface of the dielectric substrate is 20nm-1000nm, and the nanopillars are arbitrarily arranged on the surface of the dielectric substrate.
  • a full-color holographic image acquisition system includes: a polarization multi-channel metasurface optical element, a light source, and a receiving screen.
  • the polarization multi-channel metasurface optical element includes a dielectric substrate 1 and an anisotropic dielectric nanostructure array.
  • the light source is located on the side of the dielectric substrate 1
  • the receiving screen is located on the side of the anisotropic dielectric nanostructure array, and the light emitted by the light source passes through the dielectric substrate 1 and the anisotropic
  • the array of dielectric nanostructures reaches the receiving screen to form a full-color hologram.
  • the light source includes a blue light source with incident y-axis polarization, a green light source with incident x-axis polarization, and a red light source with incident x-axis polarization.
  • the full-color hologram includes a blue holographic component, a green holographic component, and a red holographic component.
  • Fig. 2 is a schematic diagram of the meta-surface for realizing polarization multi-channel full-color holography according to the present invention.
  • 1 is the dielectric substrate
  • 2 is the nano-pillar
  • 3 is the incident y-polarized blue light source
  • 4 is the incident x-polarized green light source
  • 5 is the incident x-polarized red light source
  • 6 is a single unit
  • 7 is the exit X-polarized red light
  • 8 emits y-polarized green light
  • 9 emits y-polarized blue light
  • 10 is a full-color hologram
  • 11 is a red holographic component
  • 12 is a green holographic component
  • 13 is a blue holographic component.
  • Fig. 3 is a flowchart of a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element of the present invention.
  • a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element includes:
  • Step 101 Obtain the long axis size, the short axis size, and the in-plane angle of the nano column on the surface of the dielectric substrate, wherein the long axis size, the short axis size, and the in-plane angle are within a unit period Arbitrary regulation
  • Step 102 By periodically arranging the nanostructure units with different major axis sizes, minor axis sizes and in-plane angles on the dielectric substrate to construct Jones matrices with different positions to complete three independent plane phase distributions
  • the Jones matrix contains three independent phase information, and the three independent phase information is independently reconstructed by three different polarization combinations of incident light and outgoing light;
  • Step 103 Calculate the phase distribution of the gray image information of the three primary colors through the holographic phase recovery algorithm, and couple it to three independent polarization channels;
  • Step 104 Match the three primary color grayscale images with the information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image, which specifically includes:
  • the three primary color grayscale images are matched with the information in the polarization channel using a color difference pre-compensation algorithm and a distortion pre-compensation algorithm to obtain a full-color holographic image.
  • the birefringent unit can construct an arbitrary symmetric Jones matrix by controlling the phase adjustment of the long axis and the short axis and the in-plane rotation angle. In this way, a single nanostructure can control the polarization and phase arbitrarily, and the matrix contains three different phases, which can be independently reconstructed through different incident and exit polarization combinations.
  • a single anisotropic sub-wavelength nanostructure can be regarded as a birefringent unit.
  • Any Jones matrix can be constructed by arbitrarily selecting the size of the major axis and the minor axis and the in-plane rotation angle, so up to three independent phases can be achieved
  • the encoding of three independent phases can be achieved through the combination of incident and outgoing polarization.
  • nanostructures of different sizes at different positions to realize the design phase distribution it is possible to construct a metasurface element that realizes the encoding of three independent information.
  • polarization multi-channel switchable holographic encryption can be realized.
  • the element is used within a certain wavelength range.
  • the three primary color components of a color image are coupled to three independent polarization channels, and a full-color holographic display can be realized through the combination of wavelength and incident/outgoing polarization.
  • each unit can be expressed by Jones matrix
  • ⁇ x and ⁇ y are the phase delays of the two axes, which are determined by the structural dimensions D 1 and D 2 respectively; R is expressed by the in-plane angle ⁇ , and R is the rotation matrix.
  • the three independent phases ⁇ 1 , ⁇ 2 , and ⁇ 3 can be obtained by solving equation (3) to obtain ⁇ x , ⁇ y , ⁇ , and then the corresponding three structural parameters D 1 , D 2, ⁇ can be obtained.
  • the proposed metasurface can encode three independent phase information, the three independent information can be combined to obtain Different combinations of information.
  • Figure 2 shows a schematic diagram of a metasurface for realizing polarization multi-channel full-color holography.
  • the surface is realized by a TiO2 rectangular nanopillar array with three independent structural parameters: length (D 1 ), width (D 2 ) and in-plane orientation angle ( ⁇ ).
  • D 1 length
  • D 2 width
  • ⁇ in-plane orientation angle
  • the metasurface can reconstruct up to seven combinations of polarization-related information.
  • the proposed metasurface can be used in a certain wavelength range. Using this property, the gray-scale image information of the three primary colors is coupled to three independent polarization channels, and the three-channel information is matched through a pre-compensation algorithm to reconstruct a full-color holographic image, as shown in Figure 2. Since the information is coupled into three independent input/output polarization combinations, the crosstalk image of other channels is naturally eliminated to achieve close to zero crosstalk between channels.
  • the pre-compensation algorithm includes chromatic aberration pre-compensation and distortion pre-compensation.
  • Chromatic aberration is the field angle or size of the image is proportional to the wavelength.
  • the target pattern needs to be scaled according to the wavelength, and the zoom factor is inversely proportional to the wavelength. . Since the pattern formed by the meta-surface has a large field of view, which results in a large spherical distortion in the far field, the target pattern needs to be corrected for the spherical distortion in the reverse direction according to the field of view to realize the far-field distortionless holographic pattern.
  • FIG 4 is a schematic diagram of a single unit of a metasurface of the present invention.
  • the metasurface is composed of sub-wavelength rectangular nanopillars of TiO2, which is a high refractive index dielectric material in the visible light range.
  • the nanopillars are arranged in square repeating units, are periodic, and contain multiple metasurface units.
  • Figure 4 shows a single metasurface unit with three independently adjustable structural parameters (D 1 , D 2 , ⁇ ) and a fixed height H.
  • the rectangular cross-section of the sub-wavelength nanopillars results in different effective refractive indexes along the two axes. Therefore, each nanopillar can be regarded as a linear birefringent unit, which can produce different phases on orthogonal linear polarizations.
  • Jones matrix can be used to describe metasurface units. Therefore, if the free choice of structural parameters can make full use of the freedom of the Jones matrix, a single unit can control the polarization and phase.
