Anomalous above-threshold spontaneous emission in gain-guided vertical cavity surface emitting lasers.

Abstract

Anomalously large decrease of spontaneous emission is observed for the first time in gain-guided vertical-cavity surface-emitting lasers after the onset of lasing. We attribute this unexpected phenomenon to the contraction of lasing mode by thermal lensing. two-dimensional profiles of the lasing mode and carrier density are measured. It is found that, above threshold, the carrier density decreases in contradiction to the general understanding, under the condition of the constant modal gain.