Rate equation modeling of current injection efficiency in 1.3-μm InAs-InGaAs quantum dot lasers

摘要

Cavity length vs. inverse of slope efficiency technique is most widely used to extract the injection efficiency in semiconductor lasers which assumes that all the carriers occupy single energy level in the laser active region. However, QD lasers contain multiple higher lying energy levels in addition to the ground level and have significant carrier capture times which results in the occupation of these higher energy levels. In addition to the multiple energy levels, the density of states of each energy level is inhomogeneously broadened, which leads to the broadening of the gain spectrum as a whole. Inhomogeneous broadening is a result of the random size distribution of QDs grown by the self-assembled growth technique. In this work, we present the results of an above threshold multi-level rate equation model developed to understand the effect of inhomogeneous broadening on the measured low injection efficiencies of InAs-InGaAs based quantum-dot (QD) lasers operating at 1.3 μm.