  • phase shift of x-polarized light and y-polarized light ( ⁇ x , ⁇ y ) is the key to realize the polarization multiplexing function, which covers the range of 0-2 ⁇ .
  • Normally linearly polarized light incident along the axis of the nano-cylinder will not change the polarization but will produce a phase shift.
  • Figure 5 shows the phase distribution and transmittance distribution of a single nanostructure unit of the present invention under x-polarized light.
  • the unit period of 400nm and the height of the nanopillars of 800nm were set in the simulation.
  • ⁇ y under the y polarization can be simply obtained by transposing the x polarization result as shown in FIG. 5.
  • any combination range of ⁇ x and ⁇ y in 0-2 ⁇ can be realized by appropriately selecting D 1 and D 2.
  • FIG. 6 is a scanning electron microscope image of the metasurface in Example 1.
  • Figure 6 shows a top view and an oblique view of the scanning electron microscope (SEM) image of the TiO2 holographic metasurface solution of Example 1;
  • Figure 4(b) is The simulation diagram and optical characterization result diagram of the metasurface in Example 1, as shown in Figure 7, the two off-axis images of "HUNAN” and “UNIVERSITY” are encoded on the metasurface, which proves the function of the dual-channel holographic metasurface .
  • SEM scanning electron microscope
  • FIG. 8 is a scanning electron microscope image of the metasurface in Example 2
  • FIG. 8 shows a top view and an oblique view of a scanning electron microscope (SEM) image of the TiO2 holographic metasurface solution of Example 2.
  • Figure 9 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 2. As shown in Figure 9, three off-axis images of "X", "Y” and "Z" are encoded on the metasurface, which proves three The function of the channel holographic metasurface.
  • Fig. 10 is a schematic diagram of the color holographic coding in Embodiment 3, and Fig. 10 shows the generation process of the polarized multi-channel color holographic metasurface.
  • the target color image is divided into three three color components corresponding to wavelengths of 633 nm (R), 532 nm (G), and 450 nm (B).
  • the phase distribution corresponding to the image is obtained, and then it is coupled to three independent polarization channels.
  • the layout map corresponding to the meta-surface formed by the structural parameters and orientation angles closest to the phase response is found. Then, a color image of 400 ⁇ m ⁇ 400 ⁇ m meta-surface encoding information was produced and characterized.
  • 11 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 3, that is, a color image of information encoded by the metasurface.
  • the present invention has the following advantages and effects:
  • the present invention can realize the encoding of up to three independent information and seven independent information combinations through a metasurface composed of a single structure, so that the structure is more compact and the space utilization rate is higher.
  • the structure of the superstructure surface element of the present invention is simple in composition, and the planar structure makes the processing simple and can be manufactured in large quantities.
  • the metasurface of the present invention is used within a certain wavelength range, and can be used in the ultraviolet, visible and infrared bands by selecting different materials.
  • the full-color holography realized by the invention has the advantages of high efficiency, large field of view, and near-zero crosstalk, so that the metasurface color holography is closer to the actual use scene.

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Abstract

A polarization multi-channel metasurface optical element and a method for reconstructing a full color holographic image. The polarization multi-channel metasurface optical element consists of a dielectric substrate (1) and an anisotropic dielectric nanostructure array thereon, and achieves encoding of a holographic image for up to three independent polarization channels by means of adjusting the in-plane dimensions and the in-plane angles of nanostructures at various locations; in addition, the metasurface has the characteristic of wide band usage, and high efficiency multi-channel polarization multi-channel holography can be achieved at different wavebands by means of selecting different dielectric materials. By means of coupling three primary color components of a full color picture into three independent polarization channels of a visible light waveband polarization multi-channel metasurface, full color holographic displaying with near zero crosstalk can be achieved.

Description

偏振多通道超构表面光学元件及重建全彩全息图像的方法Polarized multi-channel superstructure surface optical element and method for reconstructing full-color holographic image 技术领域Technical field
本发明涉及微纳光学及光学全息领域，特别是涉及一种偏振多通道超构表面光学元件及重建全彩全息图像的方法。The present invention relates to the field of micro-nano optics and optical holography, in particular to a polarization multi-channel superstructure surface optical element and a method for reconstructing a full-color holographic image.
背景技术Background technique
超构表面可以允许人们在二维平面进行光波的相位、幅值、偏振等任意的调控，赋予了设计新型光学元件的极大自由度。所以，近些年，基于超构表面的透镜、光线偏折器、偏振转换器、全息超构表面都被提出来并广泛研究。其中，由于大视场角、高密度、分辨率高等特点，使得基于超构表面的全息技术得到广泛关注，并基于此，发展出各种多通道超构表面全息，其中，交错单元、多平面、多角度等策略通常波长多通道应用，例如彩色全息或多波长超透镜。然而，在不利用其它空间自由度情况下难以实现超低串扰彩色全息。事实上，与传统的DOE元件相比，超构表面的特点是偏振的亚波长调节，而且，基于两个正交入射偏振态的多通道器件理论上可以完全抑制通道之间的串扰，实现双功能应用。然而，先前基于PB相位的交错单元或各向异性的结构表面尚未充分探索双折射超构表面单元的自由度，不能实现三个独立的偏振通道的全息图像的编码和高效率的多通道偏振多通道全息。Metasurfaces can allow people to adjust the phase, amplitude, and polarization of light waves arbitrarily in a two-dimensional plane, giving them great freedom in designing new optical components. Therefore, in recent years, lenses based on metasurfaces, light deflectors, polarization converters, and holographic metasurfaces have all been proposed and extensively studied. Among them, due to the characteristics of large field of view, high density, high resolution, etc., the holographic technology based on meta-surface has received widespread attention. Based on this, various multi-channel meta-surface holograms have been developed. Among them, interlaced unit, multi-plane Strategies such as multi-angle and multi-angle are usually used in wavelength multi-channel applications, such as color holography or multi-wavelength hyperlenses. However, it is difficult to achieve ultra-low crosstalk color holography without using other spatial degrees of freedom. In fact, compared with the traditional DOE element, the meta-surface is characterized by sub-wavelength adjustment of polarization. Moreover, the multi-channel device based on two orthogonal incident polarization states can theoretically completely suppress the crosstalk between channels and realize dual Functional application. However, the previous PB-phase-based interlaced units or anisotropic structural surfaces have not yet fully explored the degree of freedom of the birefringent metasurface unit, and cannot realize the encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization. Channel holography.
