Influences of pulse on the performance of phase-sensitivity OTDR

The influences of pulse, including the pulse width Tp and the peak pulse power Ipeak, 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 fluctuations ratio coefficient (FRC) as well as visibility of interferential Rayleigh backscattering light. The simulation results show that the method of amplifying Ipeak is benefit for increasing the FRC induced by vibration, while it is useless for improving the visibility. In contrast, the method of broadening Tp is useful for increasing the FRC by improving the visibility. Laboratory experiments are implemented by using the 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.