Laser Fundamentals provides a clear and comprehensive introduction to the physical and engineering principles of laser operation and design. Simple explanations, based throughout on key underlying concepts, lead the reader logically from the basics of laser action to advanced topics in laser physics and engineering. In addition to many improvements to the text and figures of the first edition, much new material has been added to this second edition - especially in the areas of solid-state lasers, semiconductor lasers, and laser cavities. This edition contains a new chapter on laser operation above threshold, including extensive discussion of laser amplifiers. It also provides details on new types of lasers (e.g., Nd:YLF, Nd:YVO[subscript 4], and Yb:YAG) plus a new section on diode pumping of solid-state lasers. The coverage extends to the four basic categories (GaAs, InP, ZnSe, and GaN) of semiconductor lasers. The analysis is applied to electron and hole concentrations for both heterojunction semiconductor lasers and quantum-well lasers, and a thorough discussion of laser cavities features ABCD matrix analysis of two-, three-, and four-mirror cavities. The book first develops the fundamental wave and quantum properties of light, such as coherence, energy levels, emission line width, and stimulated emission. It then uses those properties to develop the concepts of population inversion, gain, saturation intensity, laser operation above threshold, excitation or pumping, and cavity properties, which include longitudinal and transverse modes, Gaussian beams, unstable resonators, Q-switching, and mode-locking. The book addresses aspects that are common to all laser amplification. It examines the development of population inversions in such low-density materials as gases and plasmas as well as in the usual three- or four-level systems of such high-density materials as liquids and solids. Included are extensive accounts of both solid-state and semiconductor lasers, and detailed descriptions and data tables of the most common lasers are provided. The book concludes with a chapter on nonlinear frequency conversion as it relates to lasers. The clear explanations, worked examples, and many homework problems make this book eminently suitable for undergraduate and first-year graduate students in science and engineering who are taking courses on lasers. The summaries of key types of lasers, the use of many unique theoretical descriptions, and the chapter-by-chapter bibliography make this an invaluable reference work for researchers as well.