A VO2-based terahertz broadband absorption and polarization conversion metasurface

Abstract

This work investigates a switchable terahertz metasurface based on vanadium dioxide (VO2). Through temperature-induced modulation of the VO2 conductivity, reversible switching between broadband absorption and polarization conversion was achieved. The properties of the designed metasurface were analyzed using CST simulations. When VO2 is in the metallic phase, the proposed metasurface achieves an absorptivity above 90% over 1.80–4.40 THz, with a corresponding relative bandwidth of 83.9%. Moreover, stable absorption is maintained over wide ranges of polarization angles and incident angles. In the insulating phase, over 1.51–3.86 THz the metasurface achieves a polarization conversion ratio (PCR) above 90%, and a relative bandwidth of 87.5%. The physical mechanism was clarified through equivalent circuit modeling, impedance matching analysis, electric-field distributions, phase responses, and surface current characteristics. Owing to its simple configuration and excellent electromagnetic performance, the proposed metasurface provides a promising platform for tunable terahertz absorption, polarization manipulation, and multifunctional integrated devices.