Thermally Electrically Controlled and Brewster Operated Broadband/Multiband Ultrathin Metal-Free THz Absorber

The hybrid resonator of graphene and phase change material, vanadium dioxide (VO2), can provide a controllable electric-wall boundary for obtaining the multicontrolled resonances in a terahertz (THz) absorber. In the metallic phase, the electric wall-boundary is established through the VO2resonator, which provides multiple resonances with a merged spectrum resulting in a broad absorption band. In the insulating phase, the VO2layer acts as an impedance match layer, and an electric wall boundary is established through a graphene sheet. A large area graphene sheet can provide multiple plasmonic resonances with a narrow and separated spectrum depending on its Fermi energy. Thus, multiple electrically controlled narrow absorption bands are obtained. The resonance intensity of graphene can also be controlled through the angle of incidence through Brewster’s effect for a particular polarization of the incident wave. The proposed absorber can provide a way to implement an ultrathin structure of metal-free geometry which can be utilized in THz electromagnetic (EM) shielding and sensing applications.