Abstract

One of the most difficult problems to treat theoretically in integrated optics is that of radiation loss through scattering from random imperfections of the waveguide walls. Previous approaches to this problem have been based on coupled-mode analysis,¹ with the radiation loss described by coupling between guided and radiation modes of the optical waveguide. Unfortunately this approach suffers from a number of drawbacks. Among these is the complexity of the final result for the power loss coefficient and from which it is extremely difficult to discern the important parameters in controlling waveguide loss. Furthermore, the coupled-mode approach is difficult to apply to rib and rectangular guides, for which there is no exact expression for the radiation modes. With these difficulties in mind, we have developed a new and much simpler approach to the problem of radiation loss based on treating the waveguide imperfections as a set of randomly distributed antennas, or sources.

© 1990 Optical Society of America