Switchable Dual-Functional Metasurface for THz Absorption and Electromagnetically Induced Transparency

The metasurfaces based on nanostructure film play an important role in many fields. Usually, the properties and functions of metasurfaces are limited by their structure. Once the metasurface samples are processed, their functions have already been restricted. The dual-function device designed in this work utilizes the phase transition characteristic of vanadium dioxide (VO2). The entire layer of VO2 film is inserted between the double metal micro-nano structure. When VO2 film is in the metallic state after phase change, an isotropic narrow absorber is obtained in the terahertz (THz) region, which consists of a top Z-shaped meta-atom, a middle dielectric layer, and a bottom VO2 film. By adjusting structure parameters of VO2 film, perfect absorption is realized at the frequency of 0.525 THz with the overall absorption beyond 91%. When VO2 is in insulating state, the top Z-shaped meta-atom will interact with the bottom Z-shaped structure, and the resonance coupling leads to the appearance of electromagnetically induced transparency (EIT). The designed metal-VO2 hybrid metamaterial opens possible avenues for switchable functionalities in a single device.