A revision of the senior/graduate level text for courses dealing with the theory and application of Optical Fiber Communication Technology, this book progresses from descriptions of the individual elements of an optical communications system to an analysis of system design and ends with discussions of measurement techniques for evaluating components and systems. This edition adds a chapter on systems, new sections on Model Noise, single-mode fibers, and LED-to-made fiber coupling. The book maintains its emphasis on practical design considerations throughout.