Forward Transmission Distributed Fiber-Optic Sensing: A Short-Range Demonstration

• Published in: IEEE sensors journal Vol. 25; no. 6; pp. 10243 - 10249
• Main Authors: Liu, Hanjie, Rao, Xing, Dai, Shangwei, Liu, Guoqiang, Zhu, Runlong, Chen, George Y., Wang, Yiping
• Format: Journal Article
• Language: English
• Published: New York IEEE 15.03.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Acoustic sensor; distributed fiber-optic sensor; Fiber optics; forward distributed acoustic sensing (DAS); forward transmission; Frequency ranges; Frequency response; Optical fiber communication; Optical fiber couplers; Optical fiber sensors; Optical fiber theory; Perturbation; Perturbation methods; Phase demodulation; Root-mean-square errors; Sensors; short range; Spatial resolution; Time-domain analysis; Time-frequency analysis; vibration sensor; Vibrations
• ISSN: 1530-437X; 1558-1748
• DOI: 10.1109/JSEN.2025.3537114

The forward-transmission distributed fiber-optic sensing is a cutting-edge technology capable of detecting sounds and vibrations, along with their precise locations, across distances spanning hundreds of kilometers. While much of the existing research has focused on its long-range capabilities, where it offers significant benefits, little attention has been given to explore its performance at shorter ranges and its high-frequency response. Investigating these aspects can provide a more complete understanding of the technology and its comparative effectiveness against traditional methods at various sensing scales. In this work, a forward transmission distributed acoustic/vibration sensing system based on coherent detection using a <inline-formula> <tex-math notation="LaTeX">3\times 3 </tex-math></inline-formula> coupler, arctangent phase demodulation method, and phase-spectrum time-delay method is theoretically simulated and experimentally demonstrated. In particular, the short-range performance of the system is studied when subject to multiple perturbations with short spacing intervals. The 5-kHz single-perturbation experimental results reveal a positioning accuracy of 2.4-m root-mean-square error (RMSE) and 0.5 m [standard deviation (STD)], which is comparable to conventional sensing technologies. The multipoint perturbation tests were performed perturbation events separated by 2 m, across a frequency range of 5-16 kHz. The findings indicate that the system can effectively and reliably identify the perturbation events, for example, located at 500 and 502 m, along a 1004-km-length sensing fiber.