Single-shot characterization of special multi-soliton and noise-like pulse emissions in a mode-locked fiber laser

Single-shot characterization of three categories of multi-pulse emissions in a passively mode-locked fiber laser based on nonlinear polarization rotation is experimentally reported. The mechanism to control the intracavity polarization state relies on a polarizer beam splitter cube together with a half-wave and a quarter-wave retarders. With a precise adjustment of the retarders, the fiber laser can reach different mode locking regimes involving noise-like pulses (NLP) and solitons. These regimes include (i) NLP emission exhibiting broad-bandwidth supercontinuum spectrum, (ii) multiple soliton emission in the form of soliton bunches with rectangular-shaped envelope, and (iii) NLP emission with complex pulse patterns, such as the one obtained from the breakup of a rectangular NLP, or the harmonic mode locking regime exhibiting multiple, uniformly spaced NLP wave packets. The experimental results presented in this work provide useful information for a better understanding of different types of multi-pulse emission from the same fiber laser system, complementing the studies focused on the nature and physical mechanisms underlying NLP emission.

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