基于主振荡功率放大（MOPA）结构，搭建了千瓦级掺Yb全光纤放大器。最大泵浦功率为1496 W的条件下，获得了1024 W波长1.08μm的基模连续激光输出，光－光转换效率68.5％，光束质量M2＝1.24。对高功率连续光纤放大器中的热效应进行研究，并对于仅由于涂覆层的热损伤引起的功率极限给出了理论模拟。不同散热条件下，对掺Yb光纤横截面上径向的温度分布进行了模拟。通过对20／390μm无源光纤与20／400μm掺Yb光纤的熔接方式进行优化，解决了模拟结果与实验结果不一致的问题，并对该点的冷却进行了实验研究。最终，放大级泵浦光注入处熔接点表面最大温度不超过60℃。%Based on the master oscillator power amplifier (MOPA)structure,a kilowatt level Yb-doped all-fiber laser with the output power of 1024 W and the wavelength of 1.08μm is obtained when the maximum pump power is 1496W,and the beam quality tested M2 is 1.24 and optical-optical conversion efficiency is 68.5%.The thermal effects for high power fiber lasers are studied,and the power limit of fiber lasers by the thermal degradation of coatings is theoretically simulated.The radial temperature distribution of fibers was simulated under different cooling condi-tions.To solve the problem that simulated results are inconsistent with experimental results,the fusion splicing method of 20/390 μm passive optical fiber and 20/400 μm Yb-doped fiber is optimized and the cooling technology is studied experimentally.The surface temperature at the pump light launching end splice of the booster amplifier is about 60℃.
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