Quantum Cascade Lasers: Theory and Applied Use for Gas Monitoring

The birth of lasers was a scientific revolution that changed the world as we know it. Lasers are critical in areas such as lidar/automated driving, surgical instruments, heat treatment, and spectroscopy. In spectroscopy, the physical limitations of typical laser material previously prevented operation in the infrared. Hence the development of the quantum cascade laser (QCL), a breakthrough that allows lasers to become powerful infrared sources.

Gary Spingarn and Slawomir Piatek discuss the intersection at which infrared gas spectroscopy and QCLs meet. They cover the general physical theory of QCLs, along with distributed feedback structure, laser performance characteristics, the mechanics of laser spectroscopy, and product needs for operation. Topics include: the general physics of QCLs and distributed feedback structure, why QCLs are advantageous for gas monitoring and how measurements are performed, important considerations for comparing QCLs, and market options for getting started.