Spontaneous emission in emitting-layer-embedded one-dimensional photonic band-gap structures

We show that the spontaneous-emission behavior of an emitter-embedded periodic photonic band-gap (PBG) stack, described in general on the basis of the approximation of dipole emission, can be considerably modified if the macroscopic features of the emitter are considered. We have developed a model which takes into account the optical thickness of the emitter in the usual formalism. The extended model is presented in comparison with the classical dipoleemission model. Some numerical results are given and discussed, by using GaAs-embedded SiO₂/TiO₂-coated quarter-wave stacks as a specific configuration. Our model provides quantitative arguments for optimization of spontaneous-emission power in terms of radiation frequency and emitter localization. It can be directly applied to optimum design of more complex systems, such as multi-emitter-embedded periodic stacks and any other passive structure.