A Vanadium Dioxide-Based THz Metasurface for Dual-Function Switching Between Wideband Absorption and Polarization Conversion

In this work, a multifunctional metasurface based on vanadium dioxide (VO₂) is designed. By inserting a vanadium dioxide layer into the dielectric layer, the wideband absorber and polarization converter can be switched in the terahertz band. When vanadium dioxide is in the metallic phase, the multifunctional metasurface acts as a broadband absorber in the 9.97–23.31 THz range. When the vanadium dioxide is insulating, the metasurface acts as a polarization converter, with a conversion efficiency greater than 90% from linear polarization to cross-polarization in the range of 2.65–8.26 THz. In addition, the effects of incidence and polarization angles on the metasurface properties are also discussed. This study shows that multifunctional metasurfaces have broad application prospects in terahertz optical switches, electromagnetic stealth technology, modulators, and communication systems.