Wideband polarization-insensitive metamaterial perfect absorber based on bilayer graphene metasurface

摘要

In this article a polarization-insensitive broadband adjustable THz metamaterial absorber is proposed and examined. The absorber is constructed of a periodic array of patterned graphene elements that is like the star as unit cell, placed on a SiO2 dielectric layer and it is terminated by a gold reflector. The simulation results display that the proposed absorber with single graphene layer has bandwidth of 1.96 THz for absorption above 90 with the peak absorption of 98.45 in 4.18 THz. This absorber with two graphene layers covers the frequency range of 2.99-6.16 THz for absorption > 90 with the highest absorption of 99.99 at 5.30 THz. The bandwidth for absorption above 99 is 0.72 THz. The absorption curves for TE and TM modes similar together. The electric fields and current surface of proposed absorber have been investigated on low and peak absorption frequency in TE and TM modes. This structure has features such as polarization independent for normal incident waves owing to its symmetric structure, good bearing angle of incident wave and adjustable by altering the Fermi level of graphene. Due to these properties, the broadband metamaterial perfect absorber is suitable for applications such as camouflage systems, imaging, detector, energy harvesting, and modulators.