Growth And Properties Testing Of The New Ultraviolet Nonlinear Optical K₂Al₂B₂O₇

In the first part of this thesis, a comprehensive review has been given on the recent development of the nonlinear optical material, especially the borate series. On the basis of the improvement on the crystal growth furnace, the new NLO crystal K2Al2B2O7(KABO) has been grown by the top-seeding flux method. Several flux systems have been studied, especially about the mixed flux system. We found that the use of mixed systems such as K2CO3-B2O3-NaF had greatly decreased the viscosity of the melt, decreased the saturation point and improved the growth quality of the crystal. The flux system NaF-B2O3 is favour of decreasing the volatilization and the saturation point of the melt.Several linear and nonlinear optical properties of KABO crystal have been tested. Its transparence range covers 180nm to 3600nm . The refractive indices at 12 wave lengths in the visible region were measured with the minimum deviation method, showing that KABO is a negative uniaxial optical crystal with moderate birefringence .The measurement of nonlinear optical coefficient dn=0.45pm/v. The conversion efficiency of fourth-harmonic generation (FOHG) is 14.7%.