As speeds have increased in long-haul optical fiber transmission systems, limitations on the performance of directly modulated injection lasers have led to a search for external modulators. At the same time, advances in materials growth and processing have made it possible to fabricate practical devices based on novel quantum mechanical effects. One of the most significant of these has been the development of semiconductor multiple-quantum-well (MOW) modulators. A quantum well is a thin (~100-Å) heterostructure of a low band gap material (such as GaAs) sandwiched between two layers of a high band gap material (such as AIGaAs). Wells this thin manifest quantum-mechanical effects in macroscopic ways.
© 1988 Optical Society of AmericaPDF Article