High-Resolution Distributed Acoustic Sensor and its Applications in Mechanical Engineering

The past decade has witnessed rapid adoption of distributed acoustic sensor (DAS) technology in various fields from geophysical sciences [1] to railway track behaviour analysis [2]. Limited by the intensity of the Rayleigh backscattering, DAS technology has been mainly adopted for mapping phenomena such as earthquakes or rail traffic that do not require high spatial resolution. Recently, we have developed a new optical fibre that allows an order of magnitude improvement in the spatial resolution of DAS systems. Using this fibre, which we dubbed Ultra Low-loss Enhanced Backreflection (ULEB) fibre, we have demonstrated a DAS with 10 cm spatial resolution and an amplitude spectral density of $1.9\ \mathrm{n}\varepsilon/\surd \text{Hz}$ [3].