Electro-optic characterization of (Pb, La)TiO3 thin films using prism-coupling technique

Transparent ferroelectric (Pb, La)TiO3 thin films were grown by rf magnetron sputtering on (0001) Al2O3 substrates. The prism coupling technique was used to determine the refractive indices of the obtained planar waveguides (n(0) = 2.3745 and n(e) = 2.2705 at 633 nm). Measurements by such a guided-waves technique have also been of considerable interest for studying the anisotropic nature of films. Furthermore, electro-optic effects were investigated in this study using the change of the resonant coupling angle. The latter is induced by the refractive index variation caused by the electro-optic effect when an electric field is applied to the film. The linear electro-optic coefficient r(13), thus obtained, is about 55 pm/V. This high value illustrates the suitability of this material for optical applications such as optical switches and electro-optic modulations. (C) 1999 American Institute of Physics. [S0021-8979(99)05703-5].