A giantly chirality tunable terahertz metasurface based on 3D folded structure with vanadium dioxide

Abstract

Compared with ordinary chiral materials, chiral metamaterials possess giant chiral optical response, which have been widely used in many optical applications, such as circular polarizers, chiral light imaging and asymmetric transmission. Here, a tunable 3D folded metasurface based on vanadium dioxide (VO2) is proposed to achieve giant chiral optical effect in the terahertz band. The 3D folded metasurface comprises of two folded antisymmetric rectangular split rings resonators (SRRs). By folding the SRRs at a certain angle, the mirror symmetric structure was broken. The results shows that the circular dichroism (CD) parameter reaches a maximum of 0.83 at the folding angle of 45° and the spin-selective transmission is up to 0.89. The designed 3D folded metasurface can operate in a wide incident angle range of 0–55°. What’s more, by adjusting the conductivity of VO2, the dynamic tuning of CD can be realized, achieving the switch between the “ON” and “OFF” states. The proposed 3D folded metasurfaces provides an approach to realize the giant CD, which shows potential application in many fields, such as chiral sensing, polarization control, spin optical communication, and optical imaging.