Huang Yusheng, Yan Ping, Wang Zehui, Tian Jiading, Li Dan, Xiao Qirong, Gong Mali
Opt Express. 2019 Feb 4;27(3):3136-3145. doi: 10.1364/OE.27.003136.
In this paper, we demonstrated a monolithic fiber-Bragg-grating-based (FBG-based) master oscillator power amplification configuration fiber laser with a narrow linewidth at high-power level. Several approaches were implemented to reduce the seed laser linewidth and the magnification of spectrum broadening in order to achieve a narrow output linewidth. The narrow seed laser linewidth was obtained by restricting the reflection bandwidth of the FBG. To reduce the magnification of spectrum broadening, a backward pumping scheme was employed in the amplifier stage after its capacity to suppress laser spectrum broadening was preliminarily investigated experimentally. Further, by intentionally shortening the length of the active fiber in the amplifier and sharing the backward pumping power with the oscillator, the spectrum broadening was further inhibited without sacrificing optical efficiency. A maximum output power of 2.19 kW was achieved with a 3 dB spectrum bandwidth of only 86.5 pm. The beam quality at the maximum power was measured to be M~1.46. No sign of transverse mode instability was shown during the experiments.
在本文中，我们展示了一种基于单片光纤布拉格光栅（FBG）的主振荡功率放大结构光纤激光器，其在高功率水平下具有窄线宽。实施了几种方法来减小种子激光线宽和光谱展宽的放大倍数，以实现窄输出线宽。通过限制FBG的反射带宽获得了窄种子激光线宽。为了降低光谱展宽的放大倍数，在对放大器阶段抑制激光光谱展宽的能力进行初步实验研究后，采用了后向泵浦方案。此外，通过有意缩短放大器中有源光纤的长度并与振荡器共享后向泵浦功率，在不牺牲光效率的情况下进一步抑制了光谱展宽。实现了2.19 kW的最大输出功率，3 dB光谱带宽仅为86.5 pm。最大功率下的光束质量测量为M~1.46。实验过程中未出现横向模式不稳定性迹象。
