161 W middle infrared ZnGeP2 MOPA system pumped by 300 W-class Ho:YAG MOPA system

We demonstrated a high-power switched two-stage Ho:YAG master-oscillator power-amplifier (MOPA) system dual-end pumped by Tm:YLF lasers. A new method was introduced by rotating and swapping spatial axial directions of pump beams to improve the beam quality of the Ho:YAG oscillator and first-stage amplifier. Two parallel second-stage Ho:YAG amplifiers were employed to output high power. A total maximum average output power of 332 W at 2091 nm with pulse repetition frequency of 20 kHz was achieved. Then a ZnGeP2 MOPA system was demonstrated using the Ho:YAG MOPA as the pump source. A maximum average output power of 161 W at 3-5 mu m was obtained with 290 W incident Ho pump power, corresponding to beam quality factors M-2 of 3.42 and 3.83 for horizontal and vertical directions, respectively. (C) 2020 Optical Society of America

Automated summary

A high-power switched two-stage Ho:YAG MOPA system was demonstrated using Tm:YLF lasers. A new method was introduced to improve beam quality by rotating and swapping spatial axial directions of pump beams. High power output was achieved by employing two parallel second-stage Ho:YAG amplifiers. Additionally, a ZnGeP2 MOPA system was demonstrated using the Ho:YAG MOPA as the pump source, achieving high power output with good beam quality.