Growth of Ultrathin and Highly Efficient Organic Nonlinear Optical Crystal 4′-Dimethylamino-<i>N</i>-methyl-4-Stilbazolium <i>p</i>-Chlorobenzenesulfonate for Enhanced Terahertz Efficiency at Higher Frequencies

Abstract

Growth of an ultrathin (thickness as low as 23 μm) organic nonlinear optical crystal of 4′-dimethylamino-n-methyl-4-stilbazolium p-chlorobenzenesulfonate (DASC) has been achieved by the slope nucleation method for generating THz waves with relatively higher efficiencies especially at higher frequencies. The propensity of lower solubility of this material in methanol solvent as compared to 4′-dimethylamino-n-methyl-4-stilbazolium tosylate (DAST) was favorably exploited to obtain these thin crystals. The DASC crystals thus obtained were studied for the generation of THz waves, and their efficiency was compared with DAST and zinc telluride (ZnTe) single crystals. The enhancement THz efficiency observed in thinner DASC could be attributed to better velocity matching and weaker absorption as compared to thicker crystals of the same material.