Light Scattering with Heterogeneous Core – Cladding Boundary in Dielectric Waveguide

Light scattering in dielectric waveguide is caused, inter alia by random heterogeneity of boundary separating core and cladding layers. Rigorous mathematical approach to the problem consists in solving Maxwell equations with stochastic boundary conditions, what seems to be inconvenient in practice. The reasonable alternative is to treat the heterogeneous boundary as perturbation of the refractive index in the thin boundary layer. In this case the vector wave equation reduces to the equations for random amplitudes of coupled modes, where the coupling depends on spatial correlations of the refractive index. In this paper we establish the analytic connection between the models of the heterogeneous boundary surface and the perturbed refractive index. We express the refractive index correlations in terms of the surface correlations. We investigate the coupling of orthogonally polarized modes and estimate scattering in planar optical waveguide