A distributed vibration sensing technique using double-optical-pulse based on phase-sensitive optical time-domain reflectometry (φ-OTDR) and an ultraweak fiber Bragg grating (UWFBG) array is proposed for the first time. The single-mode sensing fiber is integrated with the UWFBG array that has uniform spatial interval and ultraweak reflectivity. The relatively high reflectivity of the UWFBG, compared with the Rayleigh scattering, gains a high signal-to-noise ratio for the signal, which can make the system achieve the maximum detectable frequency limited by the round-trip time of the probe pulse in fiber. A corresponding experimental φ-OTDR system with a 4.5 km sensing fiber integrated with the UWFBG array was setup for the evaluation of the system performance. Distributed vibration sensing is successfully realized with spatial resolution of 50 m. The sensing range of the vibration frequency can cover from 3 Hz to 9 kHz.
Bibliographical noteTao Liu, Feng Wang, Xuping Zhang, Lin Zhang, Quan Yuan, Yu Liu, Zhijun Yan, "Phase sensitive distributed vibration sensing based on ultraweak fiber Bragg grating array using double-pulse," Optical Engineering 56(8), 084104 (19 August 2017).
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- optical fiber sensors
- optical time-domain reflectometry
- ultraweak fiber Bragg grating
- vibration measurement