Laser written mirror profiles for open-access fiber Fabry-P\'erot microcavities

TL;DR

This paper presents a method for creating laser-written mirror profiles on optical fiber endfaces, enabling tunable microcavities with high finesse and stability, suitable for advanced optical experiments.

Contribution

The authors demonstrate a novel laser-writing technique for fabricating flexible, high-performance mirror profiles on fiber endfaces for open-access microcavities.

Findings

Achieved finesse up to 250 with stable performance.

Reached a peak quality factor of 1.5×10^4 near stability limit.

Cavity mode waist of 2.3 μm and Purcell factor of 2.5.

Abstract

We demonstrate laser-written concave hemispherical structures produced on the endfacets of optical fibers that serve as mirror substrates for tunable open-access microcavities. We achieve finesse values of up to 250, and a mostly constant performance across the entire stability range. This enables cavity operation also close to the stability limit, where a peak quality factor of $1.5\times 10^4$ is reached. Together with a small mode waist of $2.3\; \mathrm{\mu m}$, the cavity achieves a Purcell factor of $C \sim 2.5$, which is useful for experiments that require good lateral optical access or otherwise large separation of the mirrors. Laser-written mirror profiles can be produced with a tremendous flexibility in shape and on various surfaces, opening new possibilities for microcavities.