Growth and properties of large aperture YCOB crystal for NLO application

Abstract Yttrium calcium oxyborate (YCOB) is one of commonly used nonlinear optical (NLO) crystals with good thermal and NLO properties. In this work, large YCOB crystals without cleavage were grown by the Bridgman (Br) method, and crystal element with the size of 102 mm×100 mm×18 mm was harvested for the first time, which is the largest aperture up to now to the best of our knowledge. The optical absorption, homogeneity and bulk laser induced damage threshold (LIDT) were analyzed detailedly. The type-I phase-matched nanosecond (ns) second-harmonic generation (SHG) and picosecond (ps) SHG in YCOB XZ plane (29.1°, 180°) were also demonstrated. The highest SHG conversion efficiency of 73% were achieved from a fundamental source with 2 Hz repetition rate and 50 ps pulse duration at 1053 nm in the 10 mm long YCOB Crystal. It is believed that based on this work, YCOB crystal elements with high quality and large aperture will be used in high power laser system in the near future.