Unidirectional perfect absorber based on a one-dimensional topological photonic crystal heterostructure of Weyl semimetals.

We propose a tunable nonreciprocal optical absorber based on a one-dimensional topological photonic crystal heterostructure with Weyl semimetals. The study reveals that embedding a Weyl semimetal thin film at the interface of an asymmetric topological photonic crystal induces coupling between the topological interface states and the epsilon-near-zero effect of the Weyl semimetal. The results show that this coupling leads to hybridized Rabi splitting, and nonreciprocal perfect absorption is observed within the Rabi splitting region, which is closely related to the Fermi energy of the Weyl semimetals. This phenomenon is further elucidated through the analysis of the magnetic field intensity distribution. Additionally, the mode coupling can be tuned by adjusting the rotation angle, the thickness of the Weyl semimetals, and the axial separation vector. These findings hold potential applications in novel absorbers, sensors, and optical switches.