Electrooptic characterization of PLT28 thin films by a guided-wave optical technique

Transparent La-modified PbTiO₃ (PLT₂₈) thin films were deposited on sapphire substrates by rf magnetron sputtering for optical purpose. The influence of postdeposition annealing conditions on the optical properties of the films was investigated in this study. Guided optical wave techniques based on prism-coupling and optical transmission method were carried out to determine the dispersion of refractive indices. Furthermore, electrooptic (EO) effects of PLT₂₈ thin films prepared with optimum annealing conditions were determined by a technique measuring the change of the resonant coupling angle in the experiment. The results have shown that the optical properties were strongly affected by the annealing process. The linear EO coefficient r₁₃ obtained is about 55pm/V which is much larger than those of the well-known LiNbO₃ material