Cascaded contributions to degenerate four-wave mixing in an acentric organic crystal

We show both theoretically and experimentally by degenerate four-wave mixing that the combined processes of optical rectification and the linear electro-optic effect contribute to the large effective third-order susceptibilities $\left[14{\chi }^{\left(3\right)}\left({\mathrm{CS}}_2\right)\right]$ of the organic salt $4‐N,\widehat{N}‐\mathrm{dimethylamino}‐4^{\prime }‐N^{\prime }$-methylstilbazolium $\mathrm{toluene}‐p‐\mathrm{sulfonate}$ (DAST). Furthermore, the knowledge of the cascaded contributions was used to determine absolute values of the third-order susceptibilities as well as their sign.