The Study Of Graphene-based Terahertz Range Surface Plasmon Characteristics

This thesis concerns about the gain characteristic of the longitudinal wave mode and thetransmission prope rty of the transverse wave mode of the surface plasmon in graphene inTHz range. Graphene-based passive waveguide structure was simulated and designed. Onthe basis of Maxwell’s equations and the material constitutive equations, the surface plasmonin graphene was described in the dielectric function. The dispersion and gain characteristicof the surface plasmon of the longitudinal wave mode was theoretically calculated, and theresults showed that the gain characteristics related to the carrier concentration and themomentum relaxation time. The carrier concentration of graphene which relates to thechemical potential and the physical parameters can be modified by an external electric field.In addition, the refractive index and propagation constant are also involved in the design ofthe waveguide structure. So the conductivity characteristics of graphene in the terahertz ba ndwere calculated and analyzed. Calculation results show that chemical potential affectsgraphene’s conductivity characteristics and further affects the dielectric characteristics ingrapheme. Graphene surface plasmon-based transmission structures are de signed by changeof the conductivity distribution in graphene. The transmission characteristics ofgraphe ne-based surface plasmons in different conductivity regions were simulated with theradio frequency (RF) mod ule of the COMSOL software. The results indicates that thetransmission of grapheme-based surface plasmon only exists in proper conductivity region.Y-shape waveguide based on the trans mission of Graphene-based surface plasmon issimulated and designed by applying different external voltages.