Semiconductor lasers are an important light source for fiber-optic communications and are key components of such common appliances as compact disc players, supermarket scanners, laser printers, fax machines, and laser pointers. The lasers in these applications are so-called double heterostructure lasers, essentially diodes consisting of an active semiconductor region sandwiched between doped semiconductor cladding layers, one n-type, the other p-type. The cladding regions supply electrons and holes to the active region when an appropriate bias voltage is applied. They also have a higher bandgap and a lower refractive index than the active layer, so that the injected electrons and holes as well as the photons generated by their annihilation are confined to the active region. The share of the 2000 Nobel Prize in Physics awarded to Zhores Alferov and Herbert Kroemer for their role in developing the double heterostructure laser recognized the major impact of this device (see Physics Today...

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