Multifunctional super-surface structure based on polarization, super-surface element and encryption method

Abstract

The invention discloses a multifunctional super-surface structure based on polarization, a super-surface element and an encryption method, wherein the multifunctional super-surface structure comprisesa transparent substrate and a metal nano-brick array; the metal nano-brick array comprises a plurality of nano-bricks distributed on the substrate in an array mode; the surface of each nano-brick, away from the substrate, is a working surface; the substrate is divided into a plurality of square substrate units by the nano-bricks; the nano-bricks and the corresponding substrate units form nano-brick units; the geometric parameters of the nano-brick units comprise the lengths and widths of the nano-bricks and the side lengths of the substrate units; and the geometric parameters of the nano-brick units are configured as follows: when two first linearly polarized beams with polarization directions perpendicular to each other are incident on the working surface in a perpendicular mode, the reflection rate of one of the first linearly polarized beams is the highest, the transmissivity of the other first linearly polarized beam is the highest. The structure can simultaneously and independently control the phase of transmitted light and the light intensity of reflected light.

Description

technical field [0001] The invention relates to the field of micro-nano optics technology, in particular to a polarization-based multifunctional metasurface structure, a metasurface element and an encryption method. Background technique [0002] As an ultra-thin subwavelength structure, metasurfaces can be designed as planar optical devices to achieve many functions, and the functions of metasurfaces can be further improved by embedding more control methods. This capability of metasurfaces offers clear advantages over conventional diffractive optical elements. For example, metasurface holograms that can be designed to produce different images by changing the incident polarization or wavelength. [0003] Since metallic nanoantennas can generate second harmonics, nonlinear metasurfaces can generate different images or different states of orbital angular momentum. Therefore, the existing research direction is mainly to integrate a variety of metasurfaces with different functi...

AI Technical Summary

Problems solved by technology

The main technical difficulty is that although the use of nano-brick structures with half-wave plate functions can realize geometric phase metasurface holography (Zheng G, Mühlenbernd H, Kenney M, LiG, Zentgraf T, & Zhang S. Metasurface holograms reaching 80% efficiency [J].NatureNanotechnology,2015,10(4):308-312.) and high-resolution nanoprinting (Yue F, Zhang C, Zang X F, Wen D, Gerardot B D, Zhang S, & Chen X. High-resolution grayscale image hidden ina laser beam[J].Light:Science&Applications,2018,7(1):17129.), but both need to design the steering angle of the nano-brick, the value of the steering angle of the nano-brick in the design results of the two There are often differences. However, once the design is completed, the steering angle of the nano-bricks designed by the two has only a unique value. It is the difference between these two values. Requirements for nano-printing on the value of steering angle

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