Tunable fiber Fabry-Perot cavities with high passive stability

We present three high finesse tunable monolithic fiber Fabry-Perot cavities (FFPCs) with high passive mechanical stability. The fiber mirrors are fixed inside slotted glass ferrules, which guarantee an inherent alignment of the resonators. An attached piezoelectric element enables fast tuning of the FFPC resonance frequency over the entire free-spectral range for two of the designs. Stable locking of the cavity resonance is achieved for sub-Hertz feedback bandwidths, demonstrating the high passive stability. At the other limit, locking bandwidths up to tens of kilohertz, close to the first mechanical resonance, can be obtained. The root-mean-square frequency fluctuations are suppressed down to similar to 2% of the cavity linewidth. Over a wide frequency range, the frequency noise is dominated by the thermal noise limit of the system's mechanical resonances. The demonstrated small footprint devices can be used advantageously in a broad range of applications like cavity-based sensing techniques, optical filters or quantum light-matter interfaces. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The study introduces three high finesse tunable monolithic fiber Fabry-Perot cavities with high passive mechanical stability, suitable for various applications such as cavity-based sensing techniques, optical filters, and quantum light-matter interfaces. The devices demonstrate stable locking of cavity resonance with sub-Hertz feedback bandwidths and suppression of root-mean-square frequency fluctuations to approximately 2% of the cavity linewidth. The frequency noise in a wide range is mainly limited by the thermal noise of the system's mechanical resonances.