161 W middle infrared ZnGeP<sub>2</sub> MOPA system pumped by 300 W-class Ho:YAG MOPA system
Gaoyou Liu, Shuyi Mi, Ke Yang, Disheng Wei, Junhui Li, Baoquan Yao, Chao Yang, Tongyu Dai, Xiaoming Duan, Lixin Tian, Youlun Ju
Abstract
We demonstrated a high-power <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mi>Q</mml:mi> </mml:math> -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 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msub> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:mi mathvariant="normal">Z</mml:mi> <mml:mi mathvariant="normal">n</mml:mi> <mml:mi mathvariant="normal">G</mml:mi> <mml:mi mathvariant="normal">e</mml:mi> <mml:mi mathvariant="normal">P</mml:mi> </mml:mrow> <mml:mn>2</mml:mn> </mml:msub> </mml:mrow> </mml:math> MOPA system was demonstrated using the Ho:YAG MOPA as the pump source. A maximum average output power of 161 W at 3–5 µm was obtained with 290 W incident Ho pump power, corresponding to beam quality factors <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"> <mml:mrow class="MJX-TeXAtom-ORD"> <mml:msup> <mml:mi>M</mml:mi> <mml:mn>2</mml:mn> </mml:msup> </mml:mrow> </mml:math> of 3.42 and 3.83 for horizontal and vertical directions, respectively.