Efficiency of spontaneous emission from planar microcavities

We use a computational model to investigate the different routes by which power is lost by an optical emitter placed in a microcavity environment. We make a quantitative investigation of the 1/2n(2) model used by many workers in evaluating the fraction of power radiated from a thin film of emitting material. We show the limitations of the 1/2n(2) model, emphasizing the important role of the orientation of the dipole moment of the emitters. Multi-layer systems, involving dielectric Bragg stack reflectors and metal mirrors, are compared for their efficiency in producing useful radiation. We consider both a standard Bragg reflector and the recently developed omni-directional Bragg stack. We show that metal mirrors, although lossy, may still be effective for producing useful radiation from microcavities. We focus our attention on parameters appropriate for organic microcavity light emitting diode structures.