Tunable Broadband Terahertz Beam Splitting using Gated Graphene Metasurfaces

Active control of split ratios in terahertz (THz) beam splitters holds substantial potential for applications in imaging and spectroscopy. In this study, we introduce an approach for electrically controlling THz beam splitting with near non-dispersive characteristics, using the metasurface hybridized with single-layer graphene. Specifically, the resonant frequency of the metasurface is meticulously chosen to provide an enhanced effective conductivity that is almost frequency-independent. Furthermore, the split ratio can be manipulated by adjusting the gate voltage applied to graphene, thereby altering the effective conductivity of the hybrid metasurface without affecting its non-dispersive transmission and reflection characteristics. The feasibility of our approach is confirmed by the near non-dispersive split ratio across a wide operating frequency range, from 0.5 to 1.5 THz. The demonstration of this efficient, broadband, and tunable beam splitting ability validates the potential of gated graphene metasurfaces for advanced THz applications.