A multi-channel nanoimprint and holographic display multiplexing type metasurface based on malus law and orbital angular momentum

Abstract

This invention proposes a multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum. Its structure comprises a silica substrate and a titanium dioxide nanopillar dielectric layer, incorporating a control mechanism for both transport phase and geometric phase. In the near field, the metasurface possesses two linearly polarized dual channels, capable of displaying different images depending on the polarization direction of the incident light. In the far field, it has two OAM holographic channels of different orders, displaying different dot matrix images when OAM vortex light of different orders is incident, thus providing a protective OAM holographic image. The metasurface exhibits high nanopillar utilization, a simple structure, and ease of fabrication, enabling parallel nanoimprint and holographic display using a single nanopillar. This invention significantly advances the application of metasurfaces in information storage, optical encryption, and optical displays, while also providing new possibilities for combining metasurfaces with data encryption.

Description

Technical Field

[0001] This invention relates to multi-channel nanoprinting technology based on orbital angular momentum and reusable metasurfaces for holographic display, belonging to the field of novel artificial electromagnetic materials and optical devices. Background Technology

[0002] Orbital angular momentum (OAM), as a core inherent property of the optical field, exhibits orthogonality in OAM modes with different topological charges. This allows for the simultaneous loading, transmission, and processing of multiple information streams, fundamentally enhancing the ability to manipulate and encode information from the optical field. The infinitely controllable degrees of freedom inherent in OAM optical field manipulation technology provide a new dimension and solution for the development of multi-channel information multiplexing technology, demonstrating irreplaceable application potential in cutting-edge fields such as high-capacity optical communication, multi-channel displays, and precision optical measurement.

[0003] A metasurface is a two-dimensional metamaterial with a specific nanostructure, designed artificially. It enables precise manipulation of electromagnetic waves, achieving optical properties that are difficult to attain with conventional materials. Composed of nanoscale optical scatterers, metasurfaces provide a powerful tool for manipulating the amplitude, phase, and polarization of light at subwavelength scales, unlocking unprecedented opportunities in highly integrated planar optics and miniaturization, such as metalenses, metaholograms, and reconfigurable optics.

[0004] Current metasurface research has achieved relatively mature advancements in nanoimprinting technology and OAM (Optical Angle Modulation) light field manipulation. However, the proposed metasurfaces struggle to efficiently integrate nanoimprinting and OAM light field manipulation, limiting their information capacity and functionality. This invention addresses these issues by proposing a multi-channel nanoimprinting and holographic display reusable metasurface based on Malus's law and orbital angular momentum. By cleverly utilizing Malus's law and geometric phase, and unlike partitioned arrangements, it achieves simultaneous nanoimprinting and OAM holographic functionality on a single nanopillar. This invention significantly advances the application of metasurfaces in information storage, optical encryption, and optical displays, while also providing new possibilities for combining metasurfaces with data encryption. Summary of the Invention

[0005] The purpose of this invention is to design a multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum, to solve the problems of current optical devices such as single function, small information capacity and limited channels.

[0006] The technical solution adopted by this invention to solve its technical problem is:

[0007] The metasurface comprises a silicon dioxide substrate and a titanium dioxide nanopillar dielectric layer. The arrangement of the nanopillars employs a strategy of first satisfying nanoimprinting and then OAM holographic phase requirements. For the two images to be displayed in the near-field channel, pixel combination is first performed to obtain the orientation angle range of each corresponding nanopillar.

[0008] Furthermore, the metasurface is composed of eight nanopillars with different geometric parameters, covering the transmission phase from 0 to 2π. The geometric phase coverage from 0 to 2π can be achieved by adjusting the orientation angle of the nanopillars, thereby realizing the metasurface geometric phase control mechanism.

[0009] Furthermore, the metasurface is numerically calculated to have eight elliptical nanopillars with a period of P=350nm and a height of h=900nm, and specific dimensional parameters of A1 (a=140nm, b=55nm), A2 (a=160nm, b=40nm), A3 (a=70nm, b=150nm), and A4 (a=65nm, b=135nm).

