High-cooperativity FP cavity with long cavity length.

We have developed a Fabry-Pérot optical cavity with a length of 1.67 mm, a cooperativity of 100, a waist radius of 9.6 μm, and an ultra-low residual reflection loss (1-R) of 32 ppm. To verify the coupling strength, we coupled the cavity with a single rubidium-87 (Rb₈₇) atom trapped in an optical tweezer in a vacuum environment, and completed the performance validation through the scanned spectrum.

A microscope module is retained in our system, and high-precision alignment between the microscope and the cavity is achieved via a scanning near-field optical microscopy (SNOM) fiber. Meanwhile, sufficient optical manipulation space is reserved by optimizing the cavity substrate configuration design, laying a solid foundation for subsequent diverse cavity quantum electrodynamics (CQED) research.