Research On Tunable Terahertz Absorber Based On Metamaterial

Terahertz functional devices are the basis of various application systems of terahertz,and the terahertz absorber is one of the key components of terahertz systems,which has become a research hotspot.This article focuses on the study of tunable terahertz metamaterial absorbers,using vanadium dioxide(VO₂)and graphene materials to design tunable terahertz metamaterial absorbers with excellent performance.The main research contents are as follows:(1)An adjustable terahertz absorber with multiple defects embedded in VO₂film structure is proposed.It is composed of three layers of metal pattern layer on the upper surface,substrate and bottom metal plate,and vanadium dioxide is embedded between the upper surface and the substrate.The results show that the absorption at4.08THz and 4.33THz are 99.8%and 99.9%,respectively.By changing the ambient temperature,the absorption of the proposed absorber can be changed from 99.8%to1.0%with vanadium dioxide changed from insulating state to metal state.Changing the incident angle and polarization state,the results show that the absorption of the absorber is over 98%in the range of incident angle 0?40°under TE and TM polarization waves.(2)A tian-shaped structure embedded VO₂adjustable terahertz absorber is proposed,which is composed of a bottom metal plate,a dielectric layer and a tian-shaped defect layer.The tian-shaped defect layer is formed by partially filling the tian-shaped metal defects with VO₂cross.The transmission line model is used to calculate and analyze the absorber.The ambient temperature was changed to make the VO₂from the insulated state to the metal state,and the absorption of the absorber changed from 89.5%to 99.4%at 2.18THz and from 95.4%to 99.8%at 2.97THz.(3)An asymmetric double ellipse adjustable terahertz absorber is designed,which is composed of top layer patterned graphene,dielectric layer and metal bottom plate.Based on the ellipse pattern,the combination method is changed to improve the absorption bandwidth.The structural parameters are scanned and analyzed to obtain the optimal parameter size of the absorber.The calculation results show that the absorber has an absorption of more than 90%between 3.39THz and 5.96THz,and bandwidth is 2.57THz.In TE mode,the absorption rate is kept above 90%in the range of incidence angle 0?40°.(4)A semi-circular full-graphene metamaterial adjustable terahertz absorber is designed.Its structure is made of patterned graphene layer,dielectric layer and metal plate.When the chemical potential energy of graphene is 0.6e V with TE and TM polarization,the absorption of the absorber is over 90%between 7.22THz and11.18THz,and the bandwidth reaches 3.96THz.In addition,when the incidence angle changes in the range of 0?40°,the absorber maintains good absorption and stable absorption bandwidth with TE and TM polarization.In summary,the four designed terahertz absorbers can achieve tunable absorber performance by changing external conditions,and they have broad application prospects in the fields of communication and sensing.