## Abstract

We report on the linear and nonlinear optical properties of the novel organic crystal $4\text{-}N$, *N*-dimethylamino-${4}^{\prime}\text{-}{N}^{\prime}$-methyl-stilbazolium 2,4,6-trimethylbenzenesulfonate (DSTMS). The principal refractive indices ${n}_{1}$, ${n}_{2}$, and ${n}_{3}$ have been determined by a direct measurement of the group index dispersion over a broad wavelength range from $0.6\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}1.6\text{\hspace{0.17em}}\mu \mathrm{m}$. The linear absorption coefficients for light polarized along the dielectric axes have been measured in the transparency range from $600\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}2000\text{\hspace{0.17em}}\mathrm{nm}$. DSTMS crystals show a large birefringence of $\Delta n=0.5$ and low absorption $\alpha <0.7\text{\hspace{0.17em}}{\mathrm{cm}}^{-1}$ in the telecommunication wavelength range at $1.55\text{\hspace{0.17em}}\mu \mathrm{m}$. Furthermore, the nonlinear optical tensor elements ${d}_{111}$, ${d}_{122}$, and ${d}_{212}$ have been determined by the Maker-fringe technique at the fundamental wavelength of $1.9\text{\hspace{0.17em}}\mu \mathrm{m}$. DSTMS crystals exhibit a very large nonlinear activity with a nonlinear optical coefficient ${d}_{111}=214\pm 20\text{\hspace{0.17em}}\mathrm{pm}\u2215\mathrm{V}$. Phase-matching curves determined from our optical data showed that parametric oscillation can be achieved in the wavelength range from $1\phantom{\rule{0.3em}{0ex}}\text{to}\phantom{\rule{0.3em}{0ex}}2.2\text{\hspace{0.17em}}\mu \mathrm{m}$ with effective nonlinear optical coefficients larger than $25\text{\hspace{0.17em}}\mathrm{pm}\u2215\mathrm{V}$.

© 2007 Optical Society of America

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