We show that by placing a slab of semiconductor material between two photonic bandgap (PBG) mirrors, waveguide modes at frequencies out of the PBG can be obtained. These modes are similar to the modes of a conventional dielectric slab waveguide. Using these modes, we can obtain very good coupling between a PBG waveguide and a dielectric slab waveguide with similar slab properties. We discuss the properties of these slab modes and outline the guideline for the optimization of the PBG waveguides based on these properties.
Ali Adibi, Yong Xu, Reginald K. Lee, Amnon Yariv, and Axel Scherer, "Properties of the Slab Modes in Photonic Crystal Optical Waveguides," J. Lightwave Technol. 18, 1554- (2000)