Abstract

Because of their compactness, low consumption, and the fact they can be manufactured in very large volume at low costs, semiconductor lasers have revolutionized photonics. Near-infrared lasers powered the fiber optics revolution and, by this, enabled the creation of the internet; visible one are ubiquitous in optical pointers and in display elements. For many years, semiconductor lasers were limited to operate in the near-infrared to visible region of the spectrum because of limitations from Auger recombination and material quality for devices that would operate at longer wavelength. The use of new architectures, such as the quantum cascade laser based on intersubband transitions in quantum wells opened a completely novel approach to the semiconductor light generation from the mid-infrared to the terahertz region of the spectrum.

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