发明内容Summary of the invention
本发明的目的是提供一种偏振多通道超构表面光学元件及重建全彩全息图像的方法，能够实现三个独立的偏振通道的全息图像的编码和高效率的多通道偏振多通道全息。The purpose of the present invention is to provide a polarization multi-channel meta-surface optical element and a method for reconstructing a full-color holographic image, which can realize encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization multi-channel holography.
为实现上述目的，本发明提供了如下方案：In order to achieve the above objective, the present invention provides the following solutions:
一种偏振多通道超构表面光学元件，包括：介质衬底和各向异性的电介质纳米结构阵列，所述各向异性的电介质纳米结构阵列设置在所述介质衬底上，所述各向异性的电介质纳米结构阵列包含多个纳米柱。A polarized multi-channel metasurface optical element, comprising: a dielectric substrate and an anisotropic dielectric nanostructure array, the anisotropic dielectric nanostructure array is arranged on the dielectric substrate, and the anisotropic The dielectric nanostructure array contains multiple nanopillars.
可选的，所述介质衬底采用石英衬底、氧化铝衬底、玻璃衬底或金刚石衬底。Optionally, the dielectric substrate is a quartz substrate, an alumina substrate, a glass substrate or a diamond substrate.
可选的，所述纳米柱采用矩形纳米柱、椭圆形纳米柱、不对称十字形纳米柱或L形纳米柱。Optionally, the nanopillars are rectangular nanopillars, elliptical nanopillars, asymmetric cross-shaped nanopillars or L-shaped nanopillars.
可选的，所述纳米柱的结构材料采用TiO2、HfO2、ZrO2、GaN、Si2N3、Si、GaAs、ZnS或AlN。Optionally, the structural material of the nano-pillars is TiO2, HfO2, ZrO2, GaN, Si2N3, Si, GaAs, ZnS or AlN.
可选的，所述纳米柱的高度范围为200nm-1500nm，所述纳米柱在所述介质衬底表面的尺寸为20nm-1000nm，所述纳米柱在所述介质衬底表面任意设置。Optionally, the height range of the nanopillars is 200nm-1500nm, the size of the nanopillars on the surface of the dielectric substrate is 20nm-1000nm, and the nanopillars are arbitrarily arranged on the surface of the dielectric substrate.
一种基于偏振多通道超构表面元件的重建全彩全息图像的方法，包括：A method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element, including:
获取纳米柱的长轴尺寸、短轴尺寸以及纳米柱在介质衬底表面的面内角度，其中，所述长轴尺寸、所述短轴尺寸和所述面内角度在单元周期内任意调控；Obtaining the long axis size, the short axis size, and the in-plane angle of the nano column on the surface of the dielectric substrate, wherein the long axis size, the short axis size, and the in-plane angle are arbitrarily adjusted within the unit period;
通过在介质衬底上按周期排布不同所述长轴尺寸、所述短轴尺寸和所述面内角度的纳米结构单元构造位置各异的琼斯矩阵，完成三个独立面相位分布的编码，所述琼斯矩阵包含三个独立的相位信息，所述三个独立的相位信息通过三个不同的入射光和出射光的偏振组合进行独立重构；By periodically arranging the nanostructure units with different major axis sizes, minor axis sizes, and in-plane angles on the dielectric substrate to construct Jones matrices with different positions, the encoding of three independent plane phase distributions is completed, The Jones matrix includes three independent phase information, and the three independent phase information is independently reconstructed by three different polarization combinations of incident light and outgoing light;
将三原色灰度图像信息通过全息相位恢复算法计算得到相位分布，并耦合到三个独立的偏振通道中；Calculate the phase distribution of the gray image information of the three primary colors through the holographic phase recovery algorithm, and couple it to three independent polarization channels;
将所述三原色灰度图像通过预补偿算法匹配所述偏振通道中的信 息，得到全彩色全息图像。The three primary color grayscale images are matched with the information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image.
可选的，所述将所述三原色灰度图像通过预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像，具体包括：Optionally, said matching the three primary color grayscale images to information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image specifically includes:
将所述三原色灰度图像采用色差预补偿算法和畸变预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像。The three primary color grayscale images are matched with the information in the polarization channel using a color difference pre-compensation algorithm and a distortion pre-compensation algorithm to obtain a full-color holographic image.
根据本发明提供的具体实施例，本发明公开了以下技术效果：According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:
本发明提出的偏振多通道超构表面光学元件是由介质衬底和其上的各向异性的电介质纳米结构阵列组成，通过调控各个位置的纳米结构的结构参数(面内尺寸和面内角度)实现最多三个独立的偏振通道的全息图像的编码，且该超构表面具有宽带可用的性质，通过选择不同电介质的材料，可以在不同波段内(如红外波段、可见光波段及紫外波段)实现高效率的多通道偏振多通道全息。通过将全彩图片的三原色分量耦合进可见光波段偏振多通道超构表面的三个独立偏振通道，可以实现近零串扰的全彩全息显示。本发明提出的多通道偏振多通道超构表面一方面可用于偏振信息加密和数据防伪；另外，该元件为平面二维结构，结构组成简单、体积轻薄，可大批量生产；最后，该彩色全息显示技术具有超大视场角、近零串扰、超高分辨率等优点，可以广泛应用在全息投影、近眼显示等行业。The polarized multi-channel metasurface optical element proposed in the present invention is composed of a dielectric substrate and an anisotropic dielectric nanostructure array on it, and the structure parameters (in-plane size and in-plane angle) of the nanostructures at various positions are adjusted and controlled. Realize the encoding of holographic images with up to three independent polarization channels, and the meta-surface has broadband usable properties. By choosing different dielectric materials, it can achieve high resolution in different wavelength bands (such as infrared, visible and ultraviolet). Efficient multi-channel polarization multi-channel holography. By coupling the three primary color components of the full-color picture into the three independent polarization channels of the visible light waveband polarization multi-channel metasurface, a full-color holographic display with near zero crosstalk can be realized. The multi-channel polarization multi-channel metasurface proposed by the present invention can be used for polarization information encryption and data anti-counterfeiting on the one hand; in addition, the element has a planar two-dimensional structure, simple structure, lightweight and thin, and can be mass-produced; finally, the color hologram Display technology has the advantages of super large field of view, near zero crosstalk, super high resolution, etc., and can be widely used in industries such as holographic projection and near-eye display.
