Graphene-enabled chiral metasurface for terahertz wavefront manipulation and multiplexing holographic imaging

The ability of metasurfaces to simultaneously manipulate both the spin and phase of circularly polarized (CP) incident waves has attracted considerable attention from researchers. Here, we propose a reconfigurable double circular split rings (DCSRs) chiral metasurface. By introducing graphene and changing the Fermi level of graphene, dynamic circular dichroism (CD) can be achieved. The calculation results show that when the Fermi level of graphene is increased from 0.1 eV to 1 eV, the CD decreases from 0.72 to 0.09 at 0.839 THz, which provides a CD-tunable spin-controlled method. In addition, based on the graphene-enabled DCSRs, we design two metasurface arrays combining Pancharatnam-Berry (PB) phase and coding metasurface theory to realize terahertz CP wave switchable focusing and spin-controlled multi-pencil beam generation. Furthermore, we demonstrate the application of reflective holography for multiplexing circularly polarized waves. The results of this paper are expected to play a significant role in the future terahertz wireless communication system, multi-spectral imaging, and information encryption fields.