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 emission 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 relaxation when doped with rare earth elements. Despite the number of candidates 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 remarkable amplification in the 1.3 mu m region and lasing emission in the blue or mid-IR. Non-linear optical properties of chalcogen-based glasses are also of special interest for fast all optical switching and photo-induced effects. (C) 1999 Elsevier Science Ltd. All rights reserved.