PREDICTION OF SPACE-CHARGE DENSITY AND SPACE-CHARGE FIELD IN THERMALLY ION-EXCHANGED PLANAR SURFACE WAVE-GUIDES

Using an accurate analytical expression for describing the numerical s olution of the diffusion equation in planar ion-exchanged waveguides, we present normalized depth profiles for space-charge field and densit y as a function of the mismatch in the self diffusion coefficients of the two cations. Our results are presented in terms of analytical expr essions as well as universal curves, useful for any cation pair, subst rate glass, or salt. It is also shown that most of the analytical expr essions for the refractive index profile used in the literature yield unphysical results.