Improved Growth Techniques for Nonlinear Optical Crystal CsB3O5 Based on the Investigation of Defects

Abstract

Growth defects in CsB3O5 (CBO) crystals grown using the seed-submerged growth technique (SSGT), which includes parallel grouping, growth step, and inclusion, were observed and analyzed. Dislocation was investigated using the chemical etching method for the first time. Relationships between defects and growth conditions are discussed, and ways to overcome growth defects are suggested. Using the cool-end compensation of thermocouples, a CBO crystal measuring 63 × 40 × 30 mm3 (weighing 190 g) was successfully grown using the SSGT. Adopting the top seeded solution growth (TSSG) method, a scattering centers-free CBO crystal measuring 75 × 52 × 46 mm3 (weighing 480 g) was obtained from the improved Cs2O–B2O3–MoO3 system with a molar ratio of (1–3):(1.5–3.5):(1–4), which is the largest CBO single crystal to date.