Quantum Cascade Lasers for Chemical Sensing
Quantum Cascade lasers are miniscule semiconductor lasers that consist of many atomic layer-thin sheets of two alternating semiconductor materials. The precise thickness sequence of the layers turns the mix of two materials into a new 'designer' laser material that can be engineered to emit light at almost any wavelength in the mid- and long-wave infrared region. In addition the layer structure is designed to provide gain across an especially broad range of wavelengths. A combination of such a Quantum Cascade gain chip and a dispersive external cavity results in widely tunable single frequency emission as required for broad-range chemical sensing capabilities. (Photograph by Frank Wojciechowski.)
