Spontaneous emission and optical gain in a Fabry–Perot microcavity

Abstract

The Fabry–Perot microcavity is analyzed in terms of its modification of the spontaneous emission and stimulated emission from a thin gain medium, which is contained between distributed Bragg reflectors. The structures correspond to the vertical-cavity surface-emitting semiconductor laser. Gain enhancement due to the cavity is calculated and compared to the case of a large Fabry–Perot cavity. The critical parameters in determining the degree of gain enhancement are the (large cavity) coherence length of the spontaneously emitted wave packet, and reflector design.