Fundamentals of Orbital Angular Momentum Beams

Orbital angular momentum (OAM) of electromagnetic waves is a field with a short history of less than thirty years. Recent advances in modern technology have paved the way for the development of systems that can generate OAM beams and have inspired scientists and engineers to investigate the possibility of using OAM in real‐life communications applications. This chapter provides a literature review with a comprehensive list of references on emerging applications of OAM in free‐space optical and RF communications and fiber communications, highlighting potentials and technical challenges. The fundamental properties of OAM beams are revisited by providing in‐depth discussions of the mathematical details and radiation characteristics of OAM beams. Analogies and antitheses are given between conventional and OAM beams regarding the antenna generation methods and the fundamental beam properties and their potential applications in the near field and the far field. This chapter serves as a general introduction to the rest of the book chapters discussing various OAM topics in detail.