An Ameliorated Positioning Scheme for Optical Fiber Interferometer-Based Vibration Sensors in Perimeter Security Monitoring Application

Optical fiber interferometer vibration sensors demonstrate a distinctive capability to monitor mechanical vibrations across numerous independent points using a multicore fiber cable, making them highly promising for applications in perimeter security monitoring. However, precisely locating vibrations along a long-haul fiber cable remains a significant challenge in these applications. To address this challenge, this article presents and validates an enhanced positioning strategy based on multivariate variational mode decomposition. In contrast to previously reported positioning approaches for long-range interferometer-based vibration sensors, which predominantly rely on demodulating the phase information of the applied vibration to determine the specific locations, the proposed positioning scheme offers notable advantages, including reduced computational complexity, lower hardware costs, and improved positioning accuracy. To validate the effectiveness of the proposed positioning scheme, experiments were conducted to localize vibration events along a 101-km sensing fiber cable using an annular asymmetric dual Mach-Zehnder interferometer-based long-range distributed optical fiber vibration sensing system. The experimental results show an accuracy of 0.026%, corresponding to a mean positioning error of 26.2 m. In addition, the proposed scheme achieves a mean positioning processing time of just 0.379 s. Consequently, we believe that the proposed positioning scheme offers significant potential for long-distance perimeter security monitoring and other related fields that rely on interferometer-based distributed optical fiber vibration sensors.