Geodesic photon coupling and non-Hermitian exceptional point of microcavities on topologically curved space

TL;DR

This paper introduces topologically curved microcavities supporting Whispering-gallery modes, demonstrating how space curvature enhances quality factors, enables mode coupling, and reveals non-Hermitian exceptional points, opening new avenues in geodesic microcavity photonics.

Contribution

It defines asymmetric microcavities on curved surfaces, showing how curvature improves quality factors and enables mode coupling and exceptional point observation.

Findings

Quality factors increased by up to ~200 times due to curvature

Strong and weak mode coupling occurs at resonance

Exceptional point observed at specific loss conditions

Abstract

Asymmetric microcavities supporting Whispering-gallery modes (WGMs) are of great significance for on-chip optical information processing. We define asymmetric microcavities on topologically curved surfaces, where the geodesic light trajectories completely reconstruct the cavity mode features. The quality factors of the lossy chaotic and island modes in flat cavities can be increased by up to ~200 times by the space curvature. Strong and weak coupling between modes of very different origins occur when the space curvature brings them into resonance, leading to a fine tailoring of the cavity photon energy and lifetime. Finally, we prove that by varying the overall loss, an exceptional point can be clearly observed at which both the cavity photon energy and lifetime become degenerate. Our work is at the crosspoint of optical chaotic dynamics, non-Hermitian physics and geodesic optical devices, and would open the novel area of geodesic microcavity photonics.