Effect of guided modes on spontaneous emission in planar microcavities

The spontaneous emission behaviour of a material is influenced by the presence of a microcavity. Time resolved measurements have clearly demonstrated the enhancement of the lifetime for spontaneous recombination in planar-type microcavities.1 In addition, these devices can also exhibit a more directional light emission and a narrower emission spectrum as compared to conventional LED structures. Upon correctly quantizing the electromagnetic (EM) field in the presence of a cavity, one noticed that the spontaneous emission rate is proportional to the electric field strength of the various EM modes at the position of the active material.2 These models give good agreement with experimental results.3,4 In various cases, however, the model does not completely fit the experimental data. This could be explained by the presence of guided modes in the structures, not taken into account by many models. We have developed a model describing the spontaneous emission behaviour including the effect of the guided modes and the reabsorption of light by the active material within planar microcavity structures.