Graphene-Based Tunable Terahertz Polarization Switching Metasurface

Controlling the polarization state of electromagnetic waves can be used to transmit information, and therefore there is a need to design polarization conversion devices with excellent performance in communication systems. Devices designed using metasurface have superior polarization conversion performance. In addition, we want the metasurface to be tunable, i.e. the electromagnetic properties of the metasurface change as the external field varies, so we need tunable materials. In this simulation, the tunable material is graphene. When the Fermi energy level of graphene is at 0eV, the polarization conversion rate is observed to exceed 0.95 in the frequency bands of 2.09~3.96 THz and 4.24~4.45 THz, which achieves perfect linear-to-linear polarization conversion. A variation of the Fermi energy level of graphene of between 0.9 and 1 eV results in the metasurface achieving perfect linear-to-circular polarization conversion within the range of 1.8 to 2.38 THz. Ultimately, the frequency of the metasurface is observed to undergo a blue-shift concomitant with an increase in the Fermi energy level. Moreover, we have devised a left-rotating to right-rotating polarized metasurface that attains perfect left-rotating right-circular polarization when the Fermi energy level of graphene is 0.1 eV, with a polarization conversion exceeding 0.95 within the frequency range of 0 to 1.25 THz.