Graphene spatiotemporal reconfigurable intelligent surface (GSRIS) for terahertz polarization-state manipulation and holographic imaging.

The integration of 2D materials and metamaterials/metasurfaces presents an effective approach for the intelligent, real-time dynamic control of electromagnetic (EM) waves in the terahertz (THz) frequency range. Herein, we demonstrate a graphene spatiotemporal reconfigurable intelligent surface (GSRIS) for THz polarization-state manipulation, multi-beam generation and holographic imaging using EM theory and full-wave EM simulations. The chemical potential of graphene can be changed through time-varying modulation, such as field-programmable gate arrays (FPGAs), of the electric field or voltage. By dynamically controlling the spatiotemporal chemical potential of graphene, both the amplitude and phase of orthogonally polarized reflected waves can be simultaneously adjusted, enabling polarization state manipulation at different harmonics, multi-beam generation, and holographic imaging. As a proof of concept, a multifunctional GSRIS designed for 1.3 THz demonstrates polarization-state manipulation and multi-beam generation at the +1 order harmonic, as well as high-quality holographic imaging at the -1 order harmonic. The presented GSRIS provides a novel approach for designing THz circuits and systems, which can exhibit various potential applications in imaging, sensing, beam control, and 6G wireless communications.