An optical fiber-folded distributed temperature sensor based on Raman backscattering

A temperature sensor is presented, which is based on optical fiber-folded distributed feedback and Raman backscattering. In the proposed configuration, different locations of optical fiber are put in the same environment to sense the same temperature. The proposed method and traditional method are used to demodulate different temperature fields. By comparing the demodulating results, two main problems have been solved. First, differential attenuation in the traditional method is eliminated between anti-Stokes and Stokes signal when they propagate along the fiber. Second, localized changes in the Stokes are removed, which is caused by other external factors except for the temperature. Furthermore, the detected signal consists of anti-Stokes only, which greatly simplifies the experimental device system. The proposed method has been verified by theoretical simulation to be simple and auto-correct.