A dual molecular and photonic engineering perspective in molecular nonlinear optics: ellipsometric control of optical poling

We demonstrate the possibility of controlling the symmetry of the susceptibility tensor of polymer films prepared by a photoinduced all-optical poling process. A rotationally invariant model is developed so as to analyse the underlying tensorial molecule-field coupling. The multipolar character of the `write' poling field is shown and implemented by way of ellipsometric polarization features, while selection rules connecting the rotational spectrum of the molecular hyperpolarizability to that of the write field tensor E are expressed in terms of molecular symmetry and spectroscopic properties, on the one hand, and electromagnetic polarization states, on the other hand. By means of adequate ellipsometric adjustment of the write field tensor symmetry, the possibility to monitor the multipolar anisotropy of the macroscopic susceptibility tensor is demonstrated on a grafted dispersed red 1 methylmetacrylate polymer thin film.