This volume presents five authoritative review articles on optics and related subjects. The first article deals with important components of many opto-electronic systems, namely waveguide diffraction gratings. It presents an account of the use of waveguide gratings as well as a quantitative review of the properties of optical waveguides. The second article discusses the phenomenon of enhanced backscattering, which has attracted a good deal of attention in recent years. It contains an account of research carried out mainly but not exclusively in the U.S.S.R.. The generation and propagation of ultrashort optical pulses as well as some linear and non-linear effects which arise when such pulses propagate in free space or in material media, is dealt with in the next article. It also includes accounts of the use of ultrashort pulses in the fields of optical communications and data processing. The fourth article presents a brief review of several interferometric methods for overcoming the degradation of image quality caused by atmospheric fluctuations, including the so-called speckle masking method, speckle spectroscopy methods and optical long baseline interferometry with arrays of large telescopes. The concluding article deals with non-linear optical properties of semiconductors and metal crystallites in dielectric matrices. A good understanding of these properties is required when choosing the most appropriate materials for manufacturing devices which utilize several non-linear optical effects. Such devices would be particularly useful in connection with processing and transmission of information and their performance might eventually surpass those of present-day electronics.