Improved localization algorithm for distributed fiber-optic sensor based on merged Michelson-Sagnac interferometer

A novel distributed fiber-optic localization algorithm with high sensitivity and precision based on merged Michelson-Sagnac interferometer is proposed and demonstrated. By performing simple addition and subtraction processing on the two phase differences of the two interferometers, two superimposed signals with a fixed delay can be obtained. The time delay can be calculated by a cross-correlation algorithm. Combined with the polynomial fitting interpolation, the disturbance location resolution is significantly improved. The total sensing distance can reach 120 km, and the localization errors are within +/- 35 m and +/- 160 m in the contact and non-contact disturbance experiment, respectively. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement