Single-Mode Optical Waveguides on Native High-Refractive-Index Substrates

Abstract: 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.