A tunable fiber Fabry-Perot cavity for hybrid optomechanics stabilized at 4 K

TL;DR

This paper presents a highly tunable and stable fiber Fabry-Perot cavity system operating at 4 K, enabling hybrid optomechanical experiments with precise control and minimal drift.

Contribution

It introduces a fiber-based Fabry-Perot cavity platform with enhanced tunability and stability at cryogenic temperatures for hybrid optomechanics.

Findings

Cavity length stability better than a few picometers over hours

Successful operation at 4 K with high finesse

Precise positioning of mechanical resonator within the cavity

Abstract

We describe an apparatus for the implementation of hybrid optomechanical systems at 4 K. The platform is based on a high-finesse, micrometer-scale fiber Fabry-Perot cavity, which can be widely tuned using piezoelectric positioners. A mechanical resonator can be positioned within the cavity in the object-in-the-middle configuration by a second set of positioners. A high level of stability is achieved without sacrificing either performance or tunability, through the combination of a stiff mechanical design, passive vibration isolation, and an active Pound-Drever-Hall feedback lock incorporating a reconfigurable digital filter. The stability of the cavity length is demonstrated to be better than a few picometers over many hours both at room temperature and at 4 K.