Switchable and tunable bifunctional THz metamaterial absorber

The recent rise of active materials offers new opportunities for dynamically tunable metamaterial devices. However, metamaterial devices with a dynamically switchable function are in high demand. Inspired by previous studies, a dynamically switchable and tunable bifunctional THz (THz) metamaterial absorber based on vanadium dioxide (VO2) and graphene is proposed and investigated in this paper. Using the phase transition properties of VO2, the switchable performance between broadband near-perfect absorption and multiband near-perfect absorption can be achieved. When VO2 is in the metallic state, the designed metamaterial absorber acts as a broadband near-perfect absorber with more than 90% absorption in the frequency range from 2.6 THz to 7.5 THz. Alternatively, the designed metamaterial absorber with the same geometry can be transformed into a tunable multiband absorber when VO2 is converted to the insulated state. The performance of the absorber is analyzed by the multiple interference theory (MIT), which is in good agreement with the numerical simulation results. Due to the high symmetry of the structure, the presented absorber exhibits excellent polarization insensitivity and wide incident-angle stability, which opens a direction to design a new type of multifunctional metamaterial devices in the THz regime. (C) 2022 Optica Publishing Group