Influences of pulse on phase-sensitivity optical time domain reflectometer based distributed vibration sensor

The influences of pulse, including the pulse width T_p and the peak pulse power I_peak, on phase-sensitivity optical time-domain reflectometer (φ-OTDR) based distributed vibration sensor are investigated in this paper. A numerical simulation is performed to illustrate the relationships between pulse and temporal response trace as well as the visibility of interferential Rayleigh backscattering light. The simulation results show that the method of amplifying I_peak is benefit for increasing the amplitude of temporal response trace, while it is useless for improving the visibility. In contrast, the method of broadening T_p is useful for increasing the amplitude of temporal response trace by improving the visibility. Laboratory experiments are implemented by using a φ-OTDR prototype with an electro-dynamic vibration table producing stable vibration signals. The good agreement of experimental with simulated results validates the theoretical analysis.