Quality factor for localized defect modes in a photonic crystal slab upon a low-index dielectric substrate

Abstract

Localized defect modes in a two-dimensional photonic crystal slab upon a ${\mathrm{SiO}}_2$ substrate have been analyzed by a numerical simulation of dipole radiation based on the finite-difference time-domain method. A degenerate pair of the defect mode of $E_1$ spatial symmetry was found in a pseudogap in the spectrum of dipole radiation. We achieved a quality factor as large as 800 by optimizing the sample geometry.