Addressing the Optical Degradation of 1.3 μm Quantum Dot Lasers through Subthreshold Characterization

We propose a novel methodology capable of separately evaluating the contribution of the different recombination processes in quantum dot laser diodes (QD LDs) driven below-threshold. The proposed approach is based on the analysis of the subthreshold optical characteristics of the devices and was used to evaluate the variation in recombination parameters induced by a long-term stress test. The results of this work indicate that the optical degradation of QD LDs is mainly driven by the increase in the concentration of nonradiative recombination centers within the QWs (quantum wells), with consequent decrease in the injection efficiency. The reported results are of fundamental importance because they demonstrate that conventional models for the extrapolation of the nonradiative lifetime are not capable of reasonably extracting that parameter for LDs featuring a dot-in-a-well-based active region: this limitation is overcome by the reported modeling approach.

Automated summary

We propose a novel methodology to evaluate the contribution of different recombination processes in below-threshold quantum dot laser diodes (QD LDs). The results show that the optical degradation of QD LDs is mainly caused by an increase in the concentration of nonradiative recombination centers, leading to a decrease in injection efficiency. This study is of fundamental importance for improving the design of LDs.