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High-order solitons exhibit fascinating dynamics during their propagation in anomalous dispersion media. High-order soliton dynamics have been intensively exploited for extreme pulse compression and coherent ultra-broadband spectrum generation. Despite recent advances, most previous studies have been restricted to soliton propagation external to a laser cavity, leaving the intracavity generation and evolution of high-order solitons less explored. Here, we numerically demonstrate that by carefully optimizing the cavity parameters, intracavity coherent supercontinuum could be generated via high-order soliton dynamics in a dissipative soliton fiber laser. In particular, a positively chirped dissipative soliton is formed in normal dispersion gain fiber, which acts as a robust nonlinear attractor. After dechirping, a high (∼8.5) order soliton was formed in a 1.1 m highly nonlinear fiber, which subsequently experienced significant intracavity temporal self-compression and spectral broadening. The shortest pulse duration was ∼14 fs, corresponding to ∼2.7 optical cycles at 1551 nm, with the spectrum spanning over 600 nm at the -30 dB level. The generated supercontinuum maintains high coherence under quantum noise injection. In addition, the supercontinuum bandwidths were further optimized via a genetic algorithm, demonstrating the great promise of machine learning tools in optimizing complicated nonlinear systems. This work opens new possibilities for constructing compact and highly coherent supercontinuum light sources. Additionally, it provides valuable insights into the self-consistent evolution dynamics of high-order solitons within a fiber laser cavity.
Tian et al. (Sun,) studied this question.