[0010] Furthermore, the incident wavelength of the metasurface is a wide visible light band λ = 532 nm, the incident light required for nanoimprinting is linearly polarized light, and the incident light required for OAM holography is circularly polarized light; Attached Figure Description

[0011] Figure 1 Schematic diagram of a multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum

[0012] Figure 2 Schematic diagram of a multi-channel nanoimprint and holographic display reusable metasurface structure unit based on Malus's law and orbital angular momentum

[0013] Figure 3 The curves show the changes in transmittance of linearly polarized light at -45˚ and -22.5˚ incident on the designed structural unit as a function of the structural orientation angle.

[0014] Figure 4 It is the curve showing the change between the geometric phase and the orientation angle of the designed structural unit.

[0015] Figure 5 The transmission phase and transmittance of the four designed metasurface unit structures with different size parameters are...

[0016] Figure 6 This is a schematic diagram of the unit structure arrangement of a multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum.

[0017] Figure 7Multi-channel nanoimprinting and holographic display of metasurface effects based on Malus's law and orbital angular momentum. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, further explanation will be provided below in conjunction with the accompanying drawings.

[0019] like Figure 1 The invention, based on Malus's law and orbital angular momentum, utilizes a multi-channel nanoimprint and holographic display reusable metasurface. When the incident light is linearly polarized at -45˚, a bear pattern can be clearly observed after placing a filter with a polarization direction of 45˚ at the exit light. When the incident light is adjusted to -22.5˚ and the filter angle is adjusted to 67.5˚, the letter combination "GUET" can be clearly seen. Furthermore, when the incident light is adjusted to left-handed circularly polarized light and a vortex phase with an OAM order of -1 is superimposed, the exit light, after passing through a quarter-wave plate, will present a heart pattern composed of bright spots. When the incident light is changed to right-handed circularly polarized light and a vortex phase with an OAM order of 1 is superimposed, a pattern of a cat wearing a hat composed of bright spots can be presented after passing through a quarter-wave plate.

[0020] accomplish Figure 1 The metasurface structural units demonstrating the functions, such as Figure 2 As shown, its structure includes a silicon dioxide substrate and a titanium dioxide nanopillar dielectric layer. The nanopillars have a period of P=350nm and a height of h=900nm, with specific dimensional parameters of A1 (a=140nm, b=55nm), A2 (a=160nm, b=40nm), A3 (a=70nm, b=150nm), and A4 (a=65nm, b=135nm).

[0021] Figure 3 The curves show the changes in transmittance of linearly polarized light at 45˚ and 67.5˚ angles with respect to the orientation angle of the structure when -45˚ and -22.5˚ linearly polarized light are incident on the designed structural unit. By changing the orientation angle of the structural unit, the transmittance of linearly polarized light orthogonal to the polarization direction of the incident light will change accordingly, conforming to Malus's law formula I=I0cos2θ. The display of nanoimprint images can be achieved by adjusting the orientation angle.

[0022] Figure 4 This curve represents the change in geometric phase and orientation angle of the designed structural unit. As the orientation angle changes, the phase of the unit structure changes accordingly, conforming to the geometric phase variation law, i.e., ∆φ=2σθ. This allows for phase control via the metasurface.

[0023] Figure 5These are the transmission phase and transmittance of four different dimensional parameters that make up the metasurface. It is particularly important to note that, to simplify the design process, this invention incorporates geometric phase; after designing four different structural units, they are rotated by 90˚ to achieve phase coverage from 0 to 2π.

