Integrated optical waveguides in LiNbO3:: Modelling and experimental analysis

Graded-index optical channel waveguides are fabricated by diffusion of Ti in LiNbO3. A model has been developed for calculating the mode profiles of the same, by first finding the effective refractive index profile along the lateral direction, and then discretising the profile and applying the matrix method This effective-index-based matrix method (EIMM) has been presented in this paper and established as a computationally fast, analytical method to compute modal electric field and intensity profiles in single and coupled graded-index channel waveguides. The method can be used in coupled systems consisting of three or more waveguides where the input power may be launched to any of the waveguides. Some of the computed intensity profiles have been compared with experimental data. Although computation and measurements have been performed only for TE and TM polarisations, the method has the inherent capability of handling arbitrary polarisation.