High-performance distributed dynamic strain sensing by synthesizing φ-OTDR and BOTDR.

We propose and demonstrate a high-performance distributed dynamic absolute strain sensing technique by synthesizing φ-OTDR and BOTDR. The technique synthesizes the relative strain obtained by the φ-OTDR part and the initial strain offset estimated by fitting the relative strain with the absolute strain signal from the BOTDR part. As a result, it provides not only the characteristics of high sensing accuracy and high sampling rate like φ-OTDR, but also the absolute strain measurement and the large sensing dynamic range like BOTDR. The experiment results indicate the proposed technique can realize the distributed dynamic absolute strain sensing with a sensing dynamic range of over 2500 µÉ›, a peak-to-peak amplitude of 1165 µÉ›, and a wide frequency response range from 0.1 to over 30 Hz over a sensing range of about 1 km.