The effect of the proton-concentration-to-refractive-index models on the propagation properties of APE waveguides

This work analyzes the effect of the proton-concentration-to-refractive-index relation on the computation of waveguiding properties of well-annealed proton-exchanged channel waveguides fabricated in a LiNbO₃ substrate. Several such relations are presented in the literature. The application of these different relations in the numerical analysis results in a very different propagation behavior for the waveguide. For comparison purposes, an empirical relation that fits the published refractive-index-versus-proton-concentration experimental data for the α crystalline phase is also used.