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

Jia, Yali; Tian, Zhaohua; Liu, Qi; Mou, Zhengyang; Mo, Zihan; Tian, Yu; Gong, Qihuang; Gu, Ying · Nano Lett · 2024

basic_science · Level V

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Abstract

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<sup>3</sup>. These emitted photons are guided into edge states with a collection efficiency of more than 90%, which is also corresponding to quantum yield due to topological antiscattering and the absence of absorption. The proposed mechanism under topological protection has potential applications in on-chip light-matter interactions, quantum light sources, and nanolasers.