Thermally tunable dual channel toroidal metasurface on VO2 platform

Abstract

Active modulation of electromagnetic response in terahertz (THz) regime has gathered plenty of attention owing to its multifunctional applications. In this regard, metasurfaces integrated with VO2 as active material can create compelling pathways for actively controlling terahertz propagation. Hence, we have demonstrated a design of dual toroidal active metasurface by realizing plasmonic split-ring resonators on the VO2 thin film for dynamic and real-time control over THz wave propagation. These metasurfaces exhibit agile modulation of multiple resonances by exploiting insulator-to-metal transition (IMT) phenomena exhibited by VO2. For this purpose, sample temperature is varied from 26 to 110 °C. It is observed that at 110 °C, VO2 conductivity increased significantly resulting in a 46% peak amplitude modulation with respect to room temperature. Besides temperature induced tunability mediated by VO2 activated IMT, these metasurfaces manifest temperature tunable electric, magnetic, and toroidal modes which is further validated by rigorous multipole analysis. Hence, these outcomes provide a framework for implementing VO2 based temperature tunable THz metadevices for futuristic applications such as thermal sensors, modulators, terahertz switching, tunable absorbers, and photonic memory.