附图说明Description of the drawings
为了更清楚地说明本发明实施例或现有技术中的技术方案，下面将对实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本发明的一些实施例，对于本领域普通技术人员来讲，在不付出创造性劳动性的前提下，还可以根据这些附图获得其他的附图。In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following will briefly introduce the drawings needed in the embodiments. Obviously, the drawings in the following description are only some of the present invention. Embodiments, for those of ordinary skill in the art, without creative labor, other drawings can be obtained from these drawings.
图1为本发明偏振多通道超构表面光学元件组成示意图；Figure 1 is a schematic diagram of the composition of the polarized multi-channel metasurface optical element of the present invention;
图2为本发明实现偏振多通道全彩全息的超构表面的示意图；Fig. 2 is a schematic diagram of a metasurface for realizing polarization multi-channel full-color holography according to the present invention;
图3为本发明基于偏振多通道超构表面元件的重建全彩全息图像的方法流程图；Fig. 3 is a flowchart of a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element of the present invention;
图4为本发明超构表面单个单元的示意图；Figure 4 is a schematic diagram of a single unit of the metasurface of the present invention;
图5为本发明单个单元在x偏振光下的相位分布和透射率分布；Figure 5 is the phase distribution and transmittance distribution of a single unit of the present invention under x-polarized light;
图6为实施例1中超构表面的扫描电镜图；Figure 6 is a scanning electron micrograph of the metasurface in Example 1;
图7为实施例1中超构表面的仿真图和光学表征结果图；FIG. 7 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 1;
图8为实施例2中超构表面的扫描电镜图；Figure 8 is a scanning electron micrograph of the metasurface in Example 2;
图9为实施例2中超构表面的仿真图和光学表征结果图；9 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 2;
图10为实施例3中彩色全息编码示意图；Figure 10 is a schematic diagram of color holographic coding in Embodiment 3;
图11为实施例3中超构表面的仿真图和光学表征结果图。11 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 3.
具体实施方式detailed description
下面将结合本发明实施例中的附图，对本发明实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本发明一部分实施例，而不是全部的实施例。基于本发明中的实施例，本领域普通技术人员在没有做出创造性劳动前提下所获得的所有其他实施例，都属于本发明保护的范围。The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present invention.
本发明的目的是提供一种偏振多通道超构表面光学元件及重建全彩全息图像的方法，能够实现三个独立的偏振通道的全息图像的编码和高效率的多通道偏振多通道全息。The purpose of the present invention is to provide a polarization multi-channel meta-surface optical element and a method for reconstructing a full-color holographic image, which can realize encoding of holographic images with three independent polarization channels and high-efficiency multi-channel polarization multi-channel holography.
为使本发明的上述目的、特征和优点能够更加明显易懂，下面结合附图和具体实施方式对本发明作进一步详细的说明。In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments.
图1为本发明偏振多通道超构表面光学元件组成示意图。如图1所 示，一种偏振多通道超构表面光学元件包括：介质衬底1和各向异性的电介质纳米结构阵列，所述各向异性的电介质纳米结构阵列设置在所述介质衬底1上，所述各向异性的电介质纳米结构阵列包含多个纳米柱2。Figure 1 is a schematic diagram of the composition of the polarized multi-channel metasurface optical element of the present invention. As shown in FIG. 1, a polarization multi-channel metasurface optical element includes: a dielectric substrate 1 and an anisotropic dielectric nanostructure array, and the anisotropic dielectric nanostructure array is disposed on the dielectric substrate 1. Above, the anisotropic dielectric nanostructure array includes a plurality of nanopillars 2.
所述介质衬底1采用石英衬底、氧化铝衬底、玻璃衬底或金刚石衬底。The dielectric substrate 1 is a quartz substrate, an alumina substrate, a glass substrate or a diamond substrate.
所述纳米柱2采用矩形纳米柱、椭圆形纳米柱、不对称十字形纳米柱或L形纳米柱。所述纳米柱2的结构材料采用TiO2、HfO2、ZrO2、GaN、Si2N3、Si、GaAs、ZnS或AlN。所述纳米柱2的高度范围为200nm-1500nm，所述纳米柱2在所述介质衬底表面的尺寸为20nm-1000nm，所述纳米柱在所述介质衬底表面任意设置。The nano-pillars 2 adopt rectangular nano-pillars, elliptical nano-pillars, asymmetric cross-shaped nano-pillars or L-shaped nano-pillars. The structural material of the nano-pillar 2 is TiO2, HfO2, ZrO2, GaN, Si2N3, Si, GaAs, ZnS or AlN. The height range of the nanopillars 2 is 200nm-1500nm, the size of the nanopillars 2 on the surface of the dielectric substrate is 20nm-1000nm, and the nanopillars are arbitrarily arranged on the surface of the dielectric substrate.
一种全彩全息图像采集***包括：偏振多通道超构表面光学元件、光源和接收屏，所述偏振多通道超构表面光学元件包括介质衬底1和各向异性的电介质纳米结构阵列，所述光源位于所述介质衬底1一侧，所述接收屏位于所述各向异性的电介质纳米结构阵列的一侧，所述光源发出的光通过所述介质衬底1和所述各向异性的电介质纳米结构阵列到达所述接收屏形成全彩全息图。A full-color holographic image acquisition system includes: a polarization multi-channel metasurface optical element, a light source, and a receiving screen. The polarization multi-channel metasurface optical element includes a dielectric substrate 1 and an anisotropic dielectric nanostructure array. The light source is located on the side of the dielectric substrate 1, the receiving screen is located on the side of the anisotropic dielectric nanostructure array, and the light emitted by the light source passes through the dielectric substrate 1 and the anisotropic The array of dielectric nanostructures reaches the receiving screen to form a full-color hologram.
所述光源包括入射y轴偏振的蓝色光源、入射x轴偏振的绿色光源和入射x轴偏振的红色光源。所述全彩全息图包括蓝色全息分量、绿色全息分量和红色全息分量。The light source includes a blue light source with incident y-axis polarization, a green light source with incident x-axis polarization, and a red light source with incident x-axis polarization. The full-color hologram includes a blue holographic component, a green holographic component, and a red holographic component.
