The opportunity of using ferroelectric (Pb, La), (Zr, Ti)O3thin films has been extensively studied for making integrated optic devices since they are expected to have potential optical properties. The configurations of the optical waveguide and the metallic electrodes are considered as the basic elements in fabrication schemes. Design rules are given in this study for the analysis of three-dimensional structures using theoretical tools, i.e., the Effective Index Method and Beam Propagation Method. Definition of the optogeometrical parameters, i.e., film thickness, rib width and height, coupling length, is essential for enhancing waveguiding performances. The optimization has been proposed taking into account the actual advance of the etching technology. Results are reported for planar optical waveguides.