Coupling of light in graded effective index photonic crystal waveguides

Summary form only given. The optical impedance mismatch experienced by light propagating across high-low index waveguide-photonic crystal (PC) interface is one of the main issues regarding the application of photonic crystals in integrated optics. This strongly affects the mode coupling efficiency and the polarization insensitivity We have demonstrated the decrease of impedance in PCs having graded effective index interfaces obtained by modulating the air filling fraction at the input and/or output.