Quantum Cascade lasers: Recent advances and future prospects

Quantum cascade (QC) lasers are a rapidly evolving mid-infrared and THz semiconductor laser technology based on intersubband transitions in multiple coupled quantum wells. The lasers´ strengths are their wavelength tailorability, high performance and fascinating design potential. This paper will discuss several recent highlights, such as the quest for high performance QC lasers, especially high efficiency and single-mode operation, artificially broadened gain, and the implementation of unconventional laser schemes. Briefly discussed are several high potential applications in mid-infrared trace chemical sensing.