Kellert Martin, Demirbas Umit, Thesinga Jelto, Reuter Simon, Pergament Mikhail, Kärtner Franz X
Opt Express. 2021 Apr 12;29(8):11674-11682. doi: 10.1364/OE.422526.
We present record continuous wave (cw) output power levels from cryogenically cooled Yb:YLiF (Yb:YLF) lasers in rod geometry. The laser system is pumped by a state-of-the-art 960 nm diode module, and vertically polarized lasing was employed using the E//c axis of Yb:YLF. Lasing performance was investigated at different output coupling levels in different cavity configurations and the laser crystal temperature was estimated via monitoring the emission spectrum of the gain media. We have obtained a cw output power up to 400 W at a wavelength of 995 nm. The absorbed pump power was around 720 W, and the laser output had a TEM beam profile with an M of 1.3 in both axes. At higher absorbed pump power levels with increasing laser crystal temperature, we observed a lasing wavelength shift from 995 nm to 1019 nm. In this regime cw output power levels above 500 W have been achieved at an absorbed pump power of 750 W. Further power scaling was limited by the onset of strong thermal lensing. We discuss underlying physical mechanisms for the wavelength shift and present detailed temperature measurements under lasing conditions.
我们展示了棒状几何结构的低温冷却Yb:YLiF（Yb:YLF）激光器创纪录的连续波（cw）输出功率水平。该激光系统由最先进的960 nm二极管模块泵浦，并利用Yb:YLF的E//c轴实现垂直偏振激光发射。在不同的腔配置下，研究了不同输出耦合水平下的激光性能，并通过监测增益介质的发射光谱来估算激光晶体温度。我们在995 nm波长处获得了高达400 W的连续波输出功率。吸收的泵浦功率约为720 W，激光输出具有TEM光束轮廓，在两个轴上的M²为1.3。在吸收泵浦功率较高且激光晶体温度升高的情况下，我们观察到激光波长从995 nm移至1019 nm。在此状态下，在750 W的吸收泵浦功率下实现了超过500 W的连续波输出功率水平。进一步的功率缩放受到强热透镜效应出现的限制。我们讨论了波长偏移的潜在物理机制，并展示了激光条件下的详细温度测量结果。
