Pure high-even-order dispersion solitons in multimode mode-locked fiber lasers

Temporal solitons arise from the balance of dispersion and nonlinearity. Recent advances have extended beyond conventional second-order dispersion solitons, demonstrating that pure high-even-order dispersion solitons (PHEODSs), which emerge from the interplay of negative even-order dispersion and nonlinearity, possess superior energy-scaling capabilities. Multimode fiber lasers, with their rich spatiotemporal degrees of freedom, provide an ideal platform for investigating PHEODS dynamics. In this work, we numerically characterize the properties and diverse nonlinear phenomena of PHEODSs in multimode fiber lasers. We demonstrate bi-stability in a multimode cavity and uncover a direct transition to chaos via soliton explosion, bypassing conventional intermediate pulsating states. Furthermore, we identify a novel pulsating regime that simultaneously exhibits chaotic dynamics and dual-period pulsation, revealing a distinct instability pathway for PHEODSs. These insights deepen the understanding of novel dynamical evolution of PHEODS under non-equilibrium conditions. • Research highlight 1: First observation of direct chaos transition via soliton explosion in multimode fiber lasers, bypassing pulsating states. • Research highlight 2: Novel pulsating soliton regime with chaotic dynamics and dual-period pulsation in pure-high-even-order dispersion systems. • Research highlight 3: Pure-high-even-order-dispersion multimode fiber lasers provide a versatile platform for diverse nonlinear phenomena.