Recent advances in the development of low-loss optical fibers have revolutionized the field of telecommunications, and fiber-based networks form a key part of international communications systems. This book introduces the physical principles of optical fibers, and details their use in sensor technology and modern optical communication systems. The authors begin by setting out the basic propagation characteristics of single mode and multimode optical fibers. In later chapters they cover optical sources, optical detectors, and fiber-optic communication system design. They also treat a wide variety of related topics such as doped fiber amplifiers, dispersion compensation, fiber sensors, and measurement techniques for the characterization of optical fibers. The book emphasizes physical and engineering aspects of the subject. It will be an ideal textbook for undergraduate or graduate students taking courses in optical fiber communications, photonics, or optoelectronics.