H. G. Unger 
Introduction to Quantum Electronics [PDF ebook] 
International Series of Monographs in Natural Philosophy

Introduction to Quantum Electronics is based on a one-semester lecture of electrical engineering for German students. The book is an introduction to the fundamentals of lasers and masers and a presentation of the principles of physics, their theory, and methods of analysis that seek to analyze, explain, and quantify related important phenomena. The properties of a laser is then discussed, the author comparing it to the properties of the maser. Although masers are based on the same physical properties as that of the lasers, masers amplify microwaves by induced emission. How the laser is amplified, its power and frequency of oscillation, and which media are suitable for lasers are analyzed. Descriptions of the laser take more emphasis as it is considered to have more technical applications than the maser. An example given is the operation of the gas laser, because it exhibits coherence in time and space, considered as the most important quality of laser beams. Physicists, students, and academicians in the field of electrical engineering and quantum electronics will find that this book addresses many of their interests.