Alignment control of a liquid crystal on a photosensitive polyvinylalcohol film

The photoinduced optical anisotropy of an azo dye-doped polyvinylalcohol film has been utilized for controlling the azimuthal alignment of a liquid crystal. The dynamic behaviors of the optical transmission of the film and of a liquid crystal layer aligned on the film are studied using linearly polarized pumping (Ar + laser) and probing (He-Ne laser) beams. The results show that the azo dye-doped polyvinylalcohol film memorizes the information on the polarization direction of the exciting laser beam and the resulting anisotropy induced in the film causes adjacent liquid crystal molecules on the film to rotate azimuthally.