This volume presents six review articles devoted to various topics of current interest both in classical and in quantum optics. The first article, by S. Ya. Kilin, entitled "Quanta and Information", is concerned with a multidisciplinary subject which involves optics, information theory, programming and discrete mathematics. The second article, "Optical Solitons in Periodic Media with Resonant and Off-Resonant Nonlinearities", by G. Kurizki, A.E. Kozhekin, T. Optatrny and B. Malomed, reviews the properties of optical solitons in periodic nonlinear media. The article which follows deals with an effect and its inverse which is a manifestation of hindrance and enhancement, respectively, of the evolution of a quantum system by an external agent, such as a detection apparatus. The fourth article discusses the current status of a relatively new branch of physical optics, sometimes called singular optics. The next two articles respectively present a review of advances in two-photon interferometry and their relation to investigations of the foundations of quantum theory and an examination of transverse mode shaping and selection in laser resonators.
