Broadband tunable graphene-based metamaterial absorber

This paper proposes a graphene-based broadband tunable absorber with over 90% absorption and is polarization insensitive at mid-infrared frequencies. The proposed absorber consists of a periodic array of a dual electric LC (ELC) metamaterial unit fabricated on a multilayer structure composed of Au/BaF2/graphene materials from the bottom to the top. In the proposed structure, interaction between the dual ELC unit and the graphene sheet generates three close resonant frequencies, thus leading to a broadband absorption from 25.08THz to 39.56THz. By varying graphene’s chemical potential, wide absorption bandwidth can be flexibly tuned. Due to the approximate symmetry of the structure, the proposed absorber demonstrates polarization-insensitive and wide-angle characteristics. Simulation results demonstrate that the absorption efficiency of the proposed structure can be as high as more than 90% from 25.08 THz to 44.81THz with variation of the graphene’s chemical potential from 0.2eV to 0.8eV.