Research On Terahertz Metasurface Characteristics Based On VO₂

Although terahertz technology has shown broad development prospects and great application value,there are still many problems that need further research and improvement.Among them,the lack of tunable terahertz functional devices has limited the wide application of terahertz technology.In this regard,the researchers combined the original technology with the active medium and carried out related research.In various active media,vanadium dioxide(VO₂)is a high-quality optoelectronic functional material with insulation-metal phase transition characteristics under the external light field,electric field,and heat pump.The change in conductivity has reached 3 to 5 orders of magnitude.Therefore,this paper proposes two types of terahertz functional devices based on composite VO₂ metasurfaces,which can achieve extremely high modulation depth and tunable range under external thermal excitation.The specific research contents are as follows:First,based on the insulation-metal phase transition characteristics of VO₂,a tunable terahertz intensity modulator with a cross-type metasurface structure is proposed in this study.As the temperature increases,the phase state of VO₂ changes,and the modulation depth of the device for terahertz radiation also increases.Numerical calculation results show that the maximum tunable range of THz wave transmittance at the modulation temperature close to room temperature is 6%-86%,and it has a good modulation effect on the terahertz signals of TE mode and TM mode.The processing is difficult and easy to implement.The proposed device will promote the practical application of THz functional devices such as filters,sensors,modulators,and switches.Secondly,based on the insulation-to-metal phase transition characteristics of VO₂,a wideband tunable terahertz absorber with an L-type metasurface structure is proposed in this study.According to the results of numerical calculations,under the effect of external thermal excitation,the absorption rate of the device can be continuously adjusted from 5%to 100%,and in the frequency range of up to 2.0 THz,the absorption rate is higher than 80%.The absorption effect,especially at 1.96 THz,achieves near-perfect absorption.Besides,the device can work normally when the incident angle of the signal is less than 50°.At the same time,because the phase change response time of VO₂ is on the order of picoseconds,it has an ultra-fast response time.According to the research results in this article,we believe that composite terahertz devices based on VO₂ phase change materials have the advantages of the high depth of response to the external environment and fast modulation speed.The technology is easy to extend to other frequency ranges,including terahertz imaging,communication Many fields including modulation,modulation,and filtering have certain practical value.