Infrared glasses

Driven by applications in hot fields such as optical communications, lasers , sensors, etc. infrared glasses have to be considered as key components in the development of devices for telecom signal amplification, fibre-laser e mission as well as for passive functions related to IR remote spectroscopy or thermal imaging. Stable vitreous materials with low-phonon energies are found in the family of fluorides and chalcogenides glasses; they offer the advantage of excellent transparency in the mid-IR and weak nonradiative rel axation when doped with rare earth elements. Despite the number of candidat es only a very limited number of glass compositions can be shaped into good optical waveguides such as channel or fibre. When possible, this led to re markable amplification in the 1.3 mu m region and lasing emission in the bl ue or mid-IR. Non-linear optical properties of chalcogen-based glasses are also of special interest for fast all optical switching and photo-induced e ffects. (C) 1999 Elsevier Science Ltd. All rights reserved.