Research On Vanadium Dioxide Based Broadband THz Metamaterial Absorbers With High Tunability

Metamaterials have extraordinary physical properties and unprecedented flexibility in han-dling electromagnetic waves,which can fill the so-called"THz gap".The superior performance of electromagnetic metamaterials has made experts and scholars interested in the study of their absorbing properties.In the metamaterial absorber,the incidence can be changed by adjusting the permittivity and permeability of its structural unit.The propagation behavior of electromag-netic waves in metamaterials,so as to achieve the purpose of regulation.Vanadium dioxide?VO₂?will change from an insulative phase to a metal state near 68°C,and with a significant change in electrical conductivity of up to 3 to 4 orders of magnitude,the dielectric constant and magnetic permeability change with the change in electrical conductivity Therefore,when VO₂is applied in a metamaterial absorber,it can be dynamically adjusted,which has great practical application value.This paper selects VO₂ with phase change characteristics as the research object,combines VO₂ with metamaterial structure,and studies a terahertz electromagnetic metamaterial absorb-ing structure based on VO₂ with ultra-wideband and highly adjustable characteristics.The main research contents include the following two parts:The first part is the preparation of VO₂ thin film.Using magnetron and tube furnace equip-ment and based on the experimental results in the laboratory,a comparison experiment was performed on different oxygen and argon ratios and different substrates to prepare a relatively pure VO₂ film,and then use SEM and XRD to characterize the sample,and finally obtain the parameters required to prepare a more pure VO₂ film is the substrate is c-sapphire,the substrate temperature is 575°C,the sputtering power is 120 W,the sputtering The shooting time is 1 h,O2:Ar=2:20 and the working pressure is 0.8 Pa.In the second part,a terahertz metamaterial absorbing structure based on VO₂ is designed based on the preparation of VO₂.This paper mainly studies the pattern structure of VO₂,the conductivity of VO₂?that is,the phase change characteristics?,the thickness of the VO₂ layer,the thickness of the SiO₂ dielectric layer,the bottom Au layer and the angle of incidence angle.The simulation shows that in the frequency range of 0.61 to 1.36 THz,the metamaterial main-tains its broadband absorption performance in the field of view of±50°;the numerical results show that the high absorption behavior depends on the characteristics of VO₂,and it can be used in the frequency band of 0.2 to 2.0 THz.Achieve highly dynamic tuning;when VO₂ is in the middle jump state,perfect absorption will occur at 1.73 THz;Moreover,it was proved that the absorbing condition also depends on the incident angle of the electromagnetic wave.When the incident angle is close to 70°,the TE?TM?polarized incident wave shows a significant additional absorption band near 0.6 THz?1.4 THz?.The metamaterial absorber has both ultra-wideband and highly tunable characteristics.This research has great research significance for the application and development of terahertz devices.