Localized defect states in two-dimensional photonic crystal slab waveguides: A simple model based upon symmetry analysis

Localized defect regions within two-dimensional photonic crystal slab waveguides are an attractive method of forming high-quality factor optical resonators with wavelength-scale modal volumes. Using simple symmetry bases, and the tools of group theory, we develop an approximate description of the resonant modes of different photonic crystal defect cavities. Comparison to numerical simulations as well as photoluminescence measurements of actual microfabricated devices demonstrates the power of this modest symmetry analysis in describing the localized defect states within photonic crystals.