Graphene Reflective Metasurface for Generating Spin-Controlled Vortex Waves in the Terahertz Regime

In this paper, a graphene reflective metasurface for generating spin-controlled vortex waves is proposed in the terahertz domain. By patterning the graphene cells into the phase distribution of corresponding topological modes, the proposed graphene metasurface is capable of generating a vortex beam carrying orbital angular momentum (OAM). More importantly, taking advantages of the Pancharatnam-Berry (PB) phase method, a spin-controlled OAM beam can be achieved in the reflective orientation. Compared with line-polarized OAM, the proposed spin-controlled beams can provide one more degree of freedom for THz wireless communication. Numerical simulations results demonstrate the spin vortex waves with various topological modes can be flexibly achieved by this graphene metasurface, which paves a way to generate spin OAM vortex waves for communication systems in terahertz.