A Princeton-led team of researchers has discovered a new mechanism to make common electronic materials emit laser beams. The finding could lead to lasers that operate more efficiently and at higher temperatures than existing devices, and lead to applications in environmental monitoring and medical diagnostics.
The laser in the Princeton study is called a quantum cascade laser. The device, about one-tenth as thick as a human hair and 3mm long, comprises hundreds of layers of different semiconductor materials. In this laser, electrons 'cascade' down through the layers as they lose energy and give off synchronized photons. Unlike other lasers, quantum cascade lasers operate in the mid- and far-infrared range, and can be used to detect even minute traces of water vapor, ammonia, nitrogen oxides, and other gases that absorb infrared light.
"This discovery provides a new insight into the physics of lasers," said Claire Gmachl, an electrical engineer and director of the Mid-Infrared Technologies for Health and the Environment (MIRTHE) center, who led the study. Gmachl's group discovered that a quantum cascade laser they had built generated a second beam with very unusual properties, including the need for less electrical power than the conventional beam.
