Research On Terahertz Filter Based On Vanadium Dioxide Metamaterial

With the rapid development of science and technology,people's demands for life are getting higher and higher.Advances in the field of optoelectronic technology,especially new technologies such as electro-optical sampling,photoconductive antennas and optical rectification,has provided great convenience for the study of terahertz,which has made remarkable progress in the research of terahertz technology and related devices.However,the development of terahertz devices is restricted by the immature technology of terahertz devices,so more attention is focused on the research of terahertz devices.At the same time,there is a greater demand for more frequency points with wider bandwidth and better filtering performance of terahertz devices Metamaterials are a new type of electromagnetic materials designed by man.They are composed of periodic array units of subwavelength size.They have many transcendent physical properties and can achieve functions that natural materials cannot,such as negative refraction and electromagnetic stealth.At present,more and more terahertz functional devices are designed in combination with metamaterials,which greatly promotes the development of terahertz technology.Based on the detailed description of the basic principles of metamaterials,the basic concepts of vanadium oxide electromagnetic metamaterials,the principles of phase transitions and the causes of phase transitions,this paper proposes a three-ring square split resonance ring based on vanadium dioxide(VO₂)a unit structure The terahertz filter and the double-opening square terahertz filter are modeled and simulated by HFSS three-dimensional electromagnetic field software,and the characteristics of the terahertz filter of these two structures are studied.The specific work is as follows:First,start with a unilateral split ring and gradually superimpose concentric square split rings to analyze the performance of the unit structure of the terahertz filter,and embed vanadium dioxide in the opening,and use the phase change characteristics of vanadium dioxide to obtain different rings.Count the influence of the metallic state and the insulating state of vanadium dioxide on the structure,resulting in the alternating effect of the stop band and the pass band.This structure shows that the three-ring square split resonant ring structure embedded with vanadium dioxide is a band-pass and band-stop dual-function filter,which realizes the switchable function at the frequency of0.83THz.The stopband bandwidth can reach 0.17THz,the passband bandwidth is0.03THz,and the passband loss is only about-2d B.In addition,this paper designs a new filter structure-a double-opening square resonant ring filter to study the influence of substrate thickness on the filter,and introduces vanadium dioxide strips to form a combined structure with the double-opening square resonant ring structure..By comparing the electric field distribution and current distribution,the filtering principle and performance are analyzed.Using methods such as changing the ring spacing,line width,vanadium dioxide strip size,etc.,the structure is simulated and analyzed,and the influence of the parameters on the filtering performance of the unit structure is obtained.The final optimized combined structure has the function of a dual-band terahertz band-stop filter and a single-band band-pass function.