Fano-resonance in one-dimensional topological photonic crystal heterostructure.

We theoretically realize the Fano resonance with a high quality factor of 106 using a structure, which is constructed from three one-dimensional photonic crystals and a defect layer. The emerged Fano resonance can be attributed to the weak coupling between a Fabry-Perot cavity mode and a topological edge state mode provided by the topological photonic crystal heterostructure. Moreover, we experimentally reproduce this Fano resonance in the optical communication range with a high quality of 104. This may be useful reference for the study of applications of photonic topological states in integrated photonic devices and information processing chips.