Guiding mechanisms in dielectric-core photonic-crystal optical waveguides

We show that the main guiding mechanisms in dielectric-core photonic crystal optical waveguides are total internal reflection and distributed Bragg reflection. We also show that by placing a slab of semiconductor material between two photonic band gap (PBG) mirrors, we can obtain waveguide modes at frequencies out of the photonic bandgap. 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.