Active dual-tunable broadband absorber based on a hybrid graphene-vanadium dioxide metamaterial

Abstract

In this paper, we demonstrated an active dual tunable broadband terahertz absorber with polarization-independent characteristic, which consists of a hybrid graphene-vanadium dioxide (VO 2 ) metasurface array and a VO 2 ground plane separated by a dielectric layer. Numerical simulation results indicate that there are the most distinctive broad absorption spectra and a bandwidth with an absorptance over 90% as wide as 1.7 THz. Blue shift occur in the perfect absorption peaks of the absorber, which shift 1.18 THz from 0.1 eV to 0.6 eV by adjusting the Fermi energy of graphene. Additionally, by using external stimuli to change the conductivity of the VO 2 , the corresponding absorptance can be continuously adjusted from 28% to 99%, indicating that we can modulate the amplitude on the absorption spectrum. Therefore, we can achieve the tunable property in both frequency and amplitude through an external stimulus on the proposed simple structure. The electric field distribution and impedance matching theory can be explained the inherent physical mechanism. The absorber is effective to reach a 0°∼75° range of incident angles for both TE and TM polarizations. It indicates that the proposed absorber is beneficial to a new design method for high-performance terahertz devices.