Black glasses, bulk and fibers: Obtaining information in the infrared

Black in the visible but highly transparent in the infrared, the chalcogen-based glasses have reached a maturity which makes them competitive materials for several technological applications related to detection in the mid IR spectral domain. As bulk IR transparent materials they offer an advantage compared to germanium crystals, as they are low cost materials which can be shaped into simple or sophisticated IR lenses by molding. Many efforts have been made to optimize the chemical composition in order to make these glasses very resistant to moisture and oxygen corrosion or devitrification.When drawn into optical fibers with different optical configurations, they represent anew generation of waveguides covering the 3 to 12gtm spectral domain and paving the way for the development of temperature, chemical or bio-chemical sensors. Amongst these possibilities, the remote in situ analysis of chemical processes (such as fermentation or reactions carried out under microwave or autoclave conditions) as well in vivo analysis of biological tissues, are the most exciting. The use of chalcogen glass fiber tips for scanning near field micro-spectroscopy is also a promising field.