SELECTIVE EPITAXIAL GROWTH TECHNIQUE FOR FABRICATING WAVEGUIDES FOR INTEGRATED OPTICS

This disclosure concerns optical waveguides of semiconductor material through which light is adapted to be propagated. The optical waveguides comprise respective first and second layers of semiconductor material of the same conductivity type, wherein one of the semiconductor layers has a relatively low refractive index, while the other semiconductor layer has a relatively high refractive index, with the light being adapted to be propagated through the semiconductor layer having the relatively high refractive index. The optical waveguide structures are characterized by having the semiconductor layer through which the light is to be propagated so formed as to include each of its two side surfaces and top surface as being planar faceted growth surfaces of extreme smoothness to avoid scattering light as it is being propagated therethrough, thereby minimizing losses. In a particular aspect, an optical waveguide is provided in which each of its four planar surfaces including top, bottom, and side surfaces is formed as a smooth planar faceted growth surface, the optical waveguide comprising a second epitaxial deposit having a relatively high refractive index disposed atop a first epitaxial deposit in co-extensive relationship therewith, wherein the first epitaxial deposit is of the same conductivity type having a lower refractive index and being so formed on a substrate as to include its side surfaces and top surface as smooth planar faceted growth surfaces.