Graphene-based tunable terahertz metamaterial absorber with dual-band absorption and triple-band absorption

Abstract This paper presents a tunable wide-angle terahertz absorber with dual-band and triple-band absorption based on a monolayer graphene, comprising a dual-ring graphene top layer, a SiO2 dielectric layer, and a gold substrate. Under normal incidence, simulation results show that three absorption peaks exceeding 95% at 0.90THz, 1.42THz and 1.79THz for the TE mode, while the TM mode yields a dual-band response at 1.20 THz and 1.65 THz. The impedance at the absorption peaks is almost perfectly matched with the free-space impedance. Systematic analysis reveals that both the dual-band and triple-band absorption arise from the superposition and coupling of the dual-ring graphene. The resonant frequencies are tunable by modulating the graphene Fermi energy level. The absorber has distinct polarization-dependent resonant modes and maintains stable absorption performance under both TE and TM modes for incident angles up to 40°. Such a design can provides new ideas and methods for multi-band graphene-based tunable terahertz absorbers.