Design And Research Of Terahertz Broadband Reflector Based On Metamaterials

Nowadays,due to the increasing demand for communication,communication technology urgently needs to develop to a higher frequency band.Terahertz wave is the electromagnetic wave in the 0.1-10 Th Z band,which has a broad spectrum and excellent electromagnetic characteristics,and can be widely used in medical and health,security monitoring,communication interconnection and other fields.However,it is difficult for conventional materials to produce modulation effect on terahertz wave,which greatly limits the development of terahertz technology.However,the emergence of the metamaterial effectively solved the problem of the THZ wave can't modulation,with the different structure design of metamaterial periodic array can realize accurate control of THZ wave,for example,using metamaterials structure made of terahertz filter,THZ wave absorption,terahertz reflector and other different excellent function of terahertz devices have been developed.The terahertz reflector,as a key component in the terahertz communication system,can effectively control the transmission path of terahertz wave.Now,however,most of the reported work in the terahertz band reflector is through the surface etching of micro-nano grating structure,the structure surface sputtering metal film,or photonic crystal structure design,the major problems of reflector is ultra broadband characteristic of reflector and high reflectivity characteristics can not compatible at the same time,The reflection characteristics are easily affected by the polarization states of different incident electromagnetic waves.Therefore,based on the theory of metamaterial electromagnetic wave modulation related,around a metamaterial realize terahertz broadband reflector method to carry on the key discussion,designed and implemented several different structures and types of broadband terahertz high reflectivity reflector,to solve the problem of ultra broadband characteristic of reflector and high reflectivity characteristics cannot be compatible problems provides methods at the same time.The main contents of this paper are as follows:(1)Based on the traditional metamaterial structure,a double-layer grilly-shaped metamaterial terahertz reflector structure is designed.The reflector is composed of a classic sandwich structure(metal-dielectric metal),with a multi-grid metal layer and a flexible substrate polyimide medium layer.The metamaterial terahertz reflector proposed in this chapter can effectively solve the problem that the ultra-wideband characteristics of the terahertz reflector are incompatible with the high reflectivity characteristics.In the low frequency band from 0 to 4.0THz,the reflectance reaches2.04 THz in the band width above 98%,and the highest reflectance reaches 99%.In addition,by analyzing the distribution of surface current,surface magnetic field and surface electric field of the terahertz reflector,the physical mechanism of realizing ultra-wideband and high reflectivity of the terahertz reflector with double-layer grid is given,which provides a novel method for designing high-performance terahertz reflector.(2)In previous reports,most of the terahertz reflectors work in the low-frequency terahertz band,and there are few reports on the reflectors working in the high-frequency terahertz.In this paper,based on the double-layer grid metamaterial terahertz reflector,the surface resonance model of the reflector is improved to improve the surface current path of the metamaterial without reducing the structural size,A new type of fishnet metamaterial terahertz reflector structure is designed.The reflector can effectively realize electromagnetic modulation characteristics in high-frequency terahertz band,and has wide reflection bandwidth.It can achieve more than 98% reflectivity in 6.63~7.53 Thz band,and its reflection bandwidth can reach 0.9Thz,which further expands the working bandwidth of terahertz reflector in terahertz band.