Effect of roughness and inhomogeneity on evanescent single-mode optical couplers

The authors investigate the effect of surface roughness and material inhomogeneity on optical coupling in buried-channel, single-mode, evanescent couplers using a stochastic analysis. The results predict that there is no reduction in total power coupling between the cores, but there is a slight modulation of the coupling length and a loss of power from the coupler through scattering.