Research On THz Absorber Based On Graphene

Graphene is a two-dimensional(2D)carbon material,has attracted many researchers' attention duo to its unique optical,electronic and mechanical properties.Especially,its unique band structure and excellent surface plasmons properties such as lower loss,stronger mode confinement and flexible tunability,which make graphene become an ideal material for terahertz absorber.Perfect absorption is characterized by the complete suppression of incident and reflected light and complete dissipation of incident energy.Terahertz absorber based on graphene is studied in this paper,as follows:First of all,we introduce the terahertz technology and the properties of graphene,and then,the tunable conductivity of graphene and the surface plasmons of graphene and their excitation modes are described and summarized in detail.Finally,the common numerical methods for electromagnetic simulation are introduced.Secondly,based on the above theory,the narrow band absorption properties of graphene strip and continuous graphene are analyzed by two-dimensional simulation.By the analysis of the single band absorber based on continuous graphene,the dual band absorber based on single layer graphene ribbon and the dual band absorber based on the combination of graphene ribbon and continuous graphene.The influence of the geometrical parameters and the chemical potential of graphene on the absorber is analyzed respectively.The numerical calculation shows that the proposed absorber can achieve more than 95% absorption in terahertz band.Finally,the broadband terahertz absorber based on graphene is analyzed by three-dimensional electromagnetic simulation,and the absorption bandwidth is broadened by using two layers of cross-shaped graphene arrays with different sizes.The single-layer patterned graphene has been analyzed first,according to the calculation,the bandwidth of the absorption efficiency above 90% is 1.13 THz in the case of single-layer cross-shaped graphene.By simply stacking the double layer cross-shaped graphene with careful design,the absorption bandwidth is twice as much as before.In addition,the absorption properties under different incident angles and graphene chemical potentials are also discussed in detail.Simulation results show that the absorber based on cross-shaped graphene array has wide-angle,broadband and flexible adjustable characteristics.