Tunable graphene-based terahertz absorber via an external magnetic field

A terahertz absorber that can be dynamically tuned via an external magnetic field is proposed. The absorber is composed of periodic gold-disks and an underlying graphene sheet on a dielectric/gold reflector substrate. Simulated results reveal that a new absorption peak appears under the perpendicularly applied external magnetic field. The new absorption peak under a 10 T magnetic field red-shifts from 14.22 THz to 4.47 THz as the Fermi level of graphene increases from 0.1 eV to 0.3 eV. At a fixed Fermi level, the new absorption peak blue shifts as the magnetic field increases. The new absorption peak can be enhanced by using multilayer graphene. The absorber is polarization independent. These results may promote the development and applications of flexibly tunable terahertz absorbers.