Fiber ring resonator with nanofiber section for chiral cavity quantum electrodynamics and multimode strong coupling

TL;DR

This paper reports the development of an optical fiber ring resonator with a nanofiber section that enables strong coupling with emitters and potential applications in chiral quantum optics and multimode quantum experiments.

Contribution

The authors experimentally realize a fiber ring resonator with a nanofiber section, demonstrating adjustable parameters and strong coupling regime suitability for quantum optics applications.

Findings

Achieved an unloaded finesse of 75+/-1 with low losses.

Enabled efficient interfacing with optical emitters via evanescent fields.

Potential for multimode strong coupling and chiral quantum optics applications.

Abstract

We experimentally realize an optical fiber ring resonator that includes a tapered section with subwavelength-diameter waist. In this section, the guided light exhibits a significant evanescent field which allows for efficient interfacing with optical emitters. A commercial tunable fiber beam splitter provides simple and robust coupling to the resonator. Key parameters of the resonator such as its out-coupling rate, free spectral range, and birefringence can be adjusted. Thanks to the low taper- and coupling-losses, the resonator exhibits an unloaded finesse of F=75+/-1, sufficient for reaching the regime of strong coupling for emitters placed in the evanescent field. The system is ideally suited for trapping ensembles of laser-cooled atoms along the nanofiber section. Based on measured parameters, we estimate that the system can serve as a platform for optical multimode strong coupling experiments. Finally, we discuss the possibilities of using the resonator for applications based on chiral quantum optics.