High-power Ho:YAG MOPA system pumped by a Tm-fiber laser with 269 W average output power at 10 kHz

A pulsed high-power and high-stability Ho:YAG master-oscillator power amplifier (MOPA) system, single-end pumped by Tm-doped fiber lasers, was designed and demonstrated. By considering the thermal lensing effect in the single-end pumped Ho:YAG amplifier, a suitable beam size was designed to avoid the crystal damage and achieve efficient and stable high-power laser output. The maximum average output power of the Ho:YAG MOPA system reached 269 W at a pulse repetition rate of 10 kHz and a pulse width of 20.5 ns, corresponding to the pulse energy and peak power of 26.9 mJ and 1.31 MW. Meanwhile, the stability of this MOPA system was excellent, with a root mean square deviation of 0.096% over 30 minutes at maximum output power. The extraction efficiency of the total amplifier system was 56.8%.