Vanadium dioxide-based phase gradient-switchable coding metasurface

In this paper, we design a phase gradient switchable coding metasurface based on vanadium dioxide (VO2). Each unit structure of the metasurface consists of three layers: a metal-VO2 composite structural layer, a polytetrafluoroethylene dielectric layer and a metal reflective layer. The metasurface utilizes the phase transition property of VO2 to dynamically reconstruct the phase gradient of the metasurface and realize the switching of two far-field beam functions. Simulation results show that when VO2 is in the insulating state, the phase difference between the units of the metasurface at 1.5 THz frequency is 90°, which can realize the anomalous deflection function of the 2-bit coding metasurface. When VO2 is transformed into a metallic state, the phase difference between the metasurfaces at the 2.1 THz frequency is 180°, which reconfigures the metasurface into a 1-bit phase-gradient coding metasurface and realizes the dual-beam beam splitting function. The phase gradient switchable coding metasurface designed in this paper enriches the flexibility of beam modulation and provides a new efficient and flexible beam modulation scheme for terahertz communication with potential applications.