Optical communications involves the transmission of information via optical fibres. Since the use of optical fibres for information transmission became widespread during the 1980s, the pace of technological advances in this area has been astounding. This second edition has been completely updated and revised throughout to reduce much of the mathematics, and to focus on those specific optical technologies that have emerged since the first edition. It presents new material on critical topics in the field, such as digital communications, fibre optics and lightwave networks. The text also integrates both fibre and space optics and emphasizes the systems aspects of optical communications.