Ion exchange model for /spl alpha/ phase proton exchange waveguides in LiNbO/sub 3/

An H/sup +//Li/sup +/ exchange model is found to be applicable to describe the diffusion of protons when optical waveguides are formed in LiNbO/sub 3/ by proton exchange methods where the proton doped crystal structure stays in the pure /spl alpha/ phase. The H/sup +/ and Li/sup +/ self-diffusion coefficients in the ion exchange model are determined as a function of the proton exchange temperature both for x-cut and z-cut LiNbO/sub 3/. In this way a very useful tool for predicting the proton concentration profiles and hence the refractive index profiles of /spl alpha/ phase proton exchange LiNbO/sub 3/ waveguides is achieved.