Design of photonic crystal optical microcavities

Using the 3-D finite-difference time-domain (FDTD) method, we analyzed various designs of optical microcavities based on a thin semiconductor membrane perforated with a hexagonal lattice of air holes. The microcavities consisted of single or multiple lattice defects formed by increasing or decreasing radii of air holes, thereby producing acceptor or donor-like defect states. The analyzed geometries include single acceptor or donor defects, as well as ring, hexagonal and triangular cavities. Properties of these structures (excluding single donor-type defect) have not been analyzed previously in a slab of finite thickness. Frequencies, quality factors and radiation patterns of localized defect modes were analyzed as a function of parameters of photonic crystal (PC) and defects. Finally, we discuss possible applications of these structures in active or passive optical devices.