Midinfrared Optical Parametric Amplifier With 6.4–11 $\mu \text{m}$ Range Based on BaGa₄Se₇

Abstract

A widely tunable picosecond midinfrared (MIR) optical parametric amplifier (OPA) with wavelength ranging from 6.4 to 11 μm based on the 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> crystal was demonstrated. The MIR OPA was pumped by a 30 ps 1064-nm Nd:YAG laser and injected by a KTiOPO <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">4</sub> (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 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> was investigated. The output energies were measured to be ~38 μJ at 11 μm and up to ~100 μJ at 6.4 μm under pumping energy of ~4.1 mJ. Further, the type-I phase-matching angles of 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> crystal for idler light generation in the range of 6.4-11 μm were experimentally measured and the discrepancy between the experiment and theoretical calculation was discussed.