Abstract

The mid-infrared and far-infrared regions of the spectrum (3–300 μm) for a long time did not realize its full potential, scientifically and technologically, notwithstanding its paramount importance for chemistry, spectroscopy and a myriad of potential applications, mainly because of the lack of a compact, room temperature, widely tunable and eye-safe laser. This situation drastically changed with the advent of the Quantum Cascade Laser (QCL) in 1994 and its subsequent momentous development in the following two decades [1–4]. I will highlight the fundamentally different design principles and underlying physics of QCLs, which showcase a rich variety of optical and transport phenomena. I will illustrate the impact of QCLs in spectroscopy, chemical physics and atmospheric chemistry and technology, present and future, ranging from IR countermeasures to a wide range of sensor applications including health care, the environment, security and, ultimately, the “internet of everything”.

© 2016 Optical Society of America