Abstract
Recently, many groups have succeeded in fabricating artificial inverse opal photonic crystals using inverse opal techniques, Interestingly, it was discovered that an incompletely infiltrated inverse opal has a larger gap than a completely infiltrated opal. We explain this enhancement using a careful mode analysis and perturbation theory basing on a plane wave expansion approach. By examining the field pattern of the normal modes, we see how the normal mode frequencies change after adding or deleting dielectrics at particular locations in the photonic crystal and thereby understand why an incomplete infiltration can enlarge a photonic gap. Furthermore, we also explain the effect of sintering using the same method.