High Power Laser Science and Engineering, Vol. 9, Issue 1, 010000e8 (2021)
Up conversion and excited state absorption analysis in the Tm:YAG disk laser multi-pass pumped by 1 μm laser
Enmao Song1,2, Guangzhi Zhu1,2,*, Hailin Wang1,2, Hantian Chen1,2, Yefeng Qian1,2, Kozlov Aleksei3, and Xiao Zhu1,2
- 1School of Optical and Electronic Information, Huazhong University of Science andTechnology, Wuhan430074, China
- 2National Engineering Research Center for Laser Processing, Wuhan430074, China
- 3POLYUS Research Institute of M.F. Stelmakh Joint Stock Company, Moscow117342, Russia
We present a 2 μm Tm:YAG disk laser multi-pass pumped by a 1 μm laser. The transitions in competition of up conversion (UC) and excited state absorption (ESA) are analyzed in detail based on a numerical model that considers stimulated emission, fluorescence, non-radiative decay, UC, andESA, showing good agreement with experiments. The proportions and fractional thermal loads of all transitions are derived quantitatively. The results show that UC and ESA are critical in Tm:YAG disk lasers, resulting in a decrease in the absorbed pump power and temperature after lasing for two different disk thicknesses. In addition, although the absorbed pump power of the 0.5 mm disk is lower than in the 1 mm case, its relatively weak UC and ESA and low total fractional thermal load can improve laser performance. A 0.5 mm Tm:YAG disk laser thus delivered the maximum output power of1.05 W with beam quality of Mx2 = 2.02 and My2 = 2.03.
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