Tunable circular dichroism of composite metamaterial on the basis of the phase transition of VO ₂

The circular dichroism (CD) effect characterized by different optical responses between left and right circularly polarized lights is widely applied for polarization-resolved detection and imaging. The tunable CD effect is of substantial importance in improving the detection sensitivity and imaging resolution. In this paper, we show that planar Z-shaped composite metamaterial embedded with VO ₂ that exhibits insulator-metal transition (IMT) can enable thermally tunable chirality. Simulated by the finite element method, the tunable CD effect can be achieved by changing the environment temperature to initiate the IMT of VO ₂ . We also demonstrate that the underlying mechanism of the CD effect generation is the electric multipole oscillation response in the vicinity of the VO ₂ gap in vertical direction. These findings not only provide a new strategy to change chirality and tune the effect of CD dynamically but also broaden its potential applications in polarization-resolved detection and imaging.