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 of such relations are presented in 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.
Angelo Passaro, Marcos Antonio Ruggieri Franco, Nancy Mieko Abe, and Francisco Sircilli, "The Effect of the Proton-Concentration-to-Refractive-Index Models on the Propagation Properties of APE Waveguides," J. Lightwave Technol. 20, 1573- (2002)