1:45 PM - 2:00 PM
[STT42-01] Towards Long-Reach Distributed Fiber-Optic Sensing Over Active Repeated Subsea Telecom Cables
★Invited Papers
Keywords:Distributed fiber-optic sensing, Optical repeaters
We present a fiber sensing system capable of performing distributed fiber-optic strain sensing over live submarine telecommunication cables. We review a recent demonstration of operation over a ~2000km long subsea cable with ~25 repeaters. In contrast to tradi-tional distributed acoustic sensing (DAS) systems, which are limited to the first span (~50-100km offshore), our prototype is capable of performing distributed measurements over the entire cable length by using high-loss loopack (HLLB) couplers inside the optical repeaters. Despite the ~35dB optical loss from the HLLBs, we achieve a spatial resolution of ~200m for a measurement frequency of about 500Hz over the entire cable.
The system, based on optical frequency domain reflectometry, is inherently compatible with live telecom traffic. We demonstrate this by measuring the performance of multiple telecom transceivers while performing sensing, showing zero outages or performance degradation. The system consists of a telecom-grade optical Tx/Rx front-end, a laser source and an FPGA for signal generation and detection. The receiver-side processing is implemented in real-time using custom FPGA+GPU design. All components used are manufactured in volume and present in state-of-the-art optical and wireless communication systems. This ensures that the system can be scaled and easily manufactured in volume. The powerful combination of FPGA+GPU also enables flexibility and the system can easily be customizable to tackle unique challenges in fiber sensing.
Finally, we discuss system trade-offs and how they can be addressed to realize “DAS”-like measurements over multi-span live subsea cables. We compare the system to alternative methods using fiber gratings to perform per-span sensing with about 50-100km spatial resolution as well as traditional DAS and optical interferometry. Our goal is to provide an overview of the work and engage with the meeting attendees to jointly understand how to tailor system performance to maximize its ability to enhance sensor coverage in the sparsely monitored deep ocean. Applications for this include seismic monitoring/detection, tsunami warning, climate change research and more.
The system, based on optical frequency domain reflectometry, is inherently compatible with live telecom traffic. We demonstrate this by measuring the performance of multiple telecom transceivers while performing sensing, showing zero outages or performance degradation. The system consists of a telecom-grade optical Tx/Rx front-end, a laser source and an FPGA for signal generation and detection. The receiver-side processing is implemented in real-time using custom FPGA+GPU design. All components used are manufactured in volume and present in state-of-the-art optical and wireless communication systems. This ensures that the system can be scaled and easily manufactured in volume. The powerful combination of FPGA+GPU also enables flexibility and the system can easily be customizable to tackle unique challenges in fiber sensing.
Finally, we discuss system trade-offs and how they can be addressed to realize “DAS”-like measurements over multi-span live subsea cables. We compare the system to alternative methods using fiber gratings to perform per-span sensing with about 50-100km spatial resolution as well as traditional DAS and optical interferometry. Our goal is to provide an overview of the work and engage with the meeting attendees to jointly understand how to tailor system performance to maximize its ability to enhance sensor coverage in the sparsely monitored deep ocean. Applications for this include seismic monitoring/detection, tsunami warning, climate change research and more.