Ultra-stable open micro-cavity platform for closed cycle cryostats

Open-access micro-cavities are a powerful tool for enhancing light-matter interactions for solid-state quantum and nano systems and are key to advance applications in quantum technologies. In order to achieve good coherence properties of the material, most of them have to be cooled down to cryogenic temperatures. In addition, the use of external magnetic fields is required for many emitter classes to fine-tune optical transitions. Here, we present the integration of a fully-tunable, open-access, fiber-based Fabry-Pérot micro-cavity platform into the vibrational environments of different closed-cycle cryostats reaching sub-pm mechanical stability. In addition, we show the development of superconducting coils to generate fields up to 150 mT for those cryogenic cavity scenarios.