High Energy Picosecond Mid-Infrared Optical Parametric Amplifier Based on KTiOAsO4 Crystal

A mJ-level picosecond mid-infrared (MIR) optical parametric amplifier (OPA) with a KTiOAsO4 (KTA) crystal was demonstrated for the first time. This MIR OPA was pumped by a 10 Hz, 30 ps, 1.06 mu m Nd:YAG laser. The injection seed of MIR OPA was provided by a tunable near-infrared (NIR) OPG/OPA output with a beta-BaB2O4 (BBO) crystal. The maximum idler energy of 1.85 mJ at 3.5 mu m was obtained under a 20 mJ pumping energy at 1.06 mu m. The pump to idler efficiency was 9.25%. The photon conversion efficiency was 30.4%. The 2.9-3.6 mu m tuning performance of idler light in KTA-OPA was also investigated. The idler energies were 0.6 mJ at 2.9 mu m and up to 1.4 mJ at 3.6 mu m under a 14 mJ pumping energy at 1.06 mu m. Moreover, the pulse temporal shape evolutions of the parametric lights in KTA-OPA process were simulated. The pulsewidth of the generated idler light was given.