Tunable multi-band terahertz absorber based on composite graphene structures with square ring and Jerusalem cross

In this paper, a polarization and angle-insensitive multi-band adjustable terahertz absorber is proposed and numerically investigated, which is composed of a kind of periodic array square graphene ring with a Jerusalem cross graphene sheet. The numerical results indicate that the peaks absorptivity reach 99.9%, 99.9%, and 98.5% at 2.02THz, 3.44 THz, and 7.58 THz, respectively. The three resonance frequencies can be dynamically tuned by varying the chemical potential. Its physical mechanism can be analyzed by using Coupled Mode Theory (CMT) and electric field distribution. Moreover, the designed absorber is insensitive to polarization state and has the capability of wide-angle absorptivity. As a sensing application, the sensing characteristics of this monolayer graphene metasurface structure were investigated. In addition, we can achieve multi-spectral absorption peaks by applying bilayer graphene composite structure arrays. The proposed terahertz absorber may benefit branches of science such as refractive sensors, solar absorption, stealth, and other optoelectronic devices.