Information encryption driven by strength-switchable circular dichroism in vanadium dioxide based chiral metasurfaces

Abstract

Switchable polarization selectivity in reconfigurable metasurfaces is highly required in the field of information encryption. In this paper, we proposed a scheme of information encryption by using the giant and strength-switchable circular dichroism (CD) in VO2-based chiral metasurfaces in the mid-infrared region. A bar code information is encrypted and hidden into a VO2-based bielliptic cylinder (BC) and bielliptic cylinder enantiomer (BCE) constructed array. The metallic VO2-based BC and BCE arrays with the rotation angles (α=±14°) exhibit opposite CD (−0.94/0.94) at 6330 nm. With the VO2 transition from metallic to insulator phase, the giant polarization selectivity of both BC and BCE arrays will disappear. Hence, only when the specific environment temperature (>68 °C) and polarization state of incident light (LCP) are simultaneously satisfied, the secret information could be decrypted. The reversible CD in VO2-based chiral metasurfaces possesses great potentials for the application of optical information encryption.