Recent progress on acentric La₃Nb₀.₅Ga₅.₅O₁₄ crystals: large-size growth and application to ultrafast mid-infrared laser systems

Optical parametric chirped-pulse amplification (OPCPA) can be used to generate ultrafast intense mid-IR lasers, however, the lack of suitable nonlinear optical crystals simultaneously having a wide transmission range, high laser damage threshold, and excellent phase-matching property hinders the development of mid-IR OPCPA. Here, we focus on the La3Nb0.5Ga5.5O14 (LGN) crystal and describe its growth, characterization, and application in mid-IR nonlinear frequency converters. We discuss the optimization of the starting polycrystalline component and temperature field aimed for the growth of large-size LGN crystals with a 60 mm diameter. We then present a detailed characterization of their optical properties, including transmission spectrum, refractive indices, and nonlinear coefficient. Our findings suggest the promising potential of LGN in generating both few-cycle pulses across 3 to 6 µm and terawatt-class OPCPA systems around 5 µm.