Light propagation via coupled defects in photonic crystals

Summary from only given. We start from a general form of the reciprocity theorem and derive equations which are linear with respect to the frequency. The equations describe pulse propagation in an arbitrary arrangement of defects in a photonic crystal, with an additional arbitrary but weak perturbative polarization, describing, e.g., a nonlinearity. For a linear chain of uniform defects with two degenerate modes per defect We compare the dispersion relations of one of the two emerging minibands resulting from the tight-binding analysis and rigorous plane wave calculations.