Fig. 1. Principle of the ultrafast pulse-stimulated UHRP. T₀, period of the seed pulse; F, repetition rate of the seed pulse; F_s, repetition rate of the UHRP; F_F and T, repetition rate and period of the dissipative cavity.

Fig. 2. Experimental setup of the UHRP fiber ring cavity. DCF, dispersion-compensating fiber; EYDFA, erbium-ytterbium co-doped amplifier; OC, output coupler; FROG, frequency-resolved optical gating; OSA, optical spectrum analyzer.

Fig. 3. Characteristics of the seed pulse and MZI filter. (a) Spectra of the ultrafast pulse at Point A; (b) FROG trace of the seed pulse (inset, autocorrelation trace); (c) transmission curve and (d) FROG trace of the pulse at Point B.

Fig. 4. Ultrafast pulse-stimulated UHRPs. (a) The spectra at different seed pulse powers; (b) the spectrum of the UHRP when the ultrafast seed pulse is switched off (see the Visualization 1); (c) the recording of UHRP spectra every 5 min, with corresponding parts (d) detailing the FROG and the autocorrelation trace, respectively.

Fig. 5. Diagram of the ultrafast pulse-stimulated UHRP. (a) Spectra when the seed pulses are ON (in blue) and OFF (in red), respectively; (b) presentation of the corresponding temporal characterization through FROG trace analysis.

Fig. 6. Simulation model of the ultrafast pulse-stimulated UHRP fiber laser. SMF, single-mode fiber; OC, optical coupler.

Fig. 7. Spectra and temporal pulses at different cavity locations: (a) and (b) seed pulses; (c) and (d) pulses after the comb filter.

Fig. 8. Characteristics of the pulse evolution: (a) UHRP spectrum; (b) pulse evolution in the frequency domain; (c) pulse evolution in the time domain (Insets illustrate three steps from the split state to the UHRP state); (d) energy evolution (The inset shows energy oscillation).

Fig. 9. Relationship of the rates between MZI spacing and the cavity fundamental rate.