Midinfrared Optical Parametric Amplifier With 6.4-11 μm Range Based on BaGa4Se7

A widely tunable picosecond midinfrared (MIR) optical parametric amplifier (OPA) with wavelength ranging from 6.4 to 11 mu m based on the BaGa4Se7 crystal was demonstrated. The MIR OPA was pumped by a 30 ps 1064-nm Nd:YAG laser and injected by a KTiOPO4 (KTP)-based narrow-bandwidth widely tunable near-infrared seed. The wide spectral generation using type-I (o -> e + e) critically phase-matched parametric amplification in BaGa4 Se-7 was investigated. The output energies were measured to be similar to 38 mu J at 11 mu m and up to similar to 100 mu J at 6.4 mu m under pumping energy of similar to 4.1 mJ. Further, the type-I phase-matching angles of BaGa4Se7 crystal for idler light generation in the range of 6.4-11 mu m were experimentally measured and the discrepancy between the experiment and theoretical calculation was discussed.