Since its invention in 1962, the semiconductor laser has come a long
way. Advances in material purity and epitaxial growth techniques have
led to a variety of semiconductor lasers covering a wide wavelength
range of 0. 3- 100 ILm. The development during the 1970s of GaAs
semiconductor lasers, emitting in the near-infrared region of 0. 8--0. 9
ILm, resulted in their use for the first generation of optical fiber
communication systems. However, to take advantage of low losses in
silica fibers occurring around 1. 3 and 1. 55 ILm, the emphasis soon
shifted toward long-wavelength semiconductor lasers. The material system
of choice in this wavelength range has been the quaternary alloy
InGaAsP. During the last five years or so, the intense development
effort devoted to InGaAsP lasers has resulted in a technology mature
enough that lightwave transmission systems using InGaAsP lasers are
currently being deployed throughout the world. This book is intended to
provide a comprehensive account of long-wave- length semiconductor
lasers. Particular attention is paid to InGaAsP lasers, although we also
consider semiconductor lasers operating at longer wave- lengths. The
objective is to provide an up-to-date understanding of semicon- ductor
lasers while incorporating recent research results that are not yet
available in the book form. Although InGaAsP lasers are often used as an
example, the basic concepts discussed in this text apply to all
semiconductor lasers, irrespective of their wavelengths.