Quantum cascade lasers start to come of age

AbstractRapid advances of epitaxial growth techniques have opened the possibility for the development of a fundamentally new type of semiconductor devices based on transitions between the subbands in quantum wells and superlattices. One example of such a device is the quantum cascade laser: a fundamentally new light source based on intersubband transitions. This article will report on the recent development of unipolar quantum cascade lasers, which represent a major achievement in the field of solid-state infrared lasers