A Dual-Band Tunable Metamaterial Near-Unity Absorber Composed of Periodic Cross and Disk Graphene Arrays

Abstract

A three-dimensional dual-band perfect absorber in the THz range (3–10 THz) is theoretically investigated. The absorber is composed of periodically placed cross- and disk-shaped graphene arrays on the top of a gold layer separated by a thick SiO$_{2}$ dielectric spacer. The simulated results show two absorption peaks with near-unity absorbance ( $99.923\%$ and $99.601\%$) at wavelengths 43.747 $\mu$ m and 69.94 $\mu$ m, respectively. Also, the absorber is insensitive to the polarization of the incident light and has a good tolerance to the incident angle whether it is TE or TM waves. Moreover, the peak wavelengths of the absorber can be flexibly modulated by varying the Fermi level $\mu _{C}$ of graphene while no need to refabricate the structure. This paper provides a new perspective for the design of graphene-based tunable multiband perfect THz absorbers, but not limited to THz absorbers, and may also be used in other THz graphene-based photonic devices.