Dual-layer graphene based tunable broadband terahertz absorber relying on the coexistence of hybridization and stacking effects

With the fast development of terahertz (THz) techniques, THz absorbers have a variety of applications. However, current designs have a series of shortcomings, such as low absorption rate and a fixed and narrow absorption bandwidth. To solve such problems, in this paper, we design a tunable broadband THz absorber, which consists of two layers of graphene structures: the top layer is arrayed with the graphene concentric hexagonal rings and the bottom layer is arrayed with regular graphene hexagon rings; therefore, both layers support hybridization and stacking effects. The coexistence of both effects achieves the absorption rate of over 90% in a broad band from 0.93 THz to 1.80 THz. Moreover, the absorption spectrum can be tuned by adjusting the graphene chemical potential, which is insensitive to both incident angle and polarization. Considering advantages such as a tunable broad absorption band, a high absorption rate and insensitive incident angle and polarization, the proposed dual-layer graphene based tunable broadband THz absorber can be a useful reference for absorber design even in other electromagnetic wavebands.