An optical fiber temperature sensor with high sensitivity

An optical fiber temperature sensor with high sensitivity is presented for the measurement of small temperature change in the deep well. The structure of the sensor is an Extrinsic Fabry-Perot Interferometer (EFPI) with two ceramic ferrules inserted into the center from both ends of the aluminum tube. The ceramic ferrules are fixed with screws, and the high strength epoxy resin is used to seal the structure to achieve the effect of waterproof and dust prevention. Aluminum tube and ceramic cores have different thermal expansion coefficients, and the change of temperature will cause the change of EFPI cavity length. Based on the high-sensitive optical fiber white light interferometry(WLI), the temperature can be obtained by measuring the cavity length of the EFPI. The EFPI optical fiber temperature sensor with the cavity length of 146.5μm is continuously measured in a fixed temperature and different temperature. The results show that the sensitivity of the EFPI optical fiber temperature sensor designed has a temperature sensitivity of 260nm/℃, and a temperature resolution of 0.002℃.