Characterization of semiconductor lasers by spontaneous emission measurements

The measurement of spontaneous emission is a powerful characterization technique of semiconductor lasers, which has been developed with the fabrication of the first lasers. It allows the determination of both material and structural parameters such as gain, refractive index, longitudinal effects, etc. Significant advance has been made recently on the understanding of material properties and lasing characteristics by using spontaneous emission measurements. In particular, the effect of spatial hole burning in phase-shifted distributed feedback lasers has been investigated quantitatively. The main origins of the gain suppression in both bulk and quantum-well structures have been identified by observing the evolution of spontaneous emission spectrum with output power. The paper presents the underlying principles of such a technique and gives a summary of these recent achievements as well as the main results.