The demodulation methods for eliminating the impact of the Rayleigh noise in the Raman distributed temperature sensors

Eliminating the Rayleigh noise is of great importance to the Raman distributed temperature sensors. Three simple and effective demodulation methods to eliminate the impact of the Rayleigh noise of the RDTS are proposed. (1) The ratio of the anti-Stokes power to Stokes within the measured temperature range and at the reference temperature (T0) are measured respectively, then the temperature is calculated by the fitting cure of the ratio of Ratio(T) to Ratio(T0). (2) Setting the reference temperature as the median of the measured temperature, the temperature is calculated by the ratio of the intensity of anti-Stokes to Stokes at measured temperature and the reference temperature. (3) Two sections of the reference fiber are utilized to eliminate the impact of Rayleigh noise simultaneously in the Raman distributed temperature sensors using the ratio of anti-Stokes to Stokes. By theoretical analysis and experimental simulation, the proposed measures in this paper can improve the temperature accuracy effectively.