Infrared optical fiber as evanescent wave bio-sensors

Chalcogenide glass optical fibers exhibit a large optical transparency in the mid-IR extending typically from 2 to 22 mu m for the best compositions. Moreover most of these glasses possess unique thermomechanical properties that enable to shape them into optical fibers exhibiting low optical losses from 2 to about 12 gm. Due to their properties, such fibers can be used to implement remote infrared spectroscopy, known as Fiber Evanescent Wave Spectroscopy (FEWS). The glasses and ceramics Laboratory of Rennes have an active research group on this topic since about 4 years leading to interesting results in several fields of application : environment, biology, medicine... In this contribution we would like to focus our attention mainly in the technical choices that have been done to obtain these results, for instance the glass composition, the shape of the optical fiber and the abilities of the sensor.