Terahertz bandstop-to-bandpass converter based on VO2 hybrid metasurface

We experimentally demonstrated a terahertz (THz) bandstop-to-bandpass converter based on vanadium dioxide (VO2) hybrid metasurface. The unit cell consists of gold and VO2 hybrid structures standing on a high resistance silicon substrate. Simulation and experimental results show that for y-polarized waves, the device's function converts from bandstop filtering to bandpass filtering when VO2 transits from insulating state to metallic state induced by the Joule heat produced by the heating wire on the surface. The operation principle is explained by combining the surface current distribution and the LC equivalent circuit model. For x-polarized waves, when VO2 changes from insulating state to metallic state, the response of the device to THz wave changes from single resonant state to double resonant state. This phenomenon originates from the conductance coupling effect in plasma optics. The proposed device realizes active control of THz waves and is expected to be used in the fields of THz communication, imaging and electromagnetic switching.