Book excerpt: This book reviews techniques used to characterize non-linear optical constants of chalcogenide glasses in bulk or thin films, and presents the properties of many chalcogenide systems. A range of applications of these glasses are surveyed, including ultra-fast switching, optical limiting, second harmonic generation and electro-optic effects. Also addressed are suitability of chalcogenide films in all-optical integrated circuits, fabrication of rib as well as ridge waveguides and of fiber gratings.