Resonant third-order nonlinear optical response of molecular and crystalline cyanine dyes

Resonant nonlinear optical processes in highly concentrated molecular systems are interesting subjects from the following points of view. One is that in these systems the enhancements of optical nonlinearities are expected by the delocalization of excitations due to molecular aggregation. The other is that the conventional perturbative description of optical nonlinearities may not be available because of the strong coupling between light and matter. In this paper, we reported the resonant third-order nonlinear optical properties of cyanine dyes in two kinds of molecular system.