Blue lasers on the horizon

The advantages of semiconductor lasers that produce shorter wavelengths and the underlying physics that make them difficult to achieve are examined. The breakthroughs that have brought a semiconductor laser within reach are described. These include advances in fabricating and doping the large bandgap II-VI semiconducting compounds ZnSe and ZnS on which the new lasers are based and the development of quantum well structures. Integrated design, initial performance, and epitaxial fabrication of the first blue-green emitting laser diode heterostructures are discussed. Some alternative approaches are briefly considered. The problem of developing a contact to connect the laser, or a blue-green light emitting diode based on the same technology, is examined.<>