Spatiotemporal dissipation dynamics: a route to high-beam-quality and high-peak-power spatiotemporal mode-locked fiber lasers

Spatiotemporal mode-locking (STML) opens a new avenue for implementing high-energy, high-peak-power modelocked fiber oscillators.However, the compromised beam quality poses a critical limitation to their broader applications. This study presents a method for enhancing the beam quality of STML fiber lasers by employing spatiotemporal dissipation involving the quenching and reabsorption effects of multimode erbium-doped fibers. The proposed technique introduces spatiotemporal saturable absorption, achieving high beam quality without the stringent conditions required for Kerr beam self-cleaning (BSC). Integrating spatiotemporal dissipation with Kerr BSC, we demonstrate an allanomalous- dispersion Er-doped STML fiber laser, which produces solitons with 6.7 nJ pulse energy (the intracavity solitons with 25.8 nJ pulse energy and >52.8 kW peak power), sub-500 fs pulse duration, and beam quality with M2x =M2y=1.23=1.20. To our knowledge, it is a record peak power for 1.5  m band soliton lasers. Additionally, the approach enables the generation of noise-like pulses with M2x =M2y=1.04=1.13. This work not only advances our understanding of spatiotemporal dissipation dynamics in STML fiber lasers, but also paves the way toward high-performance STML fiber lasers, rendering them very attractive for applications.