In this work, the transverse mode instability (TMI) behaviors in high-power all-fiber laser oscillators based on the ytterbium (Yb)-doped fiber (YDF) with a core diameter of 30 μ m have been experimentally investigated for the first time. We have constructed all-fiber laser oscillators with the YDF with core/inner-cladding diameter of 30/400 μ m and 30/600 μ m, and investigated the corresponding TMI thresholds respectively. Experimental results manifest that the YDF with the larger cladding diameter corresponds to a higher TMI threshold for the two types of YDF with 30 μ m core diameter. Compared with the 30/400 μ m fiber, the 30/600 μ m fiber can improve the TMI threshold by 2.0 times in the co-pumping configuration. By adopting bidirectional pumping configuration in the 30/600 μ m fiber oscillator, a maximum output power is scaled to ∼ 3.6 kW without any sign of TMI, and no Raman Stokes light is observed in the output spectra. To the b...

中文翻译：

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通过抑制横向模式不稳定性来改善具有30μm芯掺Yb光纤的全光纤激光振荡器的功率

在这项工作中，首次实验研究了基于掺有（（Yb）的光纤（YDF）和纤芯直径为30μm的高功率全光纤激光振荡器中的横模不稳定性（TMI）行为。 。我们用YDF构造了全光纤激光振荡器，其芯/内包层直径分别为30/400μm和30/600μm，并分别研究了相应的TMI阈值。实验结果表明，对于直径为30μm的两种YDF，包层直径较大的YDF对应较高的TMI阈值。与30/400μm光纤相比，在共同泵浦配置中，30/600μm光纤可以将TMI阈值提高2.0倍。通过在30/600μm光纤振荡器中采用双向泵浦配置，最大输出功率可缩放至〜3。6 kW无TMI迹象，在输出光谱中未观察到拉曼斯托克斯光。到...