This Letter introduces a Semiconductor-Under-Insulator (SUI) technology in InP for designing strip waveguides that interface InP photonic crystal membrane structures. Strip waveguides in InP-SUI are supported under an atomic layer deposited insulator
layer in contrast to strip waveguides in silicon supported on insulator. We show a substantial improvement in optical transmission when using InP-SUI strip waveguides interfaced with localized photonic crystal membrane structures when compared with extended photonic crystal waveguide membranes. Furthermore, SUI makes available various fiber-coupling techniques used in SOI, such as sub-micron coupling, for planar membrane III-V systems.
