Defect modes merging in one-dimensional photonic crystals with multiple single-negative material defects

Twin defect modes are found to merge into each other in one-dimensional photonic crystals consisting of periodic layers of single-negative (permittivity- or permeability-negative) materials and multiple single-negative defect layers. By increasing the size or the number of the defects, the two defect modes both approach to the middle of the forbidden band gap, then merge when the photonic structure becomes nihility. In addition, the electric fields at the central frequency of the band gap could be designed to be strongly localized at just one interface between the defect layers and the periodic layers of the photonic crystal with low transmission. (c) 2008 American Institute of Physics.