An analysis of guided modes and effective refractive indexes in c-cut Ti-diffused LiNbO3 strip waveguides has been performed at the wavelength 1.53 \mu m by the variational method. Dependences of mode size and effective refractive index on initial Ti-strip width W, diffusion temperature T and initial Ti-strip thickness H have been calculated for several lower order modes. As compared the plots of the mode size with the previous published experimental results, an agreement in general behavior has been obtained. The single-mode and cutoff conditions were discussed numerically, which are very useful in optimizing and designing the Er:Ti:LiNbO3 waveguide devices. In addition, several advantages of 1.48 \mum pumping were summarized.
Delong Zhang, Guilan Ding, and Caihe Chen, "Theoretical Analysis of Guided Mode and Effective Refractive Index at 1.53\;\mum in Ti:LiNbO3 Strip Waveguides," J. Lightwave Technol. 16, 459- (1998)