Bi-Directional Structure-Based Forward Transmission Distributed Vibration Sensor Utilizing Single Optical Fiber

A single-fiber forward transmission distributed vibration sensor (SF-FTDVS) is proposed in this article based on bi-directional structure, which breaks the dependence of traditional FTDVS on the interference loop structure or the multifiber optical path. The proposed SF-FTDVS inherits the advantages of fiber sensors with forward transmission. It can realize the relay-free distributed vibration sensing greater than 210 km since the continuous forward transmission of light waves provides good signal-to-noise ratio (SNR) performance. Besides, the bidirectional transmission structure enhances the consistency of vibration event perception, so that it can achieve a more precise location. Experiments demonstrated the feasibility of vibration event location with a wide-frequency range from 400 Hz to 10 kHz, allowing for an un-repeated sensing link up to 212 km. To the best of our knowledge, this represents the longest perception distance achieved by a relay-free sensor. The average location standard deviation (STD) and the location fluctuation range are estimated to be 15.7 m and ±37 m, respectively, demonstrating an improvement of 14% and 12% compared to the traditional distributed vibration sensors (DVS) scheme. The proposed SF-FTDVS not only offers the advantages of simple deployment, high-positioning accuracy, and wide vibration response bandwidth, but also exhibits good compatibility with other components, demonstrating great potential for applications in Internet of Things (IoT) systems.