图2为本发明实现偏振多通道全彩全息的超构表面的示意图。其中，1为介质衬底，2为纳米柱，3为入射y轴偏振的蓝色光源，4为入射x偏振的绿色光源，5为入射x偏振的红色光源，6为单个单元，7为出射x偏振的红光，8出射y偏振的绿光，9出射y偏振的蓝光，10为全彩全息图，11为红色全息分量，12为绿色全息分量，13为蓝色全息分量。Fig. 2 is a schematic diagram of the meta-surface for realizing polarization multi-channel full-color holography according to the present invention. Among them, 1 is the dielectric substrate, 2 is the nano-pillar, 3 is the incident y-polarized blue light source, 4 is the incident x-polarized green light source, 5 is the incident x-polarized red light source, 6 is a single unit, and 7 is the exit X-polarized red light, 8 emits y-polarized green light, 9 emits y-polarized blue light, 10 is a full-color hologram, 11 is a red holographic component, 12 is a green holographic component, and 13 is a blue holographic component.
图3为本发明基于偏振多通道超构表面元件的重建全彩全息图像的 方法流程图。如图3所示，一种基于偏振多通道超构表面元件的重建全彩全息图像的方法，包括：Fig. 3 is a flowchart of a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element of the present invention. As shown in Figure 3, a method for reconstructing a full-color holographic image based on a polarization multi-channel metasurface element includes:
步骤101：获取纳米柱的长轴尺寸、短轴尺寸以及纳米柱在介质衬底表面的面内角度，其中，所述长轴尺寸、所述短轴尺寸和所述面内角度在单元周期内任意调控；Step 101: Obtain the long axis size, the short axis size, and the in-plane angle of the nano column on the surface of the dielectric substrate, wherein the long axis size, the short axis size, and the in-plane angle are within a unit period Arbitrary regulation
步骤102：通过在介质衬底上按周期排布不同所述长轴尺寸、所述短轴尺寸和所述面内角度的纳米结构单元构造位置各异的琼斯矩阵，完成三个独立面相位分布的编码，所述琼斯矩阵包含三个独立的相位信息，所述三个独立的相位信息通过三个不同的入射光和出射光的偏振组合进行独立重构；Step 102: By periodically arranging the nanostructure units with different major axis sizes, minor axis sizes and in-plane angles on the dielectric substrate to construct Jones matrices with different positions to complete three independent plane phase distributions The Jones matrix contains three independent phase information, and the three independent phase information is independently reconstructed by three different polarization combinations of incident light and outgoing light;
步骤103：将三原色灰度图像信息通过全息相位恢复算法计算得到相位分布，并耦合到三个独立的偏振通道中；Step 103: Calculate the phase distribution of the gray image information of the three primary colors through the holographic phase recovery algorithm, and couple it to three independent polarization channels;
步骤104：将所述三原色灰度图像通过预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像，具体包括：Step 104: Match the three primary color grayscale images with the information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image, which specifically includes:
将所述三原色灰度图像采用色差预补偿算法和畸变预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像。The three primary color grayscale images are matched with the information in the polarization channel using a color difference pre-compensation algorithm and a distortion pre-compensation algorithm to obtain a full-color holographic image.
将一个纳米柱看成一个纳米结构，将每个纳米结构看成一线性双折射单元，双折射单元可以通过控制长轴和短轴的相位调控和面内旋转角度，构造一个任意的对称琼斯矩阵，从而实现单个纳米结构对偏振和相位的任意调控，且矩阵中含有三个不同相位，并可以通过不同入射和出射的偏振组合来独立地重构。而单个各向异性的亚波长纳米结构可以看作一个双折射单元，通过任意选择长轴和短轴的尺寸以及面内旋转角度即可构造任意的琼斯矩阵，所以可以实现多达三个独立相位的编码，并通过入射和出射偏振的组合可以实现三个独立相位的重构。进一步在不同位置构造不同尺寸的纳米结构以实现设计相位分布，则可以构造实现 三个独立信息的编码的超构表面元件。利用此特点，将不同全息图加密到超构表面对应通道上，则可实现偏振多通道可切换全息加密。另外，该元件在一定波长范围内使用。将彩色图像三原色分量耦合到三个独立偏振通道，通过波长、入射/出射偏振组合即可实现全彩全息显示。Think of a nanopillar as a nanostructure, and each nanostructure as a linear birefringent unit. The birefringent unit can construct an arbitrary symmetric Jones matrix by controlling the phase adjustment of the long axis and the short axis and the in-plane rotation angle. In this way, a single nanostructure can control the polarization and phase arbitrarily, and the matrix contains three different phases, which can be independently reconstructed through different incident and exit polarization combinations. A single anisotropic sub-wavelength nanostructure can be regarded as a birefringent unit. Any Jones matrix can be constructed by arbitrarily selecting the size of the major axis and the minor axis and the in-plane rotation angle, so up to three independent phases can be achieved The encoding of three independent phases can be achieved through the combination of incident and outgoing polarization. Furthermore, by constructing nanostructures of different sizes at different positions to realize the design phase distribution, it is possible to construct a metasurface element that realizes the encoding of three independent information. Using this feature, by encrypting different holograms to the corresponding channels of the metasurface, polarization multi-channel switchable holographic encryption can be realized. In addition, the element is used within a certain wavelength range. The three primary color components of a color image are coupled to three independent polarization channels, and a full-color holographic display can be realized through the combination of wavelength and incident/outgoing polarization.
参数选择：Preferences:
通过三个独立相位，求解由琼斯矩阵构建的相位与结构参数关系的方程组，得到三个结构参数。Through three independent phases, the equations of the relationship between phase and structural parameters constructed by Jones matrix are solved to obtain three structural parameters.
推导过程如下：The derivation process is as follows:
将每个纳米结构看成线性双折射单元，则每个单元可用琼斯矩阵进行表达Regarding each nanostructure as a linear birefringent unit, each unit can be expressed by Jones matrix
Figure PCTCN2020105245-appb-000001
Figure PCTCN2020105245-appb-000001
其中，φ x和φ y是两个轴的相位延迟，由结构尺寸D 1，D 2分别决定；R由面内角θ表达，R为旋转矩阵。 Among them, φ x and φ y are the phase delays of the two axes, which are determined by the structural dimensions D 1 and D 2 respectively; R is expressed by the in-plane angle θ, and R is the rotation matrix.
