High-accuracy distributed temperature measurement using difference sensitive-temperature compensation for Raman-based optical fiber sensing.

In the temperature monitoring field, the Raman Distributed Temperature Sensor (R-DTS) is required with a temperature accuracy better than 1 °C over a long distance. This paper proposes and experimentally demonstrates an R-DTS system based on the difference sensitive-temperature compensation to optimize the temperature accuracy with the enhanced temperature sensitivity of backscattered spontaneous Raman scattering. While operating in the experiment, the distributed temperature measurement and theory analysis use the dual-demodulation, self-demodulation and double-end configuration principles for R-DTS are demonstrated. The experimental results show that the temperature accuracy is 12.54 °C, 8.53 °C and 15.00 °C along the 10.8 km under the standard R-DTS systems, respectively. Further, we analyze and recalibrate the intensity of the Raman scattering signal in theory, and substitute the sensitive-temperature factor (M(L)) into the Raman scattering signal. Finally, a novel temperature demodulation method with difference sensitive-temperature compensation is applied to the dual-demodulation, self-demodulation, and double-end configuration R-DTS systems. After compensation, the temperature accuracy can be optimized to 0.38 °C, 0.36 °C and 0.56 °C at the same position. It proves that the proposed method can make the temperature accuracy better than 1 °C for these three demodulation systems.