A circular dichroism switchable terahertz chiral absorber based on vanadium dioxide

Abstract This paper proposes a tunable terahertz chiral metasurface absorber based on the temperature-dependent vanadium dioxide (VO 2 ) material. Through theoretical analysis and electromagnetic simulations, the metasurface achieves circular dichroism (CD) values of −0.909 and −0.917 at frequency of 1.82 and 3.15 THz when VO 2 in its metallic state, respectively. For instance, the absorptivity for incident right-handed circularly polarized (RCP) waves are 97.2% and 98.8% while they are only 6.3% and 7.1% for left-handed circularly polarized (LCP) waves. Meanwhile, dynamic tuning of the metasurface’s CD characteristics can be achieved by changing the conductivity of VO 2 , demonstrating excellent control flexibility. The physical mechanism behind the chiral response of the metasurface was investigated and the thermally controlled switchable near-field imaging of the array structures were discussed. The proposed metasurface, which features a simple structural design, showing great application potential in terahertz chiral light detection and image encryption.