$\text{VO}_{2}$ Based Metasurface with Strong and Continuously Switchable Circular Dichroism in THz Region

Continuously switchable circular dichroism (CD) is highly required in wireless communication, real-time imaging, etc. In this paper, we proposed a continuously switchable chiral metasurface with $\mathbf{VO}_{\boldsymbol{2}}$ arcs embedded in an array of two gold split rings. The metasurface with insulator $\mathbf{VO}_{\boldsymbol{2}}$ reflects right circularly polarized waves and absorbs left circularly polarized waves, and the CD reaches 0.94 at 1.08 THz. With the phase transition of $\mathbf{VO}_{\boldsymbol{2}}$ from insulator to metallic phase, CD is dynamically and continuously switched from 0.94 to 0. The strong CD effect and the ability of continuously switching have great potentials in information encryption, chiral sensing, and chiral beam splitters.