泵浦线宽和波长飘移对全固态Tm激光器性能的影响

为了研究泵浦带宽和波长飘移对全固态激光器的影响，进行了光谱分析和热效应分析，该分析是在准三能级Tm:YAG激光器上进行的。提出光谱模型和晶体热模型，用来研究不同泵浦带宽下Tm激光器的效率和热效应。在Tm激光实验中，结构紧凑、高效率的键合Tm激光器得到验证，中心波长输出在2 013.2 nm。这一激光器的泵浦源是0.1 nm窄线宽的光纤耦合激光二极管，其输出波长是784.9 nm。最大输出功率为7.96 W，斜率效率为62.5%，光-光转换效率为53.3%。当耦合透过率为3%时，激光功率从1.87 W增大到14.93 W，激光波长从2 013.25~2 014.53 nm飘移。当耦合透过率为5%时，输出波长从2 013.91 nm飘移到2 014.26 nm。尽管晶体的最高温度会稍有上升，但0.1 nm窄带宽泵浦可以有效提高激发效率，因此具有更高的激光效率。通过综合考虑泵浦带宽和波长飘移以及增益介质的光谱分布，该研究可以扩展到其他固体激光器来选择泵浦源，有助于实现高效的激光系统。

Influence of pump bandwidth and wavelength-drift on laser performance of solid-state Tm laser

In order to study the influence of pump bandwidth and wavelength-drift on the performance of solid-state lasers, theoretical analyses were performed on a quasi-three-level Tm:YAG laser, and the corresponding theoretical models, including both spectral and thermal models, were presented. In the Tm laser experiment, a compact and high-efficiency composite Tm laser operating at 2 013.2 nm was demonstrated, which was end-pumped by volume Bragg gratings(VBGs) locked laser diode(LD) with emission wavelength centered at 784.9 nm and bandwidth as narrow as 0.1 nm(full width at the half maximum, FWHM). A maximum output power of 7.96 W was obtained with a slope efficiency of 62.5% and optical conversion efficiency of 53.3%, respectively. The maximum laser wavelength drifted from 2 013.25 nm to 2 014.53 nm when increasing the absorbed pump power from 1.87 W to 14.93 W for the 3% output coupling. As for 5% output coupling, the drift was from 2 013.91 nm to 2 014.26 nm. It was found that a narrow LD bandwidth of 0.1 nm resulted in a more pronounced excitation efficiency and thus a higher laser efficiency, despite that the maximum temperature within the crystal was slightly higher. The present study could be extended to other solid-state lasers for the choice of pump source by comprehensively considering the pump bandwidth and wavelength-drift and the spectral profiles of gain medium, which would be helpful for an efficient laser system.