Merging the Graphene Plasmons to Cavity Resonance for Controllable THz Multifunctional Metasurface

Merging the graphene surface plasmon resonance (GSPR) with the cavity resonance can provide a controllable multifunctional terahertz (THz) metasurface. A reflective metasurface containing a metallic resonator with discontinuities operates with a finite length and short dipoles. The insertion of graphene perturbs the field and can provide the GSPR along with the dipolar resonance of a short metallic dipole. Here, the field enhancement factor in graphene surface plasmons (GSPs) in all the generated GSPs mode indices significantly dominates the field confinement (FE) of metallic short dipolar formation. Consequently, the Fermi energy of graphene can provide the controllable multifunctional operation of the metasurface. The proposed metasurface can provide the conversion from linearly polarized (LP) to left-hand circularly polarized (LHCP) operation in the first band for all the values of Fermi energy of graphene. The operation is as LP to cross-polarization conversion (CPC) for Fermi energy up to 0.4 eV and LP to LHCP for Fermi energy up to 1 eV, in the second band. The metasurface provides the narrow absorption peaks and LP to right-hand circularly polarized (RHCP) operation in the third band for particular values of Fermi energy of graphene.