Tunable reflective spin-decoupled encoding metasurface based on Dirac semimetals

Multiple functional metasurfaces with high information capacity have attracted considerable attention from researchers. This study proposes a 2-bit tunable spin-decoupled coded metasurface designed for the terahertz band, which utilizes the tunable properties of Dirac semimetals (DSM) to create a novel multilayer structure. By incorporating both geometric and propagating phases into the metasurface design, we can effectively control the electromagnetic wave. When the Fermi level (E_F) of the DSM is set at 6 meV, the electromagnetic wave is manipulated by the gold patch embedded in the DSM film, operating at a frequency of 1.3 THz. When the E_F of the DSM is set at 80 meV, the electromagnetic wave is manipulated by the DSM patch, operating at a frequency of 1.4 THz. Both modes enable independent control of beam splitting under left-rotating circularly polarized (LCP) and right-rotating circularly polarized (RCP) wave excitation, resulting in the generation of vortex beams with distinct orbital angular momentum (OAM) modes. The findings of this study hold significant potential for enhancing information capacity and polarization multiplexing techniques in wireless communications.