On the Detecting Bandwidth of Chirped Pulse ϕ-OTDR

作者：Zhigeng Ye, Pengbai Xu, Kunhua Wen, Jun Yang, Yuwen Qin · 发表于：Journal of Lightwave Technology · 年份：2025 · DOI：10.1109/jlt.2025.3628906 · 被引用次数：2 · 研究领域：Advanced Fiber Optic Sensors、Seismic Waves and Analysis、Advanced Fiber Laser Technologies

The previous common understanding of chirped-pulse phase-sensitive optical time-domain reflectometry (CP-ϕOTDR) was that the strain measurement range hinges on precisely matching the detection bandwidth to the chirp bandwidth. Increasing the shot-to-shot measurement range (SSMR) necessarily raises the sampling rate proportionally, posing significant challenges to signal processing and increasing sampling costs. This paper reveals that using only a detection bandwidth equivalent to a portion of the chirp bandwidth can achieve almost the same SSMR, with only a minor difference attributable to the statistical randomness inherent in Rayleigh scattering. Meanwhile, it shows noticeable degradation of sensitivity. The simulations reveal a balance point between detection bandwidth and sensitivity loss. At this balance point, sensitivity loss is threefold while saving one-third of the bandwidth. Beyond this point, further increasing the detection bandwidth yields diminishing sensitivity improvements, whereas reducing the detection bandwidth below this point leads to rapid sensitivity degradation. Experimental validation shifts this balance point to one-fourth, primarily due to measurement deviations. This study provides design guidelines for employing CP-ϕOTDR cost-effectively in large SSMR applications with acceptable sensitivity loss, such as seismic or ocean wave monitoring.