Figure 3.

Geometrical profile of the four ball resonators reported in this work. (a–d) Ball lens profilometry reporting the diameter on the horizontal and vertical axes (x, y) for each position (z) along the fiber axis, as estimated by the fiber measurement tool of the splicer. The chart reports the maximum diameter size and the ellipticity coefficient e. (e,f) Three-dimensional reconstruction of each ball resonator, expanding the profilometry data on each z plane. Resonator diameters: (a,e) 547 μm; (b,f) 532 μm; (c,g) 494 μm; (d,h) 466 μm.