Tunable unidirectional reflectionlessness based on vanadium dioxide in a non-Hermitian metamaterial

Abstract We propose a non-Hermitian metamaterial based on double split rings embedded in polymide and connected by vanadium dioxide blocks, and investigate the tunable unidirectional reflectionlessness at exceptional points in THz region. The conductivity of vanadium dioxide can vary from 2 × 10 2 S/m (insulator state) to 2 × 10 5 S/m (metal state) to shift the unidirectional reflectionlessnesses with unidirectional absorptions from 0.57 THz to 0.54 THz (the polarization angle θ = 0) and from 0.53 THz to 0.50 THz (the polarization angle θ = 90 ∘ ), respectively. In addition, unidirectional reflectionlessnesses also can be switched by adjusting the polarization angle θ of incident wave from 0 to 90 ∘ . With these findings, this study may open an attractive direction for a wide range of design possibilities in terms of unidirectional invisibility, diode-like device, filters and so on.