Figure PCTCN2020105245-appb-000002
Figure PCTCN2020105245-appb-000002
入射和出射电场关系可以表达为E 0＝JE i。因此琼斯矩阵可以通过两个轴相位延迟和面内角进行表达： The relationship between the incident and exit electric fields can be expressed as E 0 =JE i . Therefore, the Jones matrix can be expressed by two-axis phase delay and in-plane angle:
Figure PCTCN2020105245-appb-000003
Figure PCTCN2020105245-appb-000003
则可以简化为Can be simplified to
Figure PCTCN2020105245-appb-000004
Figure PCTCN2020105245-appb-000004
其中三个独立相位φ 1，φ 2，φ 3可以通过求解方程组(3)得到φ x，φ y，θ，则可得到对应的D 1，D 2，θ三个结构参数。 Among them, the three independent phases φ 1 , φ 2 , and φ 3 can be obtained by solving equation (3) to obtain φ x , φ y , θ, and then the corresponding three structural parameters D 1 , D 2, θ can be obtained.
由于提出的超构表面可以编码三个独立相位信息，所以通过三个独立信息进行组合，即可得到
Figure PCTCN2020105245-appb-000005
种不同的信息组合。 Since the proposed metasurface can encode three independent phase information, the three independent information can be combined to obtain
Figure PCTCN2020105245-appb-000005
Different combinations of information.
图2显示了实现偏振多通道全彩全息的超构表面的示意图。首先通过考虑琼斯矩阵的不同灵活性来探索不同数量的偏振通道的全息超构表面。通过具有三个独立结构参数的TiO2矩形纳米柱阵列实现表面：长度(D 1)、宽度(D 2)和面内取向角(θ)。通过固定取向角而控制长度和宽度，可以将两个独立的相位编码带到单个纳米柱并通过两个正交入射偏振态进行重构。因此，可以用不同的偏振输入切换两个独立的远场全息图像。此外，为了进一步考虑取向角并充分利用纳米柱的参数自由度，还可以利用输入和输出偏振态的不同组合来实现三个独立信息。结果，超构表面可以重建多达七个与偏振相关的信息组合。此外，值得注意的是，所提出的超构表面可在一定的波长范围内使用。利用此性质，将三原色的灰度图像信息耦合到三个独立的偏振通道中，并通过预补偿算法匹配三通道信息，重建全彩色全息图像，如图2显示。由于信息被耦合到三个独立的输入/输出偏振组合中，因此自然地消除了其他信道的串扰图像以实现信道之间接近零的串扰。 Figure 2 shows a schematic diagram of a metasurface for realizing polarization multi-channel full-color holography. First, by considering the different flexibility of Jones matrix to explore the holographic metasurface with different numbers of polarization channels. The surface is realized by a TiO2 rectangular nanopillar array with three independent structural parameters: length (D 1 ), width (D 2 ) and in-plane orientation angle (θ). By fixing the orientation angle and controlling the length and width, two independent phase encodings can be brought to a single nanopillar and reconstructed by two orthogonal incident polarization states. Therefore, two independent far-field holographic images can be switched with different polarization inputs. In addition, in order to further consider the orientation angle and make full use of the parameter freedom of the nanopillars, different combinations of input and output polarization states can also be used to achieve three independent information. As a result, the metasurface can reconstruct up to seven combinations of polarization-related information. In addition, it is worth noting that the proposed metasurface can be used in a certain wavelength range. Using this property, the gray-scale image information of the three primary colors is coupled to three independent polarization channels, and the three-channel information is matched through a pre-compensation algorithm to reconstruct a full-color holographic image, as shown in Figure 2. Since the information is coupled into three independent input/output polarization combinations, the crosstalk image of other channels is naturally eliminated to achieve close to zero crosstalk between channels.
预补偿算法包括色差预补偿和畸变预补偿，色差是图像的视场角或大小与波长呈正比，为了使得三个颜色分量大小一致，需对目标图案根据波长进行缩放，缩放倍数与波长呈反比。由于超构表面形成的图案视场角很大，导致远场很大的球面畸变，所以需对目标图案根据视场角大 小进行反向的球面畸变校正，以实现远场无畸变全息图案。The pre-compensation algorithm includes chromatic aberration pre-compensation and distortion pre-compensation. Chromatic aberration is the field angle or size of the image is proportional to the wavelength. In order to make the three color components the same size, the target pattern needs to be scaled according to the wavelength, and the zoom factor is inversely proportional to the wavelength. . Since the pattern formed by the meta-surface has a large field of view, which results in a large spherical distortion in the far field, the target pattern needs to be corrected for the spherical distortion in the reverse direction according to the field of view to realize the far-field distortionless holographic pattern.
图4为本发明超构表面单个单元的示意图。超构表面由TiO2的亚波长矩形纳米柱构成，TiO2是可见光范围内的高折射率电介质材料。纳米柱以方形重复单元排列，具有周期性，包含多个超构表面单元。如图4示出了具有三个独立可调结构参数(D 1，D 2，θ)和固定高度H的单个超构表面单元。亚波长纳米柱的矩形横截面导致沿着两个轴具有不同的有效折射率，因此，每个纳米柱可以看作线性双折射单元，其可以在正交线性偏振上产生不同的相位。如果无振幅调控，则可以使用琼斯矩阵来描述超构表面单元。因此，如果自由选择结构参数可以充分利用琼斯矩阵的自由度，则单个单元可以完成控制极化和相位。 Figure 4 is a schematic diagram of a single unit of a metasurface of the present invention. The metasurface is composed of sub-wavelength rectangular nanopillars of TiO2, which is a high refractive index dielectric material in the visible light range. The nanopillars are arranged in square repeating units, are periodic, and contain multiple metasurface units. Figure 4 shows a single metasurface unit with three independently adjustable structural parameters (D 1 , D 2 , θ) and a fixed height H. The rectangular cross-section of the sub-wavelength nanopillars results in different effective refractive indexes along the two axes. Therefore, each nanopillar can be regarded as a linear birefringent unit, which can produce different phases on orthogonal linear polarizations. If there is no amplitude control, Jones matrix can be used to describe metasurface units. Therefore, if the free choice of structural parameters can make full use of the freedom of the Jones matrix, a single unit can control the polarization and phase.
