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

Transparent ferroelectric (Pb, La)TiO3 thin films were grown by rf magnetro n sputtering on (0001) Al2O3 substrates. The prism coupling technique was u sed 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-w aves technique have also been of considerable interest for studying the ani sotropic nature of films. Furthermore, electro-optic effects were investiga ted in this study using the change of the resonant coupling angle. The latt er 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-o ptic coefficient r(13), thus obtained, is about 55 pm/V. This high value il lustrates the suitability of this material for optical applications such as optical switches and electro-optic modulations. (C) 1999 American Institut e of Physics. [S0021-8979(99)05703-5].