Design And Research Of Terahertz Spectral Tuning Meta Surface Devices

Electromagnetic metasurfaces have gradually become research hotspots in the terahertz,infrared and microwave fields due to its light weight,easy integration and strong spectrum control capabilities.However,due to its lack of passive,narrow-band characteristics and constant electromagnetic characteristics,dynamic adjustment or adjustable resonance,ultra-wideband has become a new trend in current electromagnetic adjustment research.1.Proposed a terahertz absorber based on a metal-dielectric-metal(MIM)structure.Combined with equivalent dielectric constant,permeability,wave impedance and equivalent circuit model to explain the wave absorbing mechanism and predict the resonance point.And then quantitatively reflect the relationship between structure size and resonance frequency.Subsequently,by introducing the phase change medium GST,the tunable function was realized,and the influence of the thickness of the dielectric layer and the structural feature size on the resonance curve and frequency modulation was analyzed.The best peak absorption rates of the amorphous and crystalline states that can be finally achieved are 99.66% and 88.59%,respectively,and the tuning frequency reaches 28.28%.2.Explore broadband electromagnetic regulation based on multi-layer terahertz metasurfaces.In view of the narrow-band characteristics of a single-layer metasurface,ultra-wideband spectrum control is achieved through multi-layer coupling.For example,by superimposing three resonant operating points,a terahertz band-rejection filter with a band close to 130 GHz(373 GHz to 502 GHz)and having ultra-flat transmission characteristics is achieved.The rising and falling steepnesses are respectively 1930% / THz and 697% / THz;Based on the physical model of the device and the characteristics of the resonant operation,an equivalent circuit model is established to explain the mechanism of broadband control and reveal the relationship between the structural feature size and the resonant frequency and bandwidth.In particular,through structural improvements and multilayer coupling characteristics optimization,the broadband filtering characteristics of the multilayer metasurface are improved to achieve ultra-flat band-stop characteristics from 386 GHz to 578 GHz,with in-band suppression of more than 96% and rising and falling steepness of up to 2100% / THz,2600% / THz,-3db bandwidth is 256.7GHz,-20 db bandwidth is 191.1GHz,and rectangular coefficient k is as high as 0.791.