Contents I. Introduction
Over the last decade, the advent of microstructured fibers has given rise to new proposals of optical fiber sensors. In particular, chemical sensors have been proposed that take advantage of the possible penetration of gas or liquids into the numerous holes surrounding the core that guides the optical signal [1]. In the case of a solid core, the interaction of the evanescent wave with the introduced chemicals can be monitored through a specific transduction mechanism. Over the last few years, our group has developed a distributed polarimetric sensor that can detect moving coupling points and can then be used for a new type of gas chromatography monitoring [2]. The special fiber is not a true micro structured fiber, but its fabrication benefits from the same technology as it involves a large 100- m hole that runs along the fiber length, next to a polarization-maintaining elliptical core; this hole serves as the column for the chromatography process. Due to the close proximity of the core, the local absorption of a moving vapor by the so-called stationary phase (a special thin polymer layer (PDMS) deposited on the inner wall of the capillary) gives rise to a local rotation of the polarization axes; although being small, the rotation can be easily detected by polarization interferometry [2].
