A mechanically stable and tunable cryogenic Fabry-Pérot microcavity.

Area of Science:

• Quantum Optics and Quantum Information Science
• Optomechanical Systems
• Nanophotonics

Background:

• High-finesse microcavities are crucial for enhancing photon-matter interactions in quantum applications.
• Mechanical vibrations in closed-cycle cryostats limit the performance of tunable, open-geometry microcavities requiring spatial control and free-space access.

Purpose of the Study:

• To design and characterize a vibration-isolated system for high-finesse microcavities within a closed-cycle cryostat.
• To enable stable, tunable cavity operation with spatial positioning and free-space optical access for quantum experiments.

Main Methods:

• Developed a system with two cascaded vibration isolation stages using leaf springs to decouple motion.
• Incorporated tuned-mass and magnetic damping to minimize mechanical vibrations (achieving ~16 pm-rms stability).
• Implemented a technique for in situ measurement of cavity length displacements and vibrations.

Main Results:

• Achieved passive mechanical stability of ~16 pm-rms for high-finesse mirrors.
• Demonstrated three-dimensional positioning of the cavity mode and free-space confocal imaging capability.
• Successfully quantified cavity length displacements and vibrations, with and without active feedback.

Conclusions:

• The developed system enables stable operation of tunable, high-finesse microcavities within closed-cycle cryostats.
• This technology is an enabler for cavity coupling to diverse solid-state quantum systems.
• Facilitates advancements in quantum optics and quantum information science applications.