Dynamically tunable single-layer VO2/metasurface based THz cross-polarization converter

Abstract

We demonstrate a single-layer THz metadevice that exhibits cross polarization transmission, a key factor to achieve optical activity. The device is comprised of a two-dimensional array of split ring resonators, each with a vanadium oxide (VO2) pad, integrated into one of the two capacitive gaps of the unit cell. Through numerical investigations we find that as the conductivity of VO2 increases the amplitude of the cross-polarization intensity decreases but maintains a wider broadband range than previously reported for single layered hybrid metamaterial (MM) devices as the VO2 transforms from the insulator to metallic phase. Also the asymmetric transmission, optically modulated by the device, is higher than that of multi-layered MM devices. Due to the materials properties of VO2, our results introduce a promising method that allows for an active sub-cycle dynamic tunability for THz polarization conversion with multiple modalities using optical, electrical or thermal switching. The study is an important step forward in developing compact, integrated, passive and active metadevices for polarization and wavefront control application in the THz.