Radiation in spherically symmetric structures. II. Enhancement and inhibition of dipole radiation in a spherical Bragg cavity

Utilizing a classical model, the interaction of a centrally positioned radiating dipole with a finite-sized spherical Bragg structure is treated. A straightforward approach is adopted to calculate the radiative lifetime and resonance frequency shifts of a source within a three-dimensional Bragg structure, and applied to a simple physical system that can be expected to provide a good estimate of the finite-size effects that will occur in more complicated structures. These calculations are of fundamental theoretical interest for understanding dipole-surface interactions, particularly in spherical geometries requiring a vector formulation. The work is of potential practical interest as applied to spherical cavity and photonic structure design, and stresses the connection between recent photonic band-gap research and the earlier investigations of dipole-mirror interactions.