Fundamental Laser Physics

This textbook provides a comprehensive introduction to the principles of laser physics, covering classical, semi-classical, and quantum descriptions of light-matter interaction. Developed from the author’s teaching experience, it presents the fundamental concepts of laser operation, optical radiation, gain mechanisms, and laser dynamics in a coherent and accessible manner. A distinctive feature of the text is its integration of rigorous mathematical derivations with geometric construction methods, bridging mathematical formalism and physical insight and enabling readers to visualize the behavior of optical systems. The book covers topics ranging from coherence and radiation processes to resonant cavities, Gaussian beams, laser pulses, and semiconductor laser diodes. Particular attention is given to laser transitions, line broadening, rate equations, resonator stability, beam propagation, and techniques such as Q-switching and mode locking. Geometrical tools including ABCD matrices, Smith diagrams, and Collins diagrams provide alternative perspectives for understanding laser systems and beam transformations. Exercises throughout the text help reinforce key concepts and develop problem-solving skills. It is intended for advanced undergraduate and graduate students in physics, optics, photonics, and related engineering disciplines. It also serves as a useful reference for researchers seeking a solid foundation in the principles and analytical methods of laser physics.