Laser advance could open up new markets

Applied scientists from Harvard University have, for the first time, demonstrated high-power continuous wave (cw) room-temperature quantum cascade (QC) lasers made by a well-established mass production semiconductor synthesis technique. The breakthrough could soon lead to the large-scale commercialization of QC lasers and open up new markets for laser-based chemical sensors.

The new generation of QC lasers relies on a layer deposition technique known as Metallorganic Vapor Phase Epitaxy (MOVPE), one of the most common and versatile methods for mass-producing technology for semiconductor lasers, circuits, and other photonics components for communications.

“By pulling together complementary strengths in the quantum design of QC lasers and in MOVPE technology, the team has achieved record performance that will enable a wide range of commercial and military applications,” said Federico Capasso, Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at Harvard’s Division of Engineering and Applied Sciences.

Quantum cascade lasers were invented and first demonstrated by Capasso and his group at Bell Labs in 1994. These powerful and portable lasers are made by stacking ultrathin atomic layers of semiconductor materials on top of each other, traditionally using a growth technique called Molecular Beam Epitaxy (MBE). By varying the thickness of the layers, scientists can select the wavelength at which a QC laser will emit light, custom designing it for a specific application. The range of applications of QC laser-based chemical sensors is very broad, including pollution monitoring, medical diagnostics such as breath analysis, and applications for homeland security.