  High-refractive-index semiconductor optical waveguides form the basis for
modern photonic integrated circuits (PICs) , but the conventional methods of
achieving optical confinement require a thick lower-refractive-index support
layer that impedes large-scale co-integration with electronics. To address this
challenge, we present a general architecture for single-mode waveguides that
confine light in a high-refractive-index material on a native substrate. Our
waveguide consists of a high-aspect-ratio fin of the guiding material
surrounded by lower-refractive-index dielectrics and is compatible with
standard top-down fabrication techniques. The proposed waveguide geometry
removes the need for a buried-oxide-layer in silicon photonics, as well as the
InGaAsP layer in InP-based PICs and will allow for photonic integration on
emerging material platforms such as diamond and SiC.
