Slab modes in photonic crystal optical waveguides

Abstract

Photonic crystals with line defects can be used for guiding light. In all the proposals and demonstrations of photonic bandgap (PBG) waveguides, the guiding modes were restricted to the photonic bandgap. We show that there exist some guiding modes outside the photonic bandgap. We also show that by using these modes, which we refer to as the slab modes, efficient power transfer from a dielectric slab waveguide to a PBG waveguide over a range of frequency wider than the photonic bandgap (PBG) can be obtained. Different properties of the slab modes of a PBG waveguide is also discussed.