Incongruent Melting Laxyysc4-X-Y(Bo3)(4): Lysb Nonlinear Optical Crystal Grown By The Czochralski Method

Nonlinear optical (NLO) crystals with incongruent melting of LaxYyScz(BO3)(4) (x + y + z = 4) (LYSB)-type were grown for the first time, to the best of our knowledge, by the Czochralski method. A special thermal assembly was used and the melt composition, growth direction, and the pulling and rotation rates have been optimized. Good optical quality LYSB crystal with a diameter of about 13 mm and a length of 25 mm has been grown from the La0.765Y0.485Sc2.75(BO3)(4) starting melt composition, along the c-axis direction, using a slow rotation rate of 8-10 rpm and a high pulling rate of 2 mm/h. The grown crystal has an acentric huntite-type structure (space group R32, Z = 3) with cell dimensions a = 9.8098(4) angstrom and c = 7.9802(3) angstrom, and its chemical composition was determined to be La0.78Y0.32Sc2.90(BO3)(4). The optical transmission and the refractive indices were determined, and the second harmonic generation (SHG) and sum frequency generation (SFG, omega + 2 omega) properties were reported. The laser damage threshold was also determined to be similar to 2.0 GW/cm(2) at 1064 nm (6 ns pulses). The main nonlinear properties of Czochralski-grown LYSB crystal were found to be similar to those of flux-grown LYSB, and comparable to YAl3(BO3)(4) (YAB) nonlinear properties. The big advantage of Czochralski-grown LYSB crystals is that they can be grown with large size and high quality, making them promising candidates for various NLO applications, including frequency conversion of high-average power radiation sources.