Modal reflectivity in finite-depth two-dimensional photonic-crystal microcavities

Abstract

We present finite-difference time-domain calculations of the $Q$ factor for an optical microcavity defined by a slab waveguide and two-dimensional photonic-crystal end mirrors. The effect of the finite depth of the photonic crystal on the cavity’s optical modes is examined. From these calculations, we can optimize the performance of the photonic-crystal mirrors and determine the loss mechanisms within optical cavities defined by these structures. The $Q$ of the cavity modes is shown to be strongly dependent on the depth of the holes defining the photonic crystal, as well as the refractive index of the material surrounding the waveguide core.