Open AccessSecond harmonic generation enhancement and directional emission from topological corner state based on the quantum spin Hall effect
Author(s) -
Kai Guo,
Jintao Wu,
Fujia Chen,
Keya Zhou,
Shutian Liu,
Zhongyi Guo
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.432660
Subject(s) - second harmonic generation , topology (electrical circuits) , physics , photon , photonics , quantum hall effect , quantum optics , photonic crystal , optics , geometric phase , condensed matter physics , quantum mechanics , electron , laser , mathematics , combinatorics
Topological corner state has attracted much research interests since it does not obey the conventional bulk-edge correspondence and enables tightly confined light within small volumes. In this work, we demonstrate an enhanced second harmonic generation (SHG) from a topological corner state and its directional emission. To this end, we design an all-dielectric topological photonic crystal based on optical quantum spin Hall effect. In this framework, pseudospin states of photons, topological phase, and topological corner state are subsequently constructed by engineering the structures. It is shown that a high Q-factor of 3.66×10 11 can be obtained at the corner state, showing strong confinement of light at the corner. Consequently, SHG is significantly boosted and manifests directional out-of-plane emission. More importantly, the enhanced SHG has robustness against a broad class of defects. These demonstrated properties offer practical advantages for integrated optical circuits.