x偏振光和y偏振光(φ x，φ y)的相移是实现偏振复用功能的关键，其覆盖0-2π范围。沿纳米柱轴线入射的正常线性偏振光不会改变偏振但会产生相移。这意味着相移可以表示为纳米柱D 1和D 2的大小的函数。因此，通过有限差分时域法在532nm波长下模拟在x偏振下没有旋转(θ＝0)的纳米柱的相移φ x，如图5所示。图5为本发明单个纳米结构单元在x偏振光下的相位分布和透射率分布。在模拟中设定400nm的单位周期和800nm的纳米柱的高度。另外，由于对称性，可以通过如图5所示的x偏振结果的转置简单地获得y偏振下的φ y。利用这样的数据库，可以通过适当地选择D 1和D 2来实现0-2π中任何φ x和φ y组合范围。 The phase shift of x-polarized light and y-polarized light (φ x , φ y ) is the key to realize the polarization multiplexing function, which covers the range of 0-2π. Normally linearly polarized light incident along the axis of the nano-cylinder will not change the polarization but will produce a phase shift. This means that the phase shift can be expressed as a function of the size of the nanopillars D 1 and D 2. Therefore, the phase shift φ x of the nano-pillar without rotation (θ=0) under the x polarization is simulated at a wavelength of 532 nm by the finite difference time domain method, as shown in FIG. 5. Figure 5 shows the phase distribution and transmittance distribution of a single nanostructure unit of the present invention under x-polarized light. The unit period of 400nm and the height of the nanopillars of 800nm were set in the simulation. In addition, due to the symmetry, φ y under the y polarization can be simply obtained by transposing the x polarization result as shown in FIG. 5. Using such a database, any combination range of φ x and φ y in 0-2π can be realized by appropriately selecting D 1 and D 2.
实施例1：Example 1:
考虑偏振相关多路复用表面的两种方案。首先，如果超构表面单元没有旋转，输出电场可以分别在x和y偏振光下得到。因此，两个独立的相位轮廓可以被编码成单个超构表面并且通过两个正交入射偏振来切换。图6为实施例1中超构表面的扫描电镜图，图6中示出了实施例1的TiO2全息超构表面方案的扫描电子显微镜(SEM)图的俯视图和斜 视图；图4(b)是实施例1中超构表面的仿真图和光学表征结果图，如图7所示，“HUNAN”和“UNIVERSITY”的两个离轴图像被编码在超构表面，证明双通道全息超构表面的功能。Consider two schemes of polarization dependent multiplexing surface. First, if the metasurface unit is not rotated, the output electric field can be obtained under x and y polarized light, respectively. Therefore, two independent phase profiles can be encoded into a single metasurface and switched by two orthogonal incident polarizations. Figure 6 is a scanning electron microscope image of the metasurface in Example 1. Figure 6 shows a top view and an oblique view of the scanning electron microscope (SEM) image of the TiO2 holographic metasurface solution of Example 1; Figure 4(b) is The simulation diagram and optical characterization result diagram of the metasurface in Example 1, as shown in Figure 7, the two off-axis images of "HUNAN" and "UNIVERSITY" are encoded on the metasurface, which proves the function of the dual-channel holographic metasurface .
实施例2：Example 2:
为了充分利用琼斯矩阵的灵活性，通过自由选择纳米柱的三个参数，包括旋转角度。那么输出电场可以包括φ 1，φ 2和φ 3的信息。在x和y偏振光下，相位φ 1，φ 2和φ 3是φ x，φ y和θ的函数。图8为实施例2中超构表面的扫描电镜图，图8示出了实施例2的TiO2全息超构表面方案的扫描电子显微镜(SEM)图的俯视图和斜视图。图9为实施例2中超构表面的仿真图和光学表征结果图，如图9所示，“X”、“Y”和“Z”的三个离轴图像被编码在超构表面，证明三通道全息超构表面的功能。 In order to make full use of the flexibility of the Jones matrix, three parameters of the nanopillars are freely selected, including the rotation angle. Then the output electric field can include φ 1 , φ 2 and φ 3 information. Under x and y polarized light, the phases φ 1 , φ 2 and φ 3 are functions of φ x , φ y and θ. FIG. 8 is a scanning electron microscope image of the metasurface in Example 2, and FIG. 8 shows a top view and an oblique view of a scanning electron microscope (SEM) image of the TiO2 holographic metasurface solution of Example 2. Figure 9 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 2. As shown in Figure 9, three off-axis images of "X", "Y" and "Z" are encoded on the metasurface, which proves three The function of the channel holographic metasurface.
实施例3：Example 3:
由于所提出的超构表面可以支持三个独立的偏振相关信息，并且可以在一定波长范围内使用，所以可以结合三原色原理来实现偏振多通道全彩全息。图10为实施例3中彩色全息编码示意图，图10示出了偏振多通道彩色全息超构表面生成过程。首先，将目标彩色图像分成对应于波长633nm(R)，532nm(G)和450nm(B)的三个三色分量。之后，得到图像对应的相位分布，然后将其耦合到三个独立的偏振信道中。基于相位分布，找到对应具有最接近相位响应的结构参数和取向角形成的超构表面的布局图。然后制作并表征了400μm×400μm的超构表面编码的信息的彩色图像。图11为实施例3中超构表面的仿真图和光学表征结果图，即超构表面编码的信息的彩色图像。Since the proposed metasurface can support three independent polarization-related information and can be used within a certain wavelength range, the principle of three primary colors can be combined to realize polarization multi-channel full-color holography. Fig. 10 is a schematic diagram of the color holographic coding in Embodiment 3, and Fig. 10 shows the generation process of the polarized multi-channel color holographic metasurface. First, the target color image is divided into three three color components corresponding to wavelengths of 633 nm (R), 532 nm (G), and 450 nm (B). After that, the phase distribution corresponding to the image is obtained, and then it is coupled to three independent polarization channels. Based on the phase distribution, the layout map corresponding to the meta-surface formed by the structural parameters and orientation angles closest to the phase response is found. Then, a color image of 400μm×400μm meta-surface encoding information was produced and characterized. 11 is a simulation diagram and an optical characterization result diagram of the metasurface in Example 3, that is, a color image of information encoded by the metasurface.
本发明相对于现有技术具有如下的优点及效果：Compared with the prior art, the present invention has the following advantages and effects:
1.本发明可以通过单个结构组成的超构表面实现多达三个独立信息和七个独立信息组合的编码，使得结构更加紧凑，空间利用率更高。1. The present invention can realize the encoding of up to three independent information and seven independent information combinations through a metasurface composed of a single structure, so that the structure is more compact and the space utilization rate is higher.
2.本发明的超构表面元件结构组成简单，平面结构使得加工简单，可大批量制造。2. The structure of the superstructure surface element of the present invention is simple in composition, and the planar structure makes the processing simple and can be manufactured in large quantities.
