Cross-correlation Location Method Used in Sagnac/Mach-Zehnder Interferometer for Distributed Disturbance Sensing

摘要

We present a novel cross-correlation location method to determine a disturbance position in a Sagnac/MachZehnder interferometer. The interferometer is a combination of a Mach-Zehnder interferometer and a Sagnac interferometer by sharing a same sensing fiber. It is verified numerically that the outputs of the Sagnac interferometer and Mach-Zehnder interferometer are cross-correlative when the disturbance amplitude is small. A disturbance position can be determined from cross-correlation of the two interference signals. The effectiveness of the location method is demonstrated experimentally by a prototype system with a sensing fiber length of about 300 meters. An average relative location error of 3.4% is obtained. The experimental results show that the crosscorrelation method is feasible and effective used in a Sagnac/Mach-Zehnder interferometer for disturbance location.