Spectral selective absorption enhancement in photonic crystal defect cavities

In this paper, we present the simulation results on the absorption modification in a two-dimensional photonic crystal slab (2D PCS) structure, based on three-dimensional finite-difference time-domain technique (3D FDTD). Significantly enhanced absorption at defect level was obtained at surface normal direction in a single defect photonic crystal cavity, for both in-plane and vertical sources. An absorption enhancement factor in the range of 100-6,000 was obtained under different operation conditions, based on the normalized absorption power spectral density with respect to the reference slab without photonic crystals. Complete absorption suppression within the photonic bandgap region was also observed in defect-free cavities. High spectral selectivity and tunability was feasible with defect mode engineering.