Research Of Terahertz Metamaterial Reconfigurable Filter Devices

Terahertz technology has broad application prospects in wireless communication,security detection and medical imaging.As one of the most important terahertz functional devices,terahertz filters have the function of selecting signals of specific frequencies to pass through,so they have become one of the research hotspots in recent years.At present,the reported terahertz filters have a single function,which limits their application development.However,the terahertz reconfigurable filter can realize the mutual switching of filtering functions in the same structure,which has high research value.The discovery and application of tunable materials graphene and vanadium dioxide provide a new way to design terahertz reconfigurable filters.Therefore,this’s designs three terahertz reconfigurable filters based on graphene and vanadium dioxide.The main contents are as follows:1.A terahertz band-pass tunable filter based on vanadium dioxide is designed.The unit is composed of the traditional metal-dielectric-metal sandwich structure.Secondly,on this basis,a terahertz band-pass reconfigurable filter is further designed.The passband of the filter is switchable between 4.22-6.35 THz and 5.56-7.94 THz.Besides,the proposed filter has stable transmission characteristic in the incident angle range of 0°-35°.2.A terahertz band-pass/band-stop reconfigurable filter based on the vanadium dioxide square ring-shaped resonant structure is designed,and the filter possesses the advantage of structural simplicity.The simulation results show that:when the vanadium dioxide is in the insulating state,the filter can be regarded as a broadband band-stop filter,and the 3 d B bandwidth at the center frequency of 4.45 THz is 1.8THz;when the vanadium dioxide undergoes a phase change and transforms into the metallic state,the filter is switched from a broadband band-stop filter to a broadband band-pass filter which 3 d B bandwidth of 3.16 THz at the center frequency is 1.24THz.And due to the rotational symmetry of the proposed filter unit structure,the filter has better polarization insensitivity characteristic.3.A terahertz filter/absorber based on vanadium dioxide and graphene is designed.When the vanadium dioxide is in the insulating state and the graphene Fermi level E_f=0 e V,the device can be regarded as a broadband band-pass filter;when the vanadium dioxide phase changes to the metallic state and the graphene Fermi level E_f=0.9 e V,the device is switched as a broadband absorber.The three terahertz reconfigurable filters designed and studied in this paper have important research value for efficient regulation of terahertz waves,and have laid a foundation for the future development of terahertz technology.