Quantum cascade lasers

Article By:

Malis, Oana Department of Physics, Purdue University, West Lafayette, Indiana.

Last reviewed:2014

DOI:https://doi.org/10.1036/1097-8542.YB140342

A quantum cascade laser is an infrared semiconductor laser in which electrons travel through a series of quantum wells and emit infrared light at wavelengths that depend on the precise dimensions of the wells. Since the invention of the laser in 1960, researchers have been pushing to expand the functionality of lasers into all ranges of the electromagnetic spectrum. Of particular interest are small, compact, and versatile devices that can be used in multiple portable applications. The semiconductor laser diode perfectly fits this description and has enabled applications from laser pointers to optical telecommunications in the visible and near-infrared range. Yet, the mid- to far-infrared range has been harder to conquer. This is mainly due to scarcity of semiconductor materials with suitable optical (band gap) and structural properties. The solution to the band-gap limit was provided in the early 1990s by a team at Bell Laboratories. Using traditional compound semiconductors as building blocks and exploiting the consequences of quantum mechanics, they succeeded in demonstrating a new type of infrared semiconductor laser, the quantum cascade laser (QCL).

The content above is only an excerpt.