Dielectric resonance bandgap and localized defect mode in a periodically ordered metallic-dielectric composite

Dielectric resonance bandgap and localized defect mode in the periodically ordered metallic-dielectric composite networks are investigated by the Green's function formalism. Several band gaps with the zero density of states are shown in the spectrum of dielectric resonances. We find that most of the eigenmodes have an extended field distribution, which is represented by the inverse participation ratio (IPR). Moreover, the defect modes with high values of IPR are fallen into the resonance bandgaps and their positions are very sensitive to the admittance of the defect. The field of these defect modes is very localized around the defect. Finally, we discuss the influence of defect modes to the optical responses.