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 (VO2). A thin film of VO2 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 VO2 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.