A novel photodynamic azo polyelectrolyte was synthesized by incorporating azobenzene units into poly(acrylic acid) backbone and used as a polyanion. This polyelectrolyte was assembled into multilayer thin films by an electrostatic layer-by-layer deposition technique in conjunction with a polycation. Studies on the optical properties such as photoinduced surface relief gratings and dichroism of the multilayer films and spin-coated films were carried out. Good quality surface relief structures on the spin-coated film were clearly generated when exposed upon the polarized interferencing Ar+ laser beams, yet no surface relief structures occurred on the multilayer films of the synthesized azo polyelectrolyte investigated by atomic force microscopy. The extent of photoinduced dichroism of the films was evaluated by dichroic ratio and orientational order parameter from their polarized absorption spectra. (C) 2003 Elsevier B.V. All rights reserved.