Infrared semiconductor lasers for sensing and diagnostics

There is an increasing demand for spectrally agile compact solid-state lasers for spectroscopic sensing and diagnostics. This demand can be met by III–V semiconductor-based lasers employing various design concepts for the active region. These concepts include, apart from the classical type-I interband diode laser, the type-II W-laser and the unipolar quantum cascade laser. Representative device data will be presented for these three types of lasers in conjunction with a discussion of the relative merits of the different active-region concepts.