Spectral-temporal dynamics of multipulse mode-locking

In addition to stable pulse generation, passively mode-locked fiber lasers can easily run into an unstable regime of multipulse mode-locking. The birth and dynamic behaviors of multipulse mode-locking so far have rarely been experimentally explored, particularly in the spectral domain. In this letter, several kinds of multipulse spectral-temporal dynamics of a passively mode-locked fiber laser are observed in a single-shot manner, e.g., energy quantization, self-phase modulation spectral broadening, wavelength shifting, spectral interfering, and ultraweak pulse interaction. This study is enabled by the high temporal resolution of spectral-temporal technology, i.e., 50 ps in the time domain and tens of nanoseconds in the spectral domain. Moreover, a wide observing time span of our spectral-temporal analyzing system, i.e.,>6ms-equivalent to 100 000 round trips, enables evolutionary characterization of individual pulses. The results will have a significant impact on optimizing the performance of mode-locked fiber lasers and understanding the nonlinear physics in a dissipative system. Published by AIP Publishing.