Tight-binding description of the coupled defect modes in three-dimensionalphotonic crystals

We have experimentally observed the eigenmode splitting due to coupling of the evanescent defect modes in three-dimensional photonic crystals. The spl itting was well explained with a theory based on the classical wave analog of the tight-binding (TB) formalism in solid state physics. The experimenta l results were used to extract the TB parameters. A new type of waveguiding in a photonic crystal, was demonstrated experimentally. A complete transmi ssion was achieved throughout the entire waveguiding band. We have also obt ained the dispersion relation for the waveguiding band of the coupled perio dic defects from the transmission-phase measurements and from the TB calcul ations.