CARRIER TRANSPORT EFFECTS IN QUANTUM-WELL LASERS - AN OVERVIEW

Early theoretical predictions and later experimental work have shown t hat lasers with quantum well active areas have enhanced differential g ain over bulk lasers. The resonance frequency in a semiconductor laser is proportional to the square root of the differential gain. The reso nance frequency is directly related to the modulation bandwidth, and t he enhancement in the intrinsic differential gain led to theoretical p redictions of increased modulation bandwidth in quantum well lasers. T his enhancement in the modulation bandwidth proved to be elusive initi ally, and later it was realized that other factors, namely carrier tra nsport effects, played a more dominant role in the high-speed properti es of quantum well lasers. Carrier transport effects, in addition to b andfilling, affect a wide range of static and dynamic properties of th e quantum well lasers. This paper will present an overview of our pres ent understanding of the carrier transport processes and their effects in quantum well lasers.