We present a 2 μm Tm:YAG disk laser multi-pass pumped by 1 μm laser. The competition transitions of up conversion (UC) and excited state absorption (ESA) are analyzed in detail based on a numerical model accounting stimulated emission, fluorescence, non-radiative decay, UC and ESA, showing good agreement with experiment. 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 the absorbed pump power and temperature decreased after lasing for two different thickness of disk. In addition, although the absorbed pump power of 0.5 mm disk is lower than 1 mm case, its relatively weak UC and ESA and low total fractional thermal load can improve laser performances. A 0.5 mm Tm:YAG disk laser thus delivered the maximum output power of 1.05 W with beam quality of Mx2 = 2.02 and My2 = 2.03.
song enmao, Zhu Guangzhi, Wang Hailin, chen hantian, qian yefeng, Aleksei Kozlov, Zhu Xiao. Up conversion and excited state absorption analysis in the Tm:YAG disk laser multi-pass pumped by 1 μm laser[J]. High Power Laser Science and Engineering, , (): .
