Graphene-Based Tunable Polarization Insensitive Dual-Band Metamaterial Absorber at Mid-Infrared Frequencies**Supported by the National Natural Science Foundation of China under Grant No 61001018, the Natural Science Foundation of Shandong Province under Grant No ZR2012FM011, the Shandong-Provincial Higher Educational Science and Technology Program under Grant No J11LG20, the Qingdao City Innovative Leading Talent Plan under Grant No 13-CX-25, the THz Science and

Abstract

A graphene-based tunable dual-band metamaterial absorber which is polarization insensitive is numerically proposed at mid-infrared frequencies. In numerical simulation the metamaterial absorber exhibits two absorption peaks at the resonance wavelengths of 6.246 μm and 6.837 μm when the Fermi level of graphene is fixed at 0.6 eV. Absorption spectra at different Fermi levels of graphene are displayed and tuning functions are discussed in detail. Both the resonance wavelengths of the absorber blue shift with the increase in Fermi level of graphene. Moreover, the surface current distributions on the gold resonator and ground plane at the two resonance wavelengths are simulated to deeply understand the physical mechanism of resonance absorption.