Research On The Polarization Manipulation Of Electromagnetic Wave Based On Metasurface

For light,due to its basic physical properties,it can be used as a carrier of information.Not only that,people can also perceive spatial structure through the direction of light propagation.For example,holographic display is a three-dimensional display that depends on the spatial phase information of light.Polarization state,as one of the important parameters describing the characteristics of light,is also a basic physical property of light.However,due to the lack of broadband high-efficiency and high-degree-of-freedom polarization control devices,polarized light has not been widely used to transmit spatial information.Manipulating the polarization of light has played a key role in a wide range of applications.If we need to implement the polarization control function based on traditional devices(e.g.half-wave plate and quarter-wave plate),we need to incident a specific linear polarized light,and the half-wave plate can only rotate the polarization plane by 90° for linear polarized light,which cannot achieve high freedom degree of polarization manipulation.Specifically,if a spatially integrated broadband polarization rotator can be realized,we can transfer spatial information by adjusting the polarization directions of different spatial positions.This type of integrated polarization rotator may have a wide range of applications in analytical chemistry,biology,communication technology,imaging and other fields.Aiming at the problem of achieving high degree of freedom polarization control of electromagnetic waves,this paper has achieved the following main results:1.We propose a new type of polarization rotator based on the all-dielectric metasurface to achieve the feature of broadband and high efficiency.Its structure is equivalent to the superposition of double quarter wave plates.Half of the structure can realize the conversion between linear polarized light and circular polarized light.High degree of freedom for manipulating the polarization can be achieved by rotating the direction of one quarter wave plate.2.An achiral all-dielectric polarization rotator is designed,which contains two quarter wave plates in a unit cell to generate left circular polarized light and right circular polarized light.By controlling the geometric parameters of a silicon antenna in the unit cell,we can realize the continuous control of the polarization angle of light from 0° to 90°.3.A high-order mode metasurface with a phase change of one period and a short-period mode metasurface consisting of only four V-shaped antennas in one period are designed based on the V-shaped metal antenna structure.The design of the surface structure can realize a large deflection angle for the incident light.4.We propose an all-dielectric multi-functional wave plate.The structure is designed as a two-dimensional all-dielectric chiral metasurface,which is almost completely transmission for incident left circular polarized light and almost total reflection for incident right circularly polarized light,and the transmitted and reflected light is circular polarized light with opposite spins.When linear polarized light of any polarization direction is incident on the structure,the designed structure can decompose the incident linear polarized light into two kinds of perfect circular polarized light with equal amplitudes and opposite spins.A new method for splitting linear polarized light is proposed.