Tunable Terahertz Metamaterial Absorber Based On Vanadium Dioxide And Graphene

In recent years,the academic community has been more interested in the design and research of terahertz functional devices,and has extraordinary application value in biomedical sensors,military radar,electromagnetic stealth,electronic communications and other fields.The structure and function of traditional electronic communication and other fields.The function and structure of traditional metamaterial absorbers can not fully meet the requirements of electromagnetic environment,so scholars have begun to study actively tunable metamaterial absorbers.In order to realize the tunable absorption characteristics of the metamaterial absorber,this thesis proposes two metamaterial terahertz absorber structures that combine vanadium dioxide and graphene materials with the super surface,and studies the proposed absorber from various aspects.The main research contents include:(1)A novel tunable multiband terahertz(THz)metamaterial absorber with switching function based on vanadium dioxide is proposed.The absorber has a four-layer structure.The bottom layer is a gold base plate,the third layer is a polyimide dielectric layer,the second layer is a silicon layer,and the top layer is a super surface.It is composed of two gold rings with openings,and vanadium dioxide materials of equal size are embedded It is composed of two gold rings with openings,and vanadium dioxide materials of equal size are embedded in the openings.Systematically study the geometric parameters of the structure.The material characteristics,the polarization angle of the incident terahertz wave and the oblique incidence angle will also further affect the absorption performance.Deeply analyze the multi-band absorption mechanism of the absorber.The simulation results show that when vanadium dioxide is in the insulating state absorption rate is 30.4%,which is far from the perfect absorption condition.At this time,the absorber is closed;When vanadium dioxide is in metal state,there are three absorption peaks,and the absorption rates at 2.53,5.7 and 8.67 THz are all greater than 99%,reaching perfect absorption conditions.At this time,the absorber is open.In addition,This absorption condition is relatively good,and the absorber is in open state at this time.In addition,make scientific changes to the performance changes of the absorber and the absorption mechanism of the absorber when changing the structural parameters.(2)It is mentioned that vanadium dioxide and graphene tunable broadband terahertz metamaterial absorbers contain vanadium dioxide and graphene materials in their supersurfaces,which enable the two materials to tune the absorbers at the same time period to achieve broadband absorption.The absorber has a total of four layers,from top to bottom,which are respectively super surface,silicon layer,polyimide dielectric layer and gold base plate.By scientifically controlling the Fermi level of graphene and the conductivity of vanadium dioxide,the absorber can have two different properties,namely,dynamic tuning and broadband absorption.The simulation results show that if the Fermi energy level of graphene is shown and the conductivity of vanadium dioxide is shown,the absorber will absorb in broadband,and the maximum absorption rate achieved in the band is 99.2%,and the minimum absorption rate is 82.1%,so that the requirements of broadband absorption can be fully met.The geometric parameters of the structure are studied in depth.At the same time,the polarization angle and oblique incidence angle of the incident terahertz wave as well as the specific performance of the material characteristics affecting the absorption performance are analyzed.In addition,the broadband absorption mechanism of the absorber is also analyzed scientifically.