Analysis of a multilayer coated optical planar waveguide termination

The coupling efficiency of a multilayer coating in front of an abruptly terminated symmetric dielectric planar waveguide is investigated analytically, by means of an integral equation, appropriate for the boundary value problem of TE modes. This integral equation is solved approximately by a Neumann series procedure giving highly accurate results when the difference of the refractive indices between the core (n2 and cladding (n1 regions is small. The reflection coefficient of the guided waves is computed inside the optical waveguide. The radiation pattern at the far field region is also computed. Numerical results are presented for GaAlAs and InGaAsP laser diodes. Comparison with previously published results for a single layer coated optical waveguide is also given.