The fiber laser, with its humble beginning in the late 1980s, has undergone tremendous development in the past decade or so, transforming itself from a research curiosity to a major force in modern manufacturing. Today, it is revolutionizing our economy by fundamentally changing the way we mark, machine, and process materials on an industrial scale. The recent development of high-power fiber lasers is also fundamentally shaping a wide range of other areas from physical sciences and medicine to geology and space exploration. In the past few years, the tactical deployment of direct energy weapons based on fiber lasers has become a reality.The development of fiber lasers is rooted in a number of technical areas including optical materials, optical waveguide design, nonlinear optics, optical fiber fabrication, and optical characterization, in addition to optical fiber components, and fiber laser design and architecture. No comprehensive in-depth coverage of such diverse topical areas has appeared in a single book. Many important developments have taken place in the past decade in both academia and industry. This book comprehensively covers the basics, technology and applications of fiber lasers including up-to-date developments in both academia and industry and is aimed to serve as both an introduction and research aid for graduate students, engineers, and scientists who are new to this field and also for veterans in the field