Lou Zhaokai, Yang Baolai, Han Kai, Wang Xiaolin, Zhang Hanwei, Xi Xiaoming, Liu Zejin
College of Advanced Interdisciplinary Studies, National University of Defense Technology, Changsha, 410073, China.
Hunan Provincial Key Laboratory of High Energy Laser Technology, Changsha, Hunan, 410073, China.
Sci Rep. 2020 Jun 2;10(1):9006. doi: 10.1038/s41598-020-66470-3.
In this manuscript, we studied the thermal properties of hundred-watt fiber laser oscillator by real-time in-situ distributed temperature measurement. Optical frequency domain reflectometry (OFDR) was introduced to measure the temperature distribution of gain fiber core. The fiber laser oscillator operated at 1080 nm and the wavelength of detecting signal from OFDR was ~1550 nm. The maximum output power of this fiber oscillator was 100 W. The fiber core temperature distributions in experiment agree well with our theoretical simulation. The temperature measurement of gain fiber core in oscillator has always been a problem because the backward laser from the oscillator may reduce the signal-to-noise ratio in OFDR. To the best of our knowledge, this is the first temperature distribution measurement of fiber core in hundred-watt oscillator. By the experimental measurement and theoretical model, we also analyzed the thermal properties of laser oscillator respectively pumped by 915 nm and 976 nm LD sources. We found fiber laser oscillator pumped by 976 nm LD sources experienced not only higher maximum thermal load but also higher average thermal load than that pumped by 915 nm LD sources at the same level output power. We also analyzed the fiber core temperature of other components in system, such as combiners and fiber Bragg gratings (FBG). These results are meaningful for us to improve the thermal design and management in fiber lasers.
在本论文中，我们通过实时原位分布式温度测量研究了百瓦级光纤激光振荡器的热特性。引入了光频域反射仪（OFDR）来测量增益光纤纤芯的温度分布。该光纤激光振荡器工作在1080nm波长，OFDR检测信号的波长约为1550nm。此光纤振荡器的最大输出功率为100W。实验中的光纤纤芯温度分布与我们的理论模拟结果吻合良好。振荡器中增益光纤纤芯的温度测量一直是个问题，因为振荡器的后向激光可能会降低OFDR中的信噪比。据我们所知，这是首次对百瓦级振荡器中的光纤纤芯进行温度分布测量。通过实验测量和理论模型，我们还分别分析了由915nm和976nm激光二极管（LD）源泵浦的激光振荡器的热特性。我们发现，在相同输出功率水平下，由976nm LD源泵浦的光纤激光振荡器不仅承受的最大热负载更高，而且平均热负载也比由915nm LD源泵浦的更高。我们还分析了系统中其他部件的光纤纤芯温度，如合束器和光纤布拉格光栅（FBG）。这些结果对我们改进光纤激光器的热设计和热管理具有重要意义。
