Dependence of Second-Harmonic-Generation Coefficients of LiNbO3 on Melt Composition

Abstract

The three nonlinear coefficients d31, d22, and d33 that describe optical second-harmonic generation with LiNbO3 have been determined for crystals pulled from melts with Li/Nb atom ratios, (Li/Nb)m, of 0. 852, 0. 946, and 1. 083. The coefficients d22 and d33 were found to be insensitive to the melt composition whereas d31 increased by about 50% as (Li/Nb)m was increased from 0. 852 to 1. 083. These results suggest a marked Curie temperature dependence of the difference between the two Nb–O bond nonlinearities that give rise to the d's for LiNbO3.