Active modulation of absorption in terahertz hybrid metal-vanadium dioxide metasurface

Abstract

Metasurface-based devices are utilized to achieve high absorption in the determined frequency band and applied in sensing. The dielectric properties of vanadium dioxide (VO2) are sensitive to ambient temperature. The development of metasurface devices based on the tunable of VO2 has attracted a lot of attention. In this work, a tunable metasurface based on the VO2 layer is proposed and verified in the terahertz (THz) band. An absorption peak at 7.71 THz at room temperature is achieved based on the coupling effect between bright modes. This absorption peak is enhanced by optimizing the lattice constant of the unit cell (P) or metal particle diameter (D) in experiments. As the parameter P increases, the absorption peak is strengthened and moved to higher frequencies. Conversely, when the parameter D is increased, this absorption peak is moved to lower frequencies. An LC mode is suggested to reveal the influence of the structural parameters (P, D) on the absorption properties. Two measured figure of merit (FOM) (19.4, and 29) are obtained based on liquid sensing at room temperature. Since the resonance property of the VO2 layer is temperature reversible, the absorption performance of the metasurface is repeatable in the heating and cooling process. In the final experiments, the absorption peak is controlled in the heating and cooling process. Such a metasurface can be applied in liquid and temperature sensing.