Dynamic wavefront reconfiguration of terahertz waves enabled by dual optoelectronic material metasurface

Abstract In recent years, Terahertz metasurfaces, as a class of two-dimensional artificial materials, have been extensively employed in areas such as wireless communications, holographic imaging, and modern optics, owing to their capability to precisely control the electromagnetic waves. However, once the geometric parameters of most metal metasurfaces are determined, their working frequency and functions will be restricted. To overcome these limitations, we propose a THz metasurface based on graphene-silicon dual optoelectronic materials. For the THz metasurface design, a full 2 π phase coverage is achieved by rotating the upper graphene open ring under circular polarization incidence, and the continuous 2 π phase is obtained by regulating the lower strip graphene with electrostatic doping under linear polarization incidence. By combining geometric phases with Fermi levels, dynamic reconfigurations of various wavefronts can be achieved, including deflected beams, deflected vortex beams, and focused beams. Furthermore, the dynamic control of the reflection amplitude is achieved by adjusting the conductivity of the photosensitive silicon with pump light. Such versatile and dynamic control underscores the broad application potential of this dual-photonic metasurface in modern optics and wireless communication systems.