Fig. 1. Experimental setup of CO₂ laser ablation system and surface profiler for the fabrication of fiber cavity mirrors.

Fig. 2. (a) Contour plot of the concave fiber cavity mirror. The horizontal gray dashed line is the baseline of the mirror orientation (θ = 0°), and the θ stands for the relative angle of different mirror orientations for cross sections around the mirror center. (b) Cross section of the concave fiber cavity mirror fitted by a circular equation. (c) Difference between the measured Z data and the fitting Z data on the scale of the 744 nm working wavelength. (d) The distribution of ROC for mirror orientations fitted by an ellipsoid model, and the θ₀ stands for the relative angle of the mirror orientation at the major axis.

Fig. 3. Experimental setup of the high-precision alignment testing platform.

Fig. 4. (a) Transmission signal of optical fiber microcavity at the 744 nm working wavelength with the cavity length of 100 µm. (b) Transmission peaks of optical fiber microcavity consisting of two low-transmission (LT) cavity mirrors before annealing (black line) and after annealing (red line).

Fig. 5. (a) Assembly of the optical fiber microcavity consists of fiber cavity mirrors, V grooves, piezos, copper wires, spacers, and the baseplate. (b) Finesse change of the optical fiber microcavity tested in the ultra-high vacuum chamber at the 850 nm locking wavelength for 4 months. The fluctuation of the measured finesse results from the uncertainty of the measurement method.