Spontaneous Emission and the Concept of Effective Area in a Very Short Optical Cavity with Plane-Parallel Dielectric Mirrors

Abstract

Spontaneous emission in a model cavity with very short length and with plane-parallel dielectric mirrors is calculated quantum-mechanically under perturbation approximation. Outgoing modes as well as guided modes are considered. Results on the directivity and the rate of emission into outer space are compared with the estimate by Purcell's method. This leads to the concept of “effective area” of the “cavity mode”, which has a simpie physical interpretation.