# A medium-finesse optical cavity for the stabilization of Rydberg lasers

## TL;DR

This paper presents a medium-finesse optical cavity designed to stabilize lasers at 960 and 780 nm for ultracold rubidium Rydberg atom experiments, achieving linewidths below 10 kHz and minimal frequency drift.

## Contribution

The paper introduces a cost-effective, robust, and easy-to-construct optical cavity with active temperature stabilization for dual-laser frequency stabilization in Rydberg atom research.

## Key findings

- Laser linewidths reduced below 10 kHz
- Residual frequency drift limited to 1 MHz/day
- Cavity design optimized for robustness and affordability

## Abstract

We describe the design, construction, and characterization of a medium-finesse Fabry-P\'erot cavity for simultaneous frequency stabilization of two lasers operating at 960 and 780 nm wavelengths, respectively. The lasers are applied in experiments with ultracold rubidium Rydberg atoms, for which a combined laser linewidth similar to the natural Rydberg linewidth (approximately 10 kHz) is desired. The cavity, with a finesse of approximately 1500, is used to reduce the linewidth of the lasers to below this level. By using a spacer made of ultra low expansion (ULE) glass with active temperature stabilization, the residual frequency drift is limited to 1 MHz/day. The design optimizes for ease of construction, robustness, and affordability.