Wu Hanshuo, Song Jiaxin, Ma Pengfei, Liu Wei, Ren Shuai, Wang Guangjian, Li Ruixian, Xiao Hu, Huang Liangjin, Leng Jinyong, Pan Zhiyong, Zhou Pu
Opt Express. 2022 Jun 6;30(12):21338-21348. doi: 10.1364/OE.459850.
In this work, a bidirectional tandem-pumped high-power narrow-linewidth confined-doped ytterbium fiber amplifier is demonstrated based on side-coupled combiners. Benefiting from the large-mode-area design of the confined-doped fiber, the nonlinear effects, including stimulated Raman (SRS) and stimulated Brillouin scattering (SBS), are effectively suppressed. While the transverse mode instability (TMI) effect is also mitigated through the combination of confined-doped fiber design and the bidirectional tandem pumping scheme. As a result, narrow-linewidth fiber laser with 5.96 kW output power is obtained, the slope efficiency and the 3-dB linewidth of which are ∼81.7% and 0.42 nm, respectively. The beam quality is well maintained during the power scaling process, being around M= 1.6 before the TMI occurs, and is well kept (M= 2.0 at 5.96 kW) even after the onset of TMI. No SRS or SBS is observed at the maximum output power, and the signal-to-noise ratio reaches as high as ∼61.4 dB. To the best of our knowledge, this is the record power ever reported in narrow-linewidth fiber lasers. This work could provide a good reference for realizing high-power high-brightness narrow-linewidth fiber lasers.
在这项工作中，基于侧面耦合器展示了一种双向串联泵浦的高功率窄线宽受限掺杂镱光纤放大器。受益于受限掺杂光纤的大模场面积设计，包括受激拉曼散射（SRS）和受激布里渊散射（SBS）在内的非线性效应得到有效抑制。同时，通过受限掺杂光纤设计与双向串联泵浦方案的结合，横向模式不稳定性（TMI）效应也得到缓解。结果，获得了输出功率为5.96 kW的窄线宽光纤激光器，其斜率效率和3 dB线宽分别约为81.7%和0.42 nm。在功率缩放过程中光束质量得到良好保持，在TMI出现之前约为M = 1.6，即使在TMI出现之后也能良好保持（在5.96 kW时M = 2.0）。在最大输出功率下未观察到SRS或SBS，信噪比高达约61.4 dB。据我们所知，这是窄线宽光纤激光器中报道的最高功率记录。这项工作可为实现高功率高亮度窄线宽光纤激光器提供良好参考。
