Research On Multifunctional Terahertz Metamaterial Devices

Metamaterials are a new type of synthetic materials made of periodic arrangement of electromagnetic resonance units,which have some specific physical phenomena and properties not found in materials in nature,as well as the advantages of light mass,low cost,thin thickness,easy processing,etc.They have become a research hotspot in the fields of radar stealth,optoelectronic devices,frequency selective surfaces,filters,wireless communication and sensors,and have high application value.At present,in order to meet different application requirements and integration,material research has expanded from the initial fixed metal structure to tunable metamaterial material structure to realize the transformation of metamaterials from single function to multifunction,making them more applicable and wider application prospects.In this paper,multifunctional terahertz devices such as band switchable and performance tunable absorber,electromagnetic induced transparent-absorber multifunctional device and polarization converter-absorber multifunctional device have been realized based on multiactive material hybrid terahertz metamaterial structure.The main research is as follows.(1)Firstly,a tunable absorber based on graphene and vanadium dioxide is proposed to realize the free switching between two broadband absorption bands.The effect of the active material on the absorption performance of the two bands is also studied,which can realize band modulation and absorption performance tuning.In addition,the structure has the characteristics of polarization insensitivity and wide angle incidence.On this basis,the function switching principle of the multifunctional metamaterial is analyzed and further demonstrated by analyzing the absorption principle of the metamaterial and calculating its equivalent impedance.(2)Based on the controlled phase transition properties of vanadium dioxide,a tunable multifunctional terahertz device based on vanadium dioxide metamaterial is designed,which can switch between electromagnetically induced transparency and broadband absorption.The proposed multifunctional device has a broadband electromagnetically induced transparency with over 90% transmission when vanadium dioxide is in the insulating state,and a broadband absorber with over 95%absorption when vanadium dioxide is in the metallic state.Modulation of vanadium dioxide allows for amplitude modulation of absorber and electromagnetically induced transparency properties.The sensor performance of the device in the electromagnetically induced transparent mode is also investigated.The electromagnetically induced transparency and absorption mechanisms are analyzed by structural simulations,electric field distribution,and light-dark mode coupling theory.(3)A multifunctional device combining polarization converter and absorber into the same resonator structure is designed by using the tunable property of active material and reconfigurable method to realize the free switching between three different operating modes of polarization conversion/absorption/reflection in the same operating band through the tuning of active material.The effect of different incidence angles on the performance of the multifunctional device is also studied.The operating mechanism of the multifunctional device is also analyzed by the surface current distribution and the electromagnetic resonance on different directional components.