Influence of transition layers on the dispersion characteristics of film optical waveguides prepared by the method of reactive cathodic sputtering

A transition layer was found between a film and its substrate in planar optical waveguides prepared by the method of reactive cathodic sputtering. The depth and profile of this layer were determined. A spectrum of the effective refractive indices found experimentally did not agree with a spectrum predicted by the theory of thin-film waveguides. Dispersion equations were derived to allow for the presence of a transition layer and they predicted a spectrum of the effective refractive indices which agreed with the experimental results.