Mode-locked laser can produce stably a pulse train with a broadband spectrum to facilitate a precision frequency metrology. In contrast, with an overdrive in a cavity, an oscillator operates a chaotic, and noise-like pulse although seemingly regular pulse train. Furthermore, a conventional spectrometer, which consists of grating and line sensor, would be difficult to distinguish between mode-locked operation and noise-like pulse. Thanks to the single-shot spectrum measurement of a photonic time stretch spectroscopy  , the shot-to-shot spectrum is enabling to capture with long record length in real time. With this single shot spectral measurement, a dissipative soliton, soliton molecule, soliton rain, and optical rogue wave, was observed recently.
© 2019 Japan Society of Applied Physics, The Optical Society (OSA)PDF Article