BETA-BAB2O4 PHASE-MATCHING-DIRECTION GROWTH BY THE CZOCHRALSKI METHOD

beta-BaB2O4 (BBO) phase-matching-direction growth was carried out by t he Czochralski (CZ) method. Cylindrical BBO seed crystals, 4 mm in dia meter and 25 mm in length, were used along the Nd:YAG laser-SHG, THG, and FHG phase-matching directions (theta = 22.8, 31.1, 47.6 degrees). The tips of the seeds were tapered to 2.5 mm and etched with phosphori c acid at 100 degrees C for 2 min. BBO crystals were pulled from a sto ichiometric BaB2O4 melt. The melt temperature was decreased at a fixed rate to avoid large temperature fluctuations at the growth interface. High-quality BBO crystals (15 mm in diameter and 70 mm in length) wer e grown along each of the phase-matching directions. This growth techn ique will contribute to the high-production yield of BBO crystals for nonlinear optical devices.