Broadband of linear-to-linear and double-band of linear-to-circular polarization converter based on a graphene sheet with a π-shaped hollow array

Abstract

In this manuscript, we propose a tunable multifunctional reflection polarization converter based on a graphene sheet, which is decorated by a π-shaped carved-hollow array. Our design can achieve the linear-to-linear (LTL) polarization conversion with 3.58 THz bandwidth and two linear-to-circular (LTC) polarization conversion bands with opposite handedness, which originates from the excitation of the three graphene surface plasmons (GSPs) modes. The LTL polarization converter can be switched to the LTC polarization converter by only changing the medium height. The performances of this multifunctional reflection polarization converter under different geometric parameters, incident angles, and electron scattering time of graphene are investigated. Besides, it is found that the broadband of LTL and double bands of LTC have the blue shift with increasing the Fermi energy (Ef) of graphene. Especially, the conversion between line-to-left-circular and line-to-right-circular polarization converter can be achieved by changing Ef. All the simulation results are conducted by finite element method, and our design has potential applications in integrated terahertz systems.