Research Of Terahertz Multi-Function Coding Metasurface Devices

In recent years,terahertz technology has received a lot of attention from all over the world for its important applications.As a new and efficient electromagnetic wave modulation device,coding metasurface has become a contemporary research topic.This article combines the two and designs several terahertz multi-function coding metasurface devices,which can meet the needs of multi-scene applications.The devices have significant prospects for future applications in terahertz communication,military and biomedical fields.The specific work is as follows:(1)A reflective terahertz multi-function coding metasurface device based on vanadium dioxide is designed.The required performances are obtained mainly by designing the parameters of the double split ring resonator and the cross structure in the top layer.The introduction of vanadium dioxide material cleverly enables it to work at dual frequency points,thereby achieving switching of different functions.The simulation results show that when the vanadium dioxide is in an insulated state,it has the function of generating the mode l=±1 vortex beam at a specific angle under the vertical incidence of a circularly polarized wave at 0.34 THz.When the vanadium dioxide is in a metallic state,it has the function of radar cross section reduction and beam splitting under the vertical incidence of orthogonal linearly polarized waves at 0.74 THz.(2)A terahertz full-space multi-function coding metasurface device based on vanadium dioxide is designed.The required performances obtained mainly by designing the parameters of the split ring resonator and the cross structure.The introduction of vanadium dioxide material cleverly enables it to work at dual frequency points and achieve switching between transmission and reflection modes.The simulation results show that when the vanadium dioxide is in an insulated state,it has the function of a metalens under the vertical incidence of a circularly polarized wave at 0.46 THz.When the vanadium dioxide is in a metallic state,it has the functions of single vortex beam generation,double vortex beam generation,anomalous reflection and beam splitting under the vertical incidence of orthogonal linearly polarized waves at 1.2 THz.(3)A reflective terahertz multi-function coding metasurface device based on graphene is designed.The Fermi energy of graphene is regulated by applying a bias voltage,thus the reflection amplitude of unit cells can be dynamically tuned.By compounding the coding sequence,a multi-function metalens with tunable focusing intensity is obtained.The simulation results show that the metalens can exhibit different subwavelength focusing effects under the vertical incidence of circularly polarized and linearly polarized waves at 0.914 THz.The normalized focusing intensity can be adjusted dynamically between 0.3 and 1 by modulating the Fermi energy of graphene.The multi-function coding metasurface devices designed in this paper have potential application value in future terahertz integrated systems,and have certain reference significance for the design of terahertz multi-function coding metasurface devices.