Carbonaceous substances exhibit optical signatures in the infrared range, between 2 and 12 µm, due to light absorption by the vibrational modes of C-X entities (X=H, O, etc.). Their detection, particularly in confined spaces or remote areas, can be achieved using optical fibers. These bring the light signal into contact with the substance to be analyzed, and return information about its chemical composition.
Conventional silica fibers are only transparent up to 3 µm, making them unsuitable for this application. Fibers based on chalcogenide glasses (S, Se, Te), on the other hand, offer a wide transmission spectrum, from the visible to 12-15 µm in the infrared. Sensors using chalcogenide fibers have been developed for infrared detection of a wide range of substances (CO2, amides, alcohols, pathogens, etc.) of interest in the fields of health, biology and the environment.
