New Frontiers in Quantum Cascade Lasers and Applications

Recent advances and new directions in quantum cascade (QC) lasers are discussed. Invented in 1994, following many years of research on band-structure engineered semiconductors and devices, grown by Molecular Beam Epitaxy, this fundamentally new laser has rapidly advanced to a leading position among mid-infrared semiconductor lasers in terms of wavelength agility as well as power and temperature performance. Because of the cascaded structure, QC lasers have a slope efficiency proportional to the number of stages. Devices with a hundred stages, having a record peak power of 0.6 W at room temperature are here reported.