Numerical study of mid-infrared pure quartic soliton fiber lasers

Pure-quartic solitons (PQSs), as an emerging branch of the soliton family, have flourished and achieved significant progress in near-infrared fiber laser systems. Extending their generation to the mid-infrared (mid-IR) region and revealing associated nonlinear dynamics are of great interest. Herein, we numerically investigate the generation and dynamic behaviors of mid-IR PQSs at 3 µm in a passively mode-locked Dy 3+ -doped fluoride fiber laser. The simulation results demonstrate that mid-IR PQSs, in contrast to their near-IR counterparts, can be generated under a negative fourth-order net cavity dispersion of significantly smaller magnitude (∣ β 4 ∣ L <4.5×10 −3 ps 4 ). Furthermore, under the fourth-order net cavity dispersion β 4 L =−1.8×10 −3 ps 4 , annihilation and crawling dynamics of mid-IR PQS molecules are observed by selecting the appropriate saturable energy of the Dy 3+ -doped fluoride fiber. These findings offer critical theoretical insights for the generation and manipulation of mid-IR PQS mode-locked fiber lasers.