ABSTRACT
The application of single-mode fibers (SMF) in sensing external stimuli such as temperature, pressure, acoustic waves, current, magnetic and electric fields, and rotations is a very important and quickly developing activity. The basic arrangement consists in building a Mach –Zehnder interferometer with one SMF in each arm, only one of them being affected by the external stimulus. A temperature or pressure variation will induce a modulation of the phase for the optical wave transmitted through the exposed SMF. In the case of temperature a more detailed study takes into account the effects of strains induced by the difference in thermal expansion coefflcient between the pure-silica regions, the doped-silica regions, and the plastic jackets. The first proposal for polarimetric sensors uses a low intrinsic birefringence fiber wound under tension on an acoustically compliant cylinder. Many of the applications of interferometric fiber optic sensors require multisensor Systems.
