ABSTRACT
In this chapter, a brief history of the development of semiconductor lasers will be given. The basic concept of absorption and emission processes will be presented by considering the interaction of light with a two-level atomic system, and the working principle of a laser will be explained. The semiconductor laser and its structure, principle of operation, threshold current density, and power output will be introduced. After a discussion of the usual structures and the need for their use, the materials issue will be addressed. Finally, some of the application areas of semiconductor lasers will be presented.
