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An optical fiber sensing system with a frequency shifting loop monitor phase perturbations applied to a transducer in an optical fiber. A sensitivity below 4 µrad/Hz^(1/2) in a 20 kHz – 2 MHz bandwidth is obtained.

Dynamic phase OFDR measurements have been performed up to 8 km by combining a specific tunable laser and an optimized deskew filter post-processing based on a short auxiliary interferometer operated in the coherent regime.

We present a high frequency (500 Hz) and high resolution (sub-50 cm) strain distribution measurement in a 1-km fiber coil excited by a shaker, using a phase-sensitive optical frequency domain reflectometer.