Abstract

Arguably the most significant advance in the 30-year history of the semiconductor laser was the introduction of the quantum well heterostructure. The attractive features of the physics of the quantum size effect are the basis for the incorporation of these structures in nearly all modern semiconductor laser diodes. Quantum well lasers have lower threshold current density, higher gain, higher efficiency, and in some cases an increased range of available emission wavelengths. Small variations, such as the incorporation of a modest amount of elastically accommodated strain, can result in dramatic changes in the operation of these devices. Although some of the main aspects have been known for many years, quantum well lasers are still the subject of much current research and development. In this tutorial, we describe the basic operating principles of quantum well heterostructure lasers, and outline recent advances in the understanding and application of these remarkable devices.

© 1995 Optical Society of America