A Chaotic State in the Transition From Single Toward Multiple Pulse for Soliton Fiber Lasers

High-order soliton in anomalous-dispersion ultrafast fiber lasers is rarely researched due to its intrinsic instability in dissipative systems. For the first time, we numerically demonstrate the ultrafast pulse in fiber lasers will deviate from the fundamental soliton under strong pulse energy before splitting into multiple pulses. High-order soliton effect results in the single-pulse splitting into the dual-pulse. Sustaining switching between the single- and dual-pulse induced by the high-order soliton evolution and cross-gain-modulation was observed and analyzed. The results offer significant and novel insights for the soliton shaping dynamics and instability in anomalous-dispersion fiber lasers.