Quantum cascade lasers

Summary form only given. This tutorial will emphasize the underlying physics, design principles and performance of quantum cascade (QC) lasers based on intersubband transitions. Recent results on high-resolution spectroscopy will be presented and applications to chemical sensors for trace gas analysis with part per billion sensitivities in areas such as pollution monitoring, medical and combustion diagnostics will be discussed. The last part of the tutorial will summarize alternative QC laser structures based on interband transitions.