A soliton explosion refers to a phenomena in passive mode locked lasers where spectral structure of the laser pulse disappear suddenly but returns back its original shape after a few roundtrips. This phenomena timescale is from nanoseconds to microseconds, and therefore this particular event of single-shot pulse spectrum cannot be detected by using a conventional spectrometer which consists on a grating and a linear array detector. Progress on photonic time-stretch is enabling the single-shot spectral measurement in real-time. Previous observations of soliton explosion in fiber lasers was limited to dissipative soliton in an operation state between mode locking and noise-like pulses. Here we report the first observation of soliton explosion in an unstable mode locking region in the stretched pulse configuration via nonlinear polarization evolution with time stretch spectroscopy. Developing with an Yb doped fiber laser and capturing 8000 consecutive single-shot spectra, we observed that the features of soliton explosion dynamics between narrow and broadband mode locking regimes. We anticipate that the explosion dynamics are related to a pulse energy decreasing process during the stabilizing toward the steady state mode locking operation. We believe that these results provide us novel insights into understanding the broadband spectral formation and evolution in unstable mode locking regime of lasers.
We have experimentally reported on a real-time single-shot spectroscopy of a broadband Yb-doped fiber (YDF) laser which based on a nonlinear polarization evolution by using a time-stretched dispersive Fourier transformation technique. We have measured an 8000 consecutive single-shot spectra of mode locking and noise-like pulse (NLP), because our developed broadband YDF oscillator can individually operate the mode locking and NLP by controlling a pump LD power and angle of waveplates. A shot-to-shot spectral fluctuation was observed in NLP. For the investigation of pulse formation dynamics, we have measured the spectral evolution in an initial fluctuations of mode locked broadband YDF laser at an intracavity dispersion of 1500 and 6200 fs<sup>2</sup> for the first time. In both case, a build-up time between cw and steady-state mode locking was estimated to be 50 us, the dynamics of spectral evolution between cw and mode locking, however, was completely different. A shot-to-shot strong spectral fluctuation, as can be seen in NLP spectra, was observed in the initial timescale of 20 us at the intracavity dispersion of 1500 fs<sup>2</sup>. These new findings would impact on understanding the birth of the broadband spectral formation in fiber laser oscillator.
Conference Committee Involvement (4)
Real-time Measurements, Rogue Phenomena, and Single-Shot Applications VI
23 January 2021 | San Francisco, California, United States
Real-time Measurements, Rogue Phenomena, and Single-Shot Applications V
4 February 2020 | San Francisco, California, United States
Real-time Measurements, Rogue Phenomena, and Single-Shot Applications IV
6 February 2019 | San Francisco, California, United States
Real-time Measurements, Rogue Phenomena, and Single-Shot Applications III
29 January 2018 | San Francisco, California, United States