Fig. 1. (a) Photographs of the five micro-rod resonators fabricated on a single silica rod preform and the microscopy images of two resonators (2 and 4). (b) The FSRs and the FSR variation between every two resonators fabricated successively. (c) The Q-factors of the five fabricated resonators.

Fig. 2. (a)–(c) Transmission spectra of the resonator fabricated initially, annealed once, and annealed four times iteratively. The spectral peaks of the target modes are marked by black solid rectangles. The arrow lines mark the FSRs of the target modes. (d)–(f) Expanded plots of the spectral peaks of target modes, marked by black solid rectangles in (a)–(c). (g) The FSRs and the FSR variations vary with the number of iterative annealing processes. The dotted line represents the average value of FSR variation. (h) The Q-factor varies with the number of iterative annealing processes.

Fig. 3. Average FSR variation and average Q-factor vary with annealing time.

Fig. 4. (a) Experimental setup of single-DKS microcomb generation via auxiliary laser heating in micro-rod resonator. CW, continuous-wave narrow linewidth tunable fiber laser; AOM, acoustic optical modulator; EDFA, erbium-doped fiber amplifier; FPC, fiber polarization controller; FBG, fiber Bragg grating; PM, power measuring instrument; ESA, electrical spectrum analyzer; OSA, optical spectrum analyzer. (b)–(d) Optical spectra of the three single-DKS microcombs generated with a micro-rod resonator fabricated initially, annealed once, and annealed twice iteratively with 20 s annealing time. (e) RF beat note spectra of three single-DKS microcombs shown in (b)–(d).