Validation of TW-COTDR method for 25km distributed optical fiber sensing

The paper reports results of the long distance (25 km range) distributed optical fiber sensing by means of Tunable Wavelength Coherent Optical Time Domain Reflectometry (TW-COTDR) method. The tests were designed to verify the accuracy and repeatability of the method in long distance measurements, as well as compatibility with various optical fiber types. Results demonstrate the capability of the method to detect strain or temperature changes over long distances. This proposed method is compared to Brillouin sensing techniques, into the same fibers. Unlike the Brillouin-based methods, measurement uncertainty does not increase with increasing distance. We demonstrated 0.16°C uncertainty at 21km.