Brillouin optical time domain reflectometry for fast detection of dynamic strain incorporating double-edge technique

TL;DR

This paper demonstrates a novel direct detection BOTDR system capable of fast, distributed dynamic strain sensing with high accuracy and spatial resolution, using innovative double-edge, time-division multiplexing, and upconversion techniques.

Contribution

It introduces a new direct detection BOTDR method that integrates double-edge, time-division multiplexing, and upconversion techniques for improved dynamic strain detection.

Findings

Detected dynamic strain up to 1.9mε over 1.5 km fiber

Achieved 30 μϵ measurement accuracy

Realized 0.6 m spatial resolution

Abstract

For the first time, a direct detection BOTDR is demonstrated for distributed dynamic strain sensing incorporating double-edge technique, time-division multiplexing technique and upconversion technique. The double edges are realized by using the transmission curve and reflection curve of an all-fiber Fabry-Perot interferometer (FPI). Benefiting from the low loss of the fiber at, the time-division multiplexing technique is performed to realize the double-edge technique by using only a single-channel FPI and only one piece of a detector. In order to detect the weak spontaneous Brillouin backscattering signal efficiently, a fiber-coupled upconversion detector is adopted to upconvert the backscattering signal at 1548.1 nm to 863 nm, which is detected by a Si-APD finally. In the experiment, dynamic strain disturbance up to 1.9m{\epsilon} over 1.5 km of polarization maintaining fiber is detected at a sampling rate of 30 Hz. An accuracy of 30{\mu}{\epsilon} and spatial resolution of 0.6 m is realized.