Transverse mode instability (TMI) is one of the main limitations for the power scaling of high-power fiber lasers. In order to suppress TMI and increase the output power of the fiber laser, we demonstrated a novel strategy by shifting the center wavelength of the pump source, i.e., laser diodes (LDs), from conventional 976 nm to the optimized 981 nm. A fiber oscillator is built to investigate the TMI effect in different pump wavelengths. Compared with 976 nm LDs, the TMI threshold increases from 208 W to 448 W when the laser is pumped by 981 nm LDs, indicating a 2.2 times enhancement of the TMI threshold. We also simulated and analyzed that the main heat source leading to TMI effect is the thermal effect caused by pump absorption, followed by quantum defect. We believe the optimized pump source has potential applications for suppressing TMI and in the power scaling of both broadband and narrow linewidth fiber lasers.

中文翻译：

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通过优化泵浦波长提高掺镱光纤激光器的TMI阈值


横模不稳定性（TMI）是高功率光纤激光器功率缩放的主要限制之一。为了抑制TMI并提高光纤激光器的输出功率，我们展示了一种新颖的策略，将泵浦源（即激光二极管（LD））的中心波长从传统的976 nm转移到优化的981 nm。构建光纤振荡器是为了研究不同泵浦波长下的 TMI 效应。与976 nm LD相比，当激光被981 nm LD泵浦时，TMI阈值从208 W增加到448 W，表明TMI阈值提高了2.2倍。我们还模拟分析了导致TMI效应的主要热源是泵浦吸收引起的热效应，其次是量子缺陷。我们相信优化的泵浦源在抑制 TMI 以及宽带和窄线宽光纤激光器的功率缩放方面具有潜在的应用。