Robustness of the topological interface state in a 1D photonic crystal resonator with an air-gap

Topological photonics have emerged as a framework to manipulate light for low-loss and compact photonic applications, such as waveguides, beam splitters, isolators, and lasers, due to their immunity to imperfections or structural disorder in bulk [1] . One-dimensional topological photonic crystals (1D-PhCs), particularly, have received great attention due to their simple architecture, convenient fabrication process, and relatively easy prediction of their optical characteristics using standard simulation methods. Recently, a topological nanocavity laser with high Q factors of over 10,000 was demonstrated at the interface between two topologically distinct 1D photonic crystals (PhC) [2] .