Beam and Fiber Optics discusses the concepts of wave and geometrical optics that are most relevant to a deeper understanding of beam optics. This book is organized into five chapters that provide the necessary algebraic details, particularly the laws of beam propagation through unaberrated optical systems. The first chapter presents a broad view of the subject matter and a comparison between the laws of mechanics and the laws of optics. Chapter 2 explores the laws of propagation of Gaussian beams through freespace, unaberrated lenses, or lenslike media and resonators. The simplest configurations (two-dimensional with isotropic media) are first considered, but a few advanced problems are also treated. This chapter also discusses the use of Gaussian beams at millimeter wavelengths. In Chapter 3, various wave equations relevant to beam optics are given, and their relationship is examined. This text also emphasizes the importance of the Lorentz reciprocity theorem for problems of coupling between beams or fibers. The geometrical optics limit of wave equations is addressed in Chapter 4. This chapter also considers the propagation of optical pulses in dispersive inhomogeneous (graded-index) fibers based on the point of view of Hamiltonian optics. The final chapter is devoted to piecewise homogeneous dielectric waveguides, such as the dielectric slab and the dielectric rod. A method to evaluate the bending loss of open waveguides is described. This book will be useful to students, professors, and research engineers in the field of electromagnetic communication.