Formation and properties of proton-exchanged Z-cut MgO: LiNbO₃ crystal waveguides

Proton-exchanged waveguides of Z-cut LiNbO₃ (LN) doped with different contents of MgO are fabricated in benzoic acid. The effective refractive indexes of the guided modes are measured by prism-coupling method at different wavelengths of 480 nm, 514.5 nm, 532 nm, 632.8 nm and 1064 nm respectively, and the dispersion of the refractive index increments of the waveguides is given. The refractive index profiles are obtained by IWKB method and the diffusion coefficients are calculated. The results show that the waveguides have the step-like profiles and the diffusion characteristics are influenced by the doping MgO contents in the LiNbO₃ crystal. The diffusion mechanisms are discussed finally.