Spectral characteristics of second-order optical nonlinearities in poled polymer films containing charged chromophore aggregates

We report measurements of the frequency dependence of anomalous second-order electric susceptibilities of polymer films containing hyperpolarizable chromophore guest molecules and poled using coplanar electrodes. The frequency dependence, polarization dependence, and magnitude of the observed second-order susceptibilities are radically different from those of conventional corona-field poling experiments and cannot be explained by isolated chromophore models. These observations and the results of sum-over-states perturbative electronic structure calculations argue for the importance of positively charged chromophore aggregates.