[0024] Figure 6 This is a schematic diagram illustrating the strategy process of multi-channel nanoimprinting and holographic display reusable metasurfaces based on Malus's law and orbital angular momentum, involving nanoimprinting and OAM phase superposition. (Example) Figure 6 As shown in Figure a, the processing logic of the nanoimprint dual-channel image is as follows: For the two-channel image, white pixels are set to code 1 and black pixels to code 0. When both images have white pixels (combination 11), the orientation angle range is [(-85.0, -70.0), (5.0, 20.0)]. When image1 is white and image2 is black (combination 10), the orientation angle range is [(-22.5, -2.5), (72.5, 85.0)]. When the combination is 01, the orientation angle range is [(-61.0, -48), (30.0, 42.5)]. When the combination is 00, the orientation angle range is [(-50.0, -33.75), (40.0, 60.0)]. The purpose of this step is to confirm the orientation angle range at the corresponding positions, preparing for subsequent combination with geometric phase. Figure b illustrates the OAM holographic processing flow, showing samples 1 and 2. First, Dirac comb sampling is performed on the images of both channels. This step ensures the final displayed OAM image presents a clear dot matrix pattern. Then, the Gerchberg-Saxton (GS) algorithm is applied to the sampled images to obtain the initial target phase, and OAM phases of different orders are superimposed to obtain the final phase of the OAM holographic dual channels. It is important to note that during the final unit structure arrangement, since the orientation angle of the nanopillars is determined by both the orientation angle range of the nanoimprint and the rotation angle of the geometric phase, when arranging the unit structure at each position, if the corresponding orientation angle θ is within the orientation angle range, rotation is performed according to the corresponding θ; otherwise, the closest angle is selected as the orientation angle to minimize interference with the OAM holography.

[0025] Figure 7 This is a display image of a multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum. Figure 7Two samples were displayed. For sample 1, channels one and two showed a bear pattern and the letter combination GUET, respectively, as nanoimprint images; channels three and four showed a heart pattern and a kitten pattern, respectively, as OAM holographic images. Specifically, when the incident light was linearly polarized at -45˚, a bear pattern could be clearly observed after placing a filter with a polarization direction of 45˚ at the output light. When the incident light was adjusted to -22.5˚ and the filter angle was adjusted to 67.5˚, the letter combination GUET could be clearly seen. Furthermore, when the incident light was adjusted to left-hand circularly polarized light and a vortex phase with an OAM order of -1 was superimposed, the output light, after passing through a quarter-wave plate, showed a heart pattern composed of bright spots; when the incident light was changed to right-hand circularly polarized light and a vortex phase with an OAM order of 1 was superimposed, a kitten wearing a hat pattern composed of bright spots could be seen after passing through a quarter-wave plate. Similarly, for Sample 2, channels one and two display a shop and the letter combination "Cestlavie," respectively, while channels three and four display a closed and an open umbrella, respectively. For channels one and two, when the incident light is linearly polarized at -45˚, placing a filter with a polarization direction of 45˚ at the outgoing light source clearly reveals the shop pattern; when the incident light is adjusted to -22.5˚ and the filter angle is adjusted to 67.5˚, the letter combination "Cestlavie" becomes clearly visible. For channels three and four, when the incident light is adjusted to left-handed circularly polarized light and a vortex phase with an OAM order of -2 is superimposed, a closed umbrella pattern composed of bright spots is displayed; when the incident light is changed to right-handed circularly polarized light and a vortex phase with an OAM order of 3 is superimposed, an open umbrella pattern composed of bright spots is displayed.

Claims

1. A multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum, comprising a silica substrate and a titanium dioxide nanopillar dielectric layer, incorporating transport phase and geometric phase modulation mechanisms. The nanopillars are arranged on the substrate surface according to a lattice period P to control the intensity and phase required for displaying nanoprinted and holographic patterns. An xoy coordinate system is established parallel to the substrate layer, where the period refers to the distance between the geometric centers of two adjacent rectangular nanopillars on the x and y axes.

2. The multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum according to claim 1, characterized in that: The design strategy of combining Malus's law with geometric phase is used to plan and arrange metasurface nanopillars, and combined with the transport phase, so that the nanopillars can simultaneously meet the conditions of nanoimprinting and holographic display.

3. The multi-channel nanoimprint and holographic display reusable metasurface based on Malus's law and orbital angular momentum according to claim 1, characterized in that: The metasurface consists of eight nanopillars covering the 0 to 2π transport phase. Each nanopillar can achieve geometric phase modulation of 0 to 2π by adjusting the orientation angle and satisfies Malus's law, thus realizing the modulation mechanism of the metasurface's geometric phase and intensity.

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