Comparison of losses in imperfect surface-diffused and buried optical waveguides

Abstract
Theoretical expressions for the scattering losses caused by surface imperfections in both buried guiding layers with a cosh−2 (x/d) index distribution and surface-diffused waveguides with an exponential profile are presented. Theoretical comparison of radiation losses in buried, surface-diffused, and uniform abrupt guides indicates that, in general, buried layers have lower losses, in agreement with experimental evidence.