Switchable Multi-Functional VO2-Integrated Metamaterial Devices in the Terahertz Region

In this paper, we present a multi-functional terahertz metamaterial device based on the gold and vanadium dioxide (VO ₂ ). Availing of the phase transition characteristic of VO ₂ , the switchable performance between perfect absorption and broadband asymmetric transmission (AT) can be realized. When VO ₂ acts like a metal, the proposed metamaterial device behaves as a selectively perfect absorber for linearly polarized lights. By transforming the phase of VO ₂ into isolating state, broadband AT with high efficiencies over 90% can be achieved in the region from 1.5 THz to 2.5 THz. Moreover, perfect polarization conversion can be simultaneously realized associated with the AT effect. The Fabry-Pérot-like cavity model and the electric field distributions are employed to explain the physical mechanism of the above phenomena. Besides, the proposed metamaterial shows a high tolerance to the incident angle for achieving perfect absorption and broadband AT effect. Our designed device may provide a new avenue for developing multi-functional metamaterial devices in the THz region.