Abstract

Quantum cascade lasers (QCLs) are unipolar mid- to far-infrared semiconductor lasers in which the laser transition occurs between quantized conduction-band states in a series of coupled quantum wells. Typically several tens of active regions connected by injectors are cascaded. A minigap opening up in the injector acting as a Bragg reflector confines electrons in the initial state of the laser transition of the active region.

© 2002 Optical Society of America