Damping of the relaxation resonance in multiple-quantum-well lasers by slow interwell transport

We present a model for quantum-well lasers which for the first time provides an explanation for the increased damping of the relaxation resonance observed in these lasers. Slow transport of holes between the individual wells is shown to lead to a strongly inhomogeneous carrier distribution and to increased damping as well as to RC-like contributions to the modulation response. The model quantitatively explains the differences observed between lasers of varying structure and lasers made from different material systems.