ABSTRACT
In this chapter, the authors develop a consistent theory of spontaneous emission in an optical micro cavity from a broadened atom. They derive the atomic broadening from first principles by assuming the presence of reservoirs coupled to the atoms. The simplest model of the atom is the so-called two-level atom, which has only two energy levels, the excited and the ground level. However, realistic atoms are surrounded by media that affect the atoms, giving them homogeneous or inhomogeneous broadening. The important parameter of coupling ratio of spontaneous emission to a desired quasi mode cannot be exactly treated by the present mathematical model of the cavity, although it is easily seen qualitatively that the ratio will decrease with increasing atomic broadening. The authors assume that each atom emits independently and ignored the possible interaction among atoms during spontaneous emission. Solving the master equation for the density matrix elements, the readers have derived formulas for spontaneous emission rate and emission spectrum.
