This book introduces the physical principles of optical fibers, and details their use in sensor technology and modern optical communications.The authors set 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.Throughout the book, physical and engineering aspects of the subject are interwoven, and many worked examples and exercises are included. It will be an ideal textbook for undergraduate or graduate students taking courses in optical fiber communications, photonics, or optoelectronics.