Research Of The Terahertz Absorber Based On Vanadium Dioxide Metamaterial

Terahertz(THz)wave is an electromagnetic wave in the frequencies range from 0.1-10THz,because the THz wave have unique optical properties,which has attracted great interest,and making it widely used in wireless communication,security detection,radar imaging technology,biomedicine and other fields.However,the untunability and large energy loss of traditional metal materials greatly limit the application and development of THz technology in many fields.The vanadium dioxide(VO2),as a metamaterial with excellent conductive properties and phase transition properties,has a phase transition temperature of 68℃.We can transition it from insulator state to metal state by electrically,thermally and photo-controlled induced methods.And the conductivity of VO2 will change between 200 S/m～200000 S/m during phase transition.Therefore,vanadium dioxide metamaterial can largely solve the problem of untunability of terahertz functional devices,and promote the development and application of terahertz technology and terahertz optoelectronic functional devices.In this paper,we mainly study the tunable THz absorber based on vanadium dioxide metamaterial.The specific research work is as follows:1.We investigate a tunable dual broadband terahertz absorber based on vanadium dioxide.We placed two identical metasurface structure diagonally at the top of the absorber to form a terahertz absorber with double broadband absorption,and the two absorption broadband reached 97.5%and 90.1%in the range THz 0.796～1.32 THz and 2.96-3.52 THz,respectively.These two absorption broadband are excited by plasmon resonance and high order mode resonance caused by coupling effect.The amplitude of two absorption broadband of the absorber can be dynamically modulated by adjusting the conductivity of theVO2,the amplitude modulation depth of the absorber can reach more than 90%in the frequency range 0.58 THz to 1.62 THz and 2.48 THz to 3.53 THz when the conductivity increases from 500 S/m to 200000 S/m.In addition,we study the effect of incident angle and polarization angle on the absorbing property of the absorber,and find that the absorber not only shows obvious polarization insensitive characteristics,but also can still maintain excellent absorption performance at a wide incident angle.2.We study a broadband terahertz absorber based on vanadium dioxide with dual-control adjustable function.The terahertz absorber model is a simple three-layer structure consisting of a Dirac semimetal resonant ring structure,SiO2 dielectric layer and V02 substrate.The absorber produces an absorption broadband in the frequency range 0.412～0.72THz,and the absorption rate of the absorber reaches 97%.The dynamic modulation of the absorption broadband of the absorber can be realized by adjusting the conductivity of the VO2,when the conductivity increases from 500 S/m to 50000 S/m,the modulation depth of the amplitude of the absorber can reach more than 48%in the frequency range 0.28 THz to 0.83 THz,while the amplitude modulation depth at the frequency 0.39 THz and 0.73 THz is as high as 70%and 69.1%,respectively.While the Fermi level of the Dirac semimetal can be adjusted to modulate the amplitude and frequency of the absorbing broadband.Thus,the absorber model has the function of dual control and adjustable.In addition,we study the effect of the incident angle on the absorption performance of the absorber,and find that the absorber still has good absorption performance at a wide angle of incidence.