Tunable quintuple-band polarization-insensitive wide-angle metamaterial absorber with single-layered graphene in terahertz range

A tunable terahertz quintuple-band metamaterial graphene absorber is presented in this paper. The designed absorber consists of single-layered graphene and a gold bottom plane separated by a dielectric layer. The simulation results show that the absorber has high absorption in five frequency bands of 0.93 THz, 1.72 THz, 2.39 THz, 3.05 THz and 3.72 THz with the absorption of 99.9%, 99.7%, 96.4%, 94.7% and 92.9%, respectively. Beyond that, the polarization sensitivity of the absorber is not obvious, and the incident range is large under both transverse-electric and transverse-magnetic waves. By changing the Fermi energy of graphene from 0 eV to 1.0 eV, the absorption can be flexibly changed from 20% to 100%, which opens up the possibility of graphene-based tunable devices.