A high-power monolithic continuous wave (CW) Yb doped fiber amplifier at 1064 nm has been demonstrated based on traditional large mode area step-index fiber, which generated 5.07 kW narrow line-width laser with near diffraction-limited beam quality. At the maximal output power, >35dB OSNR has been achieved with line-width being 370pm, and the measured beam quality is M ² _x = 1.252, M ² _y = 1.322. The influence of cooling temperature on SRS has been investigated in high power fiber lasers, which shows that the SRS at 4kW has been suppressed 24 dB by lowering the temperature from 20°C to 8°C. To the best of our knowledge, this is the highest narrow line-width laser power generated from the traditional large mode area step-index monolithic fiber amplifier.

中文翻译：

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>5kW 记录来自传统阶跃折射率单片光纤放大器的高功率窄线宽激光器

基于传统的大模式面积阶跃折射率光纤，已经展示了一种 1064 nm 的高功率单片连续波 (CW) 掺镱光纤放大器，它产生了 5.07 kW 窄线宽激光器，光束质量接近衍射极限。在最大输出功率下，已实现 >35dB OSNR，线宽为 370pm，测量的光束质量为 M ² _x = 1.252，M ² _y = 1.322。在高功率光纤激光器中研究了冷却温度对 SRS 的影响，结果表明，通过将温度从 20°C 降低到 8°C，4kW 处的 SRS 被抑制了 24 dB。据我们所知，这是传统大模式面积阶跃折射率单片光纤放大器产生的最高窄线宽激光功率。