Design of Thermal-Switchable Absorbing Metasurface Based on Vanadium Dioxide

This letter presents a thermal-switchable absorbing metasurface (TSAM) based on the phase-change material vanadium dioxide (VO ₂ ). A thin film of VO ₂ was deposited on a sapphire substrate by a magnetron sputtering and then sliced into tiny chips, which can be regarded as thermal-switchable resistors. The surface structure of the TSAM element is realized by loading four VO ₂ chips into a square metallic loop. Polytetrafluoroethylene is used as the substrate due to its high thermal conductivity compared with foam. The TSAM is on the "absorbing" mode when it is heated underneath and is switched into the "reflecting" mode at room temperature. The absorbing mode is characterized by a wideband absorption (8–22 GHz). A TSAM prototype was fabricated and measured to verify this design.