The application of distributed optical fiber sensors (BOTDA) to sinkhole monitoring. Review and the case of a damaging sinkhole in the Ebro Valley evaporite karst (NE Spain)

Gutiérrez, Francisco; Sevil, Jorge; Sevillano, Pascual; Preciado-Garbayo, Javier; Martínez, Juan J.; Martín-López, Sonia; González-Herráez, Miguel

doi:10.1016/j.enggeo.2023.107289

Cited by 6 publications

(1 citation statement)

References 34 publications

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“…BFS is monitored to evaluate the physical parameters whose sensitivity for single mode fibers at 1550 nm is ~ 50 MHz/1000 𝜇𝜀 and ~1 MHz/°C. By exploiting the Brillouin scattering phenomenon in optical fibers, BOTDA enables the precise and highly accurate measurement of temperature and/or strain over tens of kilometers of fiber lengths with high spatial resolutions [1], [2], [3] . This capability has found applications in various fields, including structural health monitoring, geophysical exploration, and security sensing [2], [3], [4] .…”

Section: Introductionmentioning

confidence: 99%

Ultra-long-distance BOTDA sensor system employing hybrid amplification and advanced noise reduction technique

Bhatta,

Lalam,

Buric

et al. 2024

Optical Waveguide and Laser Sensors III

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Brillouin optical time domain analysis (BOTDA) sensor systems play a pivotal role in distributed sensing, which enable precise measurements of strain and temperature across extensive fiber lengths. Nonetheless, challenges emerge as distances grow due to signal attenuation and noise interference resulting in measurement errors. This research offers a comprehensive strategy to extend the sensing range of BOTDA systems beyond tens of kilometers while maintaining high spatial resolutions. Such enhanced sensing is realized through hybrid system that employs the integration of distributed Raman amplification, and inline amplification using erbium-doped fiber amplifiers (EDFA), as well as advanced noise reduction techniques. By optimizing power levels for the Brillouin pump and probe signals, as well as for Raman pump, hybrid BOTDA system ensures the robustness of Brillouin scattering signals, effectively countering attenuation-induced losses. Distributed amplification not only conquers attenuation but also suppresses nonlinear effects that could undermine measurement accuracy. Additionally, enhancing weak Brillouin signals by strategically placing EDFAs at optimal fiber locations keeps sensor sensitivity high. Leveraging inherent redundancy in measured data as a function of frequency and fiber distance, the non-local means (NLM) filter removes noise while preserving essential physical information. This approach proves particularly advantageous in BOTDA systems, where accurate measurement of Brillouin scattering signals is paramount for long-range sensing with high spatial resolutions. In summary, this research has shown a holistic exploration of extending BOTDA's distance sensing capabilities up to 150 km with spatial resolutions of 8 meters, and Brillouin frequency shift error of 1 MHz.

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