Progress in Optics

A collection of comprehensive reviews in the field of optics. The first article presents a review of recent investifations concerning multiphoton ionization of atoms in intense radiation fields and includes discussions on above threshold ionization, generation of higher-order harmonics of an intense field interacting with a gaseous medium and the role of chaotic dynamics in the interaction of atoms with monochromatic radiation. A tutorial section on chaotic behaviour is also included. The second article presents a review of modern developments regarding properties of light diffracted by gratings. Both a phemonenological treatment and a macroscopic analysis are presented. The following article reviews developments relating to optical amplifiers, especially those which use semiconductors and optical fibres. The article covers the operating principles, fabrication and performance characteristics. The next article reviews recent research on a promising new class of neural networks, the so-called adaptive multilayer optical networks. Although still in the early states of developments, these devices offer the possibility of implementing optical interconnections in three dimensions and they can be functionally equivalent to several thousand chips. The fifth article deals with idealized but rather useful models of some atomic systems, namely two-level and four-level atoms. The analogy between a quantum two-level atom and a classical model consisting of two coupled optical modes is discussed. Extension of these considerations to optical band structure and to four-level systems is also treated. The concluding article deals thoroughly with free electron lasers in a physical way, while minimum attention is paid to organic generalities and mathematical rigour.