Multifunctional Graphene Space–Time Coding Metasurface for Terahertz Holographic Imaging

ABSTRACT In recent years, the integration of electromagnetic metasurfaces with holographic imaging has witnessed significant progress. By engineering the array configuration of coding metasurfaces to manipulate both the amplitude and phase of scattered waves, high‐resolution imaging can be achieved. Nevertheless, conventional metasurfaces are usually restricted to reconstructing only a single holographic image on the imaging plane, which greatly limits their versatility. Here, we propose a graphene‐based terahertz space–time coding metasurface (STGDM) that employs 2‐bit unit cells together with temporal modulation to achieve equivalent 3‐bit phase control, enabling independent amplitude and phase modulation at the ±1st harmonics. Leveraging this mechanism, the STGDM achieves multiple advanced functionalities, including dual‐hologram reconstruction, simultaneous holography and beam steering, and controllable generation of dual vortex beams. Full‐wave simulations confirm that the proposed strategy effectively suppresses undesired harmonics while enhancing the system's degrees of freedom and functional reconfigurability. These results highlight the potential of STGDMs as compact and versatile platforms for high‐resolution imaging, security screening, multimodal sensing, and future 6G communication technologies.