Visible and UV effective non-linear optical coefficients of β-BaB2O4 as function of the growth technique

Abstract We report second and fourth harmonic generation measurements in β-BaB2O4 single crystals (β-BBO) cut in the type I phase matching direction for the conversions from 1064 to 532 nm and from 532 to 266 nm. The absolute values of the effective non-linear optical coefficients deff are determined by measuring the conversion efficiency towards the visible and the UV. Crystals grown by the Czochralski method (directly pulled from a supercooled pure melt) are compared with crystals produced by the usual high temperature top seeded solution growth method. No difference in the effective non-linear optical coefficients was observed for the conversion from 1064 to 532 nm. In contrast, a systematically slightly higher deff value of crystal grown by the Czochralski method is obtained for the conversion from 532 to 266 nm.