Multi-channel perfect absorber based on a one-dimensional topological photonic crystal heterostructure with graphene.

The topological edge mode, which exists at the interface of a one-dimensional (1D) topological photonic crystal (PhC) heterostructure, provides the possibility to realize perfect absorption for its strong field localization effects. In this Letter, it is found that a huge absorption enhancement appears because of the excitation of topological edge mode, while the graphene is sandwiched between two 1D PhCs. The single peak perfect absorption is realized by means of the strong coupling of incident light and Tamm plasmon polaritons (TPPs) which is excited with Ag-PhC structure. Moreover, we use a heterostructure constructed by two PhCs, a monolayer graphene and Ag mirror to theoretically demonstrate that multi-channel perfect absorption can be achieved based on the effect of topological edge mode, TPPs and critical coupling. The angular selectivity of the proposed absorber is also investigated. Both of the absorption peaks are extremely narrow, and the absorption can be maintained more than 97% with the incident angle varying from 0° to 50°. Hence, our results may have potential applications in optical switches, thermal emissions, and narrowband selective filters.