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

A BaGa4Se7 (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~\mu $ m 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~\mu $ m laser was 12.0%. The optical parametric source shows wideband idler tunability in the range of 3.34- $4.54~\mu $ m. 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~\mu $ m laser pumped system.