A graphene based dual-band metamaterial absorber for TE polarized THz wave

摘要

A graphene based tunable metamaterial perfect absorber is designed, which is a classic and simple sandwich structure composed of a non-rotationally symmetric graphene pattern layer, a TOPAS dielectric layer and a thick enough gold ground plane. The dynamically adjustable absorption property of the proposed absorber is polarization sensitive, which is novel compared with the widely studied polarization insensitive metamaterial absorber. For TE polarized incident electromagnetic waves (EMW), the dual-band absorption can be generated at frequencies of 4.268 THz and 6.032 THz with peak absorption coefficients up to 99.99% and 99.79%, respectively. But for TM light, there is only one near unity absorption band located at about 4.148 THz. So it will have potential application value for the polarization state resolution of THz waves. The research mainly concentrates on the dual-band tunable absorption under TE polarized incident light. The factors affecting the absorption properties of the proposed absorber are studied by discussing the dependence of the geometric parameters as well as chemical potential and relaxation time of the graphene on the absorption. The simulation results are verified by using multiple reflection interference theory (MRIT) and impedance matching theory (IMT), and the results show that the theoretical results match well with the simulation results. The absorber can achieve good absorption performance in a wide range of incident angles for TE light. Furthermore, by selecting two different graphene chemical potential, good performance of THz switching can be realized. In addition, the application in the field of refractive sensing is also investigated in detail, and higher sensitivity and better figure of merit (FOM) can be obtained. Thus, the designed graphene-based dual-band THz metamaterial absorber has great potential in polarization resolution, EMW absorbing, THz switching, refractive index sensing and so on.