Embodiments of the invention describe heterogeneous photonic integrated circuits (PIC) wherein a first silicon region is separated from the heterogeneous semiconductor material by a first distance, and a second silicon region is separated from the heterogeneous semiconductor material by a second distance greater than the first distance. Thus embodiments of the invention may be described as, in heterogeneous regions of a heterogeneous PIC, silicon waveguides using multiple heights of the silicon waveguide, or other structures with multiple offset heights between silicon and heterogeneous materials (as described herein).