Wu Hanshuo, Li Ruixian, Xiao Hu, Huang Liangjin, Yang Huan, Pan Zhiyong, Leng Jinyong, Zhou Pu
Opt Express. 2021 Sep 27;29(20):31337-31347. doi: 10.1364/OE.435829.
The high absorption confined-doped ytterbium fiber with 40/250 μm core/inner-cladding diameter is proposed and fabricated, where the relative doping ratio of 0.75 is selected according to the simulation analysis. By employing this fiber in a tandem-pumped fiber amplifier, an output power of 6.2 kW with an optical-to-optical efficiency of ∼82.22% is realized. Benefiting from the large-mode-area confined-doped fiber design, the beam quality of the output laser is well maintained during the power scaling process with the beam quality factor of ∼1.7 of the seed laser to ∼ 1.89 at the output power of 5.07 kW, and the signal-to-noise ratio of the output spectrum reaches ∼40 dB under the maximum output power. In the fiber amplifier based on the 40/250 μm fully-doped ytterbium fiber, the beam quality factor constantly degrades with the increasing output power, reaching 2.56 at 2.45 kW. Moreover, the transverse mode instability threshold of the confined-doped fiber amplifier is ∼4.74 kW, which is improved by ∼170% compared with its fully-doped fiber amplifier counterpart.
提出并制备了芯径/内包层直径为40/250μm的高吸收受限掺杂镱光纤，根据模拟分析选择了0.75的相对掺杂比。通过将这种光纤应用于级联泵浦光纤放大器，实现了6.2kW的输出功率，光光效率约为82.22%。受益于大模面积受限掺杂光纤设计，输出激光的光束质量在功率放大过程中得到良好保持，种子激光的光束质量因子约为1.7，在5.07kW输出功率时达到约1.89，在最大输出功率下输出光谱的信噪比达到约40dB。在基于40/250μm全掺杂镱光纤的光纤放大器中，光束质量因子随输出功率增加而不断恶化，在2.45kW时达到2.56。此外，受限掺杂光纤放大器的横向模式不稳定性阈值约为4.74kW，与其全掺杂光纤放大器相比提高了约170%。
