Research On Terahertz Super Metasurface Based On The Phase Transition Characteristics Of Vanadium Dioxide

A metasurface structure is a microstructure that can be artificially designed with different electromagnetic wave transmission characteristics.By applying the metasurface to the terahertz band and using the controllable characteristics of new materials,the terahertz wave can be regulated quickly and efficiently,which greatly promotes the development of terahertz devices.In this dissertation,a metal-insulator phase change material,vanadium dioxide(VO₂)and gold(Au),will be used to design a hybrid metasurface structure to achieve the reconstruction response of the metasurface structure and the resonance of the terahertz wave Mode.The specific research content of the paper is as follows:1.In this article,we use COMSOL Multiphysics software to simulate some simple terahertz metasurface s.In the simulation of rectangular and cross-shaped metasurfaces,both of these metasurface structures have a resonance peak in the frequency spectrum.Using the electric field distribution of the two structures to analyze the reasons of the resonance peaks,we found that the generation of the two metasurface resonance peaks is related to the horizontal arm length of the structures.Changing the length of the horizontal arm can also change the position of its resonance peak.2.Vanadium dioxide has an insulator-metal phase transition characteristic.The phase transition temperature is 68? during the heating process and 64? during the cooling process.If vanadium dioxide is used in the terahertz supersurface structure,the structure reconstruction phenomenon can be realized,and the tunable terahertz wave can be realized automatically.The terahertz metasurfaces are compared from the local surface plasmon nanospheres,which illustrates the correlation between the geometric parameters of the metasurface structure and the generation of terahertz metasurface resonance peaks.3.A VO₂-Au hybrid cross-shaped metasurface structure is designed,which consists of a rectangular structure made of Au and a "T" structure made of VO₂.Below the phase transition temperature,the structure exhibits the resonance characteristics of a rectangular metasurface structure,and above the phase transition temperature,the structure exhibits the resonance characteristics of a cross-shaped metasurface structure.After simulation,the structure has a resonance peak with a transmittance of only 3% at 1.41 THz at low temperature(45?).At high temperature(75?),there is a resonance peak with a transmittance of 9% at 0.92 THz.The twodimensional spectral lines of continuously changing temperature and transmittance are used to prove the resonant modal transition process of the THz transmission spectrum and the continuous tunable characteristics of the resonator.The electric field analysis of the structure is the same as that of the rectangular structure at low temperature,and the electric field distribution of the structure is the same as that of the cross structure at high temperature.It is further proved that VO₂ has a reconstructed response in the terahertz metasurface.4.VO₂-Au hybrid cross-shaped structure super-surface is designed to realize the active control of dual-mode resonance to single-mode resonance.At low temperatures,it exhibits Lshaped resonance characteristics,and there are two resonance modes.It exhibits a cross-shaped resonance characteristic at high temperatures,but only a single resonance mode exists.Based on the electric field distribution of the metasurface structure,the physical mechanism of the hybrid metasurface resonance characteristics is analyzed.The two-dimensional spectral line and transmittance at continuously changing temperature are used to illustrate the resonance mode transition process of the THz transmission spectrum and the characteristics of continuous temperature tuning of the resonator.