Third-order optical nonlinearities in new octupolar molecules and their dipolar subunits

The third nonlinear optical susceptibility (chi ((3))) of a new family of o ctupolar molecules with one, two, and three double bonds has been measured at 532 in tetrahydrofuran solutions by the degenerate four-wave mixing (DFW M) method. For comparison, we also measured the analogous dipolar subunits of the molecules. The second hyperpolarizability (gamma) for these molecule s was deduced. We found that octupolar molecules exhibit large second-order hyperpolarizability (gamma) values. The gamma values obtained for octupola r compounds are approximately 10 times larger than those of their correspon ding dipolar subunits and 10(4) times larger than those of CS2, which is a reference material for DFWM. (C) 2001 Optical Society of America.