Transparent lanthanum-modified lead zirconate titanate (PLZT) thin films with electro-optic properties were deposited on indium-doped tin oxide (ITO) coated glass by pulsed laser deposition (PLD). Stoichiometric films with the crystallographic perovskite structure required for electro-optical behaviour, and a composition ratio close to 9/65/35 were obtained. The microstructural, optical and electro-optic properties of these films were studied for different substrate temperatures, T-s, and reactor oxygen pressure, P-O2 The films annealed at 700 degreesC in oxygen at atmospheric pressure are highly (I 10) perovskite orientated and free of the undesired pyrochlore phase. The optical constants (n and k as a function of wavelength) of the films were obtained using variable angle spectroscopic ellipsometry (VASE) and spectrophotometry in the UV-Vis-NIR regions. They appear to be strongly depending on the deposition conditions. A high quadratic electro-optic coefficient, close to that of the bulk value, was obtained at 632.8 nm by single-beam (ellipsometric) configuration. (C) 2003 Elsevier B.V. All rights reserved.