Controlled Habit and Growth, and Electrooptic Evaluation of Organic Nonlinear Optical 4-Dimethylamino-N-Methyl-4-Stilbazolium Tosylate (DAST) Crystals

The habit of organic 4-dimethylamino-N-methyl-4-stilbazolium tosylate (DAST) crystals was successfully controlled by modifying their growth conditions. DAST solutions of different concentrations exhibited different aspect ratios (length/thickness). In addition, we measured the electrooptic (EO) sensitivity of DAST crystals using external EO probing to evaluate their crystallinity. The EO signal power obtained from the DAST crystals was proportional to crystal thickness. This result showed that the crystallinity of DAST crystals was maintained irrespective of their thicknesses. We also observed that the EO signal from DAST was about 30-fold larger than that of KTiOPO4 (KTP) with the same thickness.