Most of the material in this volume is new. The first three chapters deal with three important fiber-optic components--fiber-based gratings, couplers, and interferometers--that serve as the building blocks of lightwave technology. In view of the enormous impact of rare-earth-doped fibers, amplifiers and lasers made by using such fibers are covered in Chapters 4 and 5. The last three chapters describe important applications of nonlinear fiber optics and are devoted to pulse-compression techniques, fiber-optic communication systems, and soliton-based transmission schemes. This volume should serve well the need of the scientific community interested in such fields as ultrafast phenomena, optical amplifiers and lasers, and optical communications. It will also be useful to graduate students as well as scientists and engineers involved in lightwave technology.