Abstract

Efforts are being made to grow large crystals of organics by different methods, in order to investigate the nonlinear optical (NLO) properties and applications. Among them the following techniques are commonly used: low temperature solution growth using temperature lowering and temperature difference methods; from melt by Czochralski and Bridgman - Stockbarger methods; and from physical vapor transport method. In the present paper, we report the growth of a new NLO crystal 3-methoxy-4-hydroxy-bezaldehyde (MHBA) by modified solution and Czochralski methods for the first time. The growth behavior of MHBA crystals grown in different solvents and the effect of solvents on the crystal habit have been studied. The crystal show different morphological characteristics and growth rates in different solvents with different crystallographic orientations. A new solution crystal growth technique developed in this laboratory was used in growing solution growth crystals. In this technique the solution temperature is lowered at a programmed rate to create supersaturation along with6 pulling the seed from the growth solution at a slow rate. In this way the general problem of needle shape growth in organic materials was eliminated. A modified Czochralski crystal growth system designed and fabricated earlier for the production of organic NLO crystals is used for this study. One of the most important features of this system is that the entire growth process including the solid-liquid interface can be viewed from any direction.

© 1994 Optical Society of America