High-spatial-resolution fiber-optic distributed acoustic sensor based on Φ-OFDR with enhanced crosstalk suppression

A high-sensitivity and high-spatial-resolution distributed acoustic sensor based on phase-sensitive optical frequency domain reflectometry ( Φ -OFDR) is proposed. The vibration information is retrieved from the phase change of the complex Rayleigh backscattering. Inner-pulse division and rotating-vector-sum methods are employed to overcome the fading problem and to suppress the crosstalk along the fiber. For the first time, to the best of our knowledge, the waveforms of two simultaneous kilohertz-level vibrations along a 950 m fiber are recovered thanks to the enhanced crosstalk suppression ratio. The spatial resolution of 12 cm and strain resolution of 1 n ε / H z are experimentally achieved.