FIELD QUANTIZATION AND SPONTANEOUS EMISSION IN LOSSLESS DIELECTRIC MULTILAYER STRUCTURES

A complete set of cavity modes in planar dielectric multilayer structu res is presented which naturally includes the guided modes. We show th at most of these orthonormal fields can be derived from a coherent sup erposition of plane waves incident on the stack from the air and from the substrate. Using this set of cavity modes, vie present a quantizat ion scheme in idealized lossless stratified dielectric structures. Thi s enables us to discuss the vacuum quantum fluctuations of the fields within the multilayer stack. The spontaneous emission of photons by a two-level atom located at any position inside the stratified planar st ructure is derived using the quantum approach and standard perturbatio n theory. The spontaneous emission rate as well as the radiation patte rn in the air, in the substrate and in the guided mode are presented. Finally, a numerical analysis of the radiative properties of an erbium atom located in an asymmetrical Fabry-Perot multilayer structure is i nvestigated. We show that a large part of the emitted power is directe d in one half-space although a significant amount of light remains tra pped in the guided modes of the structure.