Photoassisted poling, at room temperature, of dye molecules in amorphous films

The photoisomerization of some anisotropic molecules modifies their orientational order and induces a macroscopic anisotropy which produces a dichroism and a birefringence. Starting from this well known property, we have demonstrated that the photoisomerization of some polar molecules, in the presence of a DC electric field, can induce the orientation of molecular dipoles, at room temperature, in materials for which this poling is possible only at high temperature (above T_g ), in the absence of optical pumping. This technique is promising for producing non centrosymmetric polymer (or sol-gel) films with second order optical nonlinearities patterned by photolithographic methods (for integrated optics: modulators, harmonic generation)