Cascade Enhancement and Efficient Collection of Single Photon Emission under Topological Protection

High emission rate, high collection efficiency, and immunity to defects are the requirements of implementing on-chip single photon sources. Here, we theoretically demonstrate that both cascade enhancement and high collection efficiency of emitted photons from a single emitter can be achieved simultaneously in a topological photonic crystal containing a resonant dielectric nanodisk. The nanodisk excited by a magnetic emitter can be regarded as a large equivalent magnetic dipole. The near-field overlapping between this equivalent magnetic dipole and edge state enables achieving a cascade enhancement of single-photon emission with a Purcell factor exceeding 4 × 10