Room-Temperature External-Cavity Diode Lasers at 2.0 µm

External-cavity diode lasers (ECDLs) have been commercially available for several years. Since their introduction, they have found applications ranging from telecommunications to atomic spectroscopy. These lasers provide a combination of extremely narrow linewidth, broad tunability, and ease of use, making them some of the most versatile lasers available. Until recently, the accessible wavelengths have been limited to the 0.6-1.6-µm region where commercial laser diodes are available. Development conducted by Focused Research, a research subsidiary of New Focus, and Sarnoff Corporation, with support from NASA Goddard Space Flight Center, has extended this range, resulting in the commercialization of the first external-cavity diode laser operating beyond 2.0 µm.