I wrote Laser Fundamentals with the idea of simplifying the explanation of how lasers operate. It is designed to be used as a senior-level or first-year graduate student textbook and/or as a reference book. The first draft was written the first time I taught the course “Laser Principles” at the University of Central Florida. Before that, I authored several general laser articles and taught short courses on the subject, giving careful consideration to the sequence in which various topics should be presented. During that period I adjusted the sequence, and I am now convinced that it is the optimal one.
Understanding lasers involves concepts associated with light, viewed either as waves or as photons, and its interaction with matter. I have used the first part of the book to introduce these concepts. Chapters 2 through 6 include fundamental wave properties, such as the solution of the wave equation, polarization, and the interaction of light with dielectric materials, as well as the fundamental quantum properties, including discrete energy levels, emission of radiation, emission broadening (in gases, liquids, and solids), and stimulated emission. The concept of amplification is introduced in Chapter 7, and further properties of laser amplifiers dealing with inversions and pumping are covered in Chapters 8 and 9 [Chapters 8–10 in the Second Edition – Ed.]. Chapter 10  discusses cavity properties associated with both longitudinal and transverse modes, and Chapters 11 and 12 [12 and 13] follow up with Gaussian beams and special laser cavities.