MW-Peak-Power Nanosecond Mid-Infrared Optical Parametric Amplifier Based on BaGa₄Se₇ Crystal

A BaGa<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub>Se<sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</sub> (BGSe) crystal based optical parametric oscillator and amplifier system with 1064 nm laser pumping is demonstrated in this letter. A double-pass pumped optical parametric oscillator was employed to generate the tunable mid-infrared seed. Direct amplification of mid-infrared seed by BGSe crystal was first demonstrated in this work. A maximum output energy of 13.34 mJ was obtained at 3.88 μm with pulse width of 8.1 ns, corresponding to peak power of 1.65 MW. The overall conversion efficiency from 1064 nm to 3.88 μm laser was 12.0%. The optical parametric source shows wideband idler tunability in the range of 3.34-4.54 μm. The present results confirm the great potential of BGSe crystal in mJ-energy, MW-peak-power, tunable mid-infrared pulse generating from a commercially 1 μm laser pumped system.