Tunable bidirectional perfect THz absorber realized by graphene-based one-dimensional photonic crystals

In this paper, a perfect absorption structure of graphene-based one-dimensional photonic crystals (1DPC) with tunable absorption channels and absorptivity is proposed. The proposed structure can achieve four perfect absorption peaks with the absorptivity of 99.31%, 99.88%, 99.74% and 99.32% at the same time, and the absorptivity of all absorption peaks is more than 95%. By adjusting the period number of 1DPC, the number of absorption peaks and absorption efficiency can be changed. By changing the chemical potential and relaxation rate of graphene, the absorption of the proposed structure can be dynamically tuned. And the influence of structural layer thickness on absorption property is also explored. In addition, we use this structure to design two different bidirectional absorbers. The designed bidirectional absorber can tailor the perfect absorption frequency with the absorptivity of more than 99.51%, and can change the absorption channel from single channel to double channel and double channel to multi-channel under the forward and backward incidence. This work not only fills the gap in the design of bidirectional perfect absorbers for 1DPC, but also provides a scheme for the design of multifunctional devices.