A new interferometric and polarimetric temperature optical fiber sensor

Most of interferometric temperature optical fiber sensors (O.F.S.) have a narrow dynamic range. In this paper we present both polarimetric and interferometric temperature O.F.S.. It is a single arm two-waves interferometer using Fresnel reflections at the end faces of the fiber. A controlled birefringence is induced in this fiber by tension coiling around a thermally expandable cylinder. We present a theoretical study of the thermal variations of the mean round phase trip and of the differential phase which is closely related to the induced birefringence. We show that the two waves interferences lead to a high resolution and that a polarization analysis allows a large dynamic range-experimentally, a resolution better than 0.01 °C is demonstrated within a dynamic range of 10°C. Finally the limitations of this sensor are discussed and some improvements of the experimental devices are suggested.