Tunable bifunctional terahertz metamaterial device based on Dirac semimetals and vanadium dioxide

A tunable bifunctional terahertz (THz) metamaterial device based on Dirac semimetal films (DSFs) and VO2 is presented. The insulator-to-metal phase transition of VO2 enables bifunctional asymmetric transmission and dual-directional absorption to be switched in the THz range. When VO2 serves as a dielectric, tunable broadband asymmetric transmission of linearly polarized THz waves can be achieved. When VO2 is in a metallic state, the proposed device acts as a tunable dual-directional absorber with perfect absorption in both illumination directions. In each case, the response can be tuned by varying the Fermi energy of the DSFs. This offers a new pathway for the development of tunable multifunctional THz metamaterial devices.