3.本发明的超构表面在一定波长范围内使用，通过选择不同的材料，可以在紫外波段、可见光波段和红外波段使用。3. The metasurface of the present invention is used within a certain wavelength range, and can be used in the ultraviolet, visible and infrared bands by selecting different materials.
本发明实现的全彩全息具有高效率、大视场角、近零串扰的优点，使得超构表面彩色全息更加接近实际使用场景。The full-color holography realized by the invention has the advantages of high efficiency, large field of view, and near-zero crosstalk, so that the metasurface color holography is closer to the actual use scene.
4.本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。4. The various embodiments in this specification are described in a progressive manner. Each embodiment focuses on the differences from other embodiments, and the same or similar parts between the various embodiments can be referred to each other.
本文中应用了具体个例对本发明的原理及实施方式进行了阐述，以上实施例的说明只是用于帮助理解本发明的装置及其核心思想；同时，对于本领域的一般技术人员，依据本发明的思想，在具体实施方式及应用范围上均会有改变之处。综上所述，本说明书内容不应理解为对本发明的限制。Specific examples are used in this article to illustrate the principles and implementation of the present invention. The descriptions of the above examples are only used to help understand the device and its core ideas of the present invention; at the same time, for those of ordinary skill in the art, according to the present invention There will be changes in the specific implementation and scope of application. In summary, the content of this specification should not be construed as limiting the present invention.

Claims (7)

  1. 一种偏振多通道超构表面光学元件，其特征在于，包括：介质衬底和各向异性的电介质纳米结构阵列，所述各向异性的电介质纳米结构阵列设置在所述介质衬底上，所述各向异性的电介质纳米结构阵列包含多个纳米柱。A polarized multi-channel metasurface optical element, which is characterized by comprising: a dielectric substrate and an anisotropic dielectric nanostructure array, the anisotropic dielectric nanostructure array is arranged on the dielectric substrate, and The anisotropic dielectric nanostructure array includes a plurality of nanopillars.
  2. 根据权利要求1所述的偏振多通道超构表面光学元件，其特征在于，所述介质衬底采用石英衬底、氧化铝衬底、玻璃衬底或金刚石衬底。The polarization multi-channel metasurface optical element according to claim 1, wherein the dielectric substrate is a quartz substrate, an alumina substrate, a glass substrate or a diamond substrate.
  3. 根据权利要求1所述的偏振多通道超构表面光学元件，其特征在于，所述纳米柱采用矩形纳米柱、椭圆形纳米柱、不对称十字形纳米柱或L形纳米柱。The polarization multi-channel metasurface optical element according to claim 1, wherein the nano-pillars are rectangular nano-pillars, elliptical nano-pillars, asymmetric cross-shaped nano-pillars or L-shaped nano-pillars.
  4. 根据权利要求3所述的偏振多通道超构表面光学元件，其特征在于，所述纳米柱的结构材料采用TiO2、HfO2、ZrO2、GaN、Si2N3、Si、GaAs、ZnS或AlN。The polarization multi-channel metasurface optical element according to claim 3, wherein the structural material of the nano-pillars is TiO2, HfO2, ZrO2, GaN, Si2N3, Si, GaAs, ZnS or AlN.
  5. 根据权利要求2所述的偏振多通道超构表面光学元件，其特征在于，所述纳米柱的高度范围为200nm-1500nm，所述纳米柱在所述介质衬底表面的尺寸为20nm-1000nm，所述纳米柱在所述介质衬底表面任意设置。The polarization multi-channel metasurface optical element according to claim 2, wherein the height range of the nano-pillars is 200 nm-1500 nm, and the size of the nano-pillars on the surface of the dielectric substrate is 20 nm-1000 nm, The nano-pillars are arbitrarily arranged on the surface of the dielectric substrate.
  6. 一种基于权利要求1-5任意一项所述的偏振多通道超构表面元件的重建全彩全息图像的方法，其特征在于，包括：A method for reconstructing a full-color holographic image based on the polarization multi-channel metasurface element according to any one of claims 1-5, characterized in that it comprises:
    获取纳米柱的长轴尺寸、短轴尺寸以及纳米柱在介质衬底表面的面内角度，其中，所述长轴尺寸、所述短轴尺寸和所述面内角度在单元周期内任意调控；Obtaining the long axis size, the short axis size, and the in-plane angle of the nano column on the surface of the dielectric substrate, wherein the long axis size, the short axis size, and the in-plane angle are arbitrarily adjusted within the unit period;
    通过在介质衬底上按周期排布不同所述长轴尺寸、所述短轴尺寸和 所述面内角度的纳米结构单元构造位置各异的琼斯矩阵，完成三个独立面相位分布的编码，所述琼斯矩阵包含三个独立的相位信息，所述三个独立的相位信息通过三个不同的入射光和出射光的偏振组合进行独立重构；By periodically arranging the nanostructure units with different major axis sizes, minor axis sizes, and in-plane angles on the dielectric substrate to construct Jones matrices with different positions, the encoding of three independent plane phase distributions is completed, The Jones matrix includes three independent phase information, and the three independent phase information is independently reconstructed by three different polarization combinations of incident light and outgoing light;
    将三原色灰度图像信息通过全息相位恢复算法计算得到相位分布，并耦合到三个独立的偏振通道中；Calculate the phase distribution of the gray image information of the three primary colors through the holographic phase recovery algorithm, and couple it to three independent polarization channels;
    将所述三原色灰度图像通过预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像。The three primary color grayscale images are matched with the information in the polarization channel through a pre-compensation algorithm to obtain a full-color holographic image.
  7. 根据权利要求6所述的采用偏振多通道超构表面元件的重建全彩全息图像的方法，其特征在于，所述将所述三原色灰度图像通过预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像，具体包括：The method for reconstructing a full-color holographic image using a polarization multi-channel metasurface element according to claim 6, wherein said matching the three-primary color grayscale image to the information in the polarization channel through a pre-compensation algorithm, Obtain a full-color holographic image, including:
    将所述三原色灰度图像采用色差预补偿算法和畸变预补偿算法匹配所述偏振通道中的信息，得到全彩色全息图像。The three primary color grayscale images are matched with the information in the polarization channel using a color difference pre-compensation algorithm and a distortion pre-compensation algorithm to obtain a full-color holographic image.
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