kvantekaskadelaser

A kvantekaskadelaser, often referred to as a quantum cascade laser (QCL), is a semiconductor laser that emits infrared light. Unlike traditional diode lasers which rely on interband electron transitions, QCLs utilize intersubband transitions within the conduction band of a specially engineered semiconductor heterostructure. This structure consists of multiple layers of different semiconductor materials grown with atomic precision, creating a series of potential wells.

The name "quantum cascade" arises from the process where a single electron traverses these layers, emitting a photon at each transition between energy subbands within the conduction band. After emitting a photon, the electron "cascades" down to the next well and repeats the process. This unique mechanism allows for the emission of photons with energies determined by the layer thicknesses and compositions, rather than the material's bandgap, offering significant design flexibility.

QCLs can be engineered to emit light at specific wavelengths across a broad range of the infrared spectrum, from mid-infrared to far-infrared (terahertz). This tunability makes them highly valuable for applications such as gas sensing, spectroscopy, medical diagnostics, and free-space optical communications. Their ability to operate at room temperature and their compact size further contribute to their growing importance in various scientific and industrial fields. The precise control over emitted wavelength is a key advantage over other infrared sources.