Weak and strong coupling regimes in a topological photonic crystal bowtie cavity

Topological photonics has attracted remarkable attention in recent years due to its ability to generate robust topological states, especially suitable for the study of cavity quantum electrodynamics. In this work, we present a theoretical study of a topological photonic crystal based on the 2D Su-Schrieffer-Heeger model, with corner states induced by a rotational operation on the axis parallel to the interface of two different topologies of a photonic crystal, forming a bowtie cavity. The studied topological photonic crystal presents inversion symmetry due to the rotation operation allowing the simultaneous existence of two non-degenerated corner states: one located in the weak coupling regime and the other in the strong coupling regime. Therefore, we present the emergence of distinctive effects from both regimes, such as the Purcell effect and Rabi splitting. We also address the study of the origin and evolution of the corner states resulting from the bulk-edge-corner correspondence. The topological bowtie cavity studied in this work combines the virtues of topological systems and the extreme confinement offered by cavities with bowtie architecture, which enriches the study of corner states in sophisticated topological structures. Published under an exclusive license by AIP Publishing.