Based On Gated Raman Amplification Method Applying To The Phase-sensitive Optical Time-domain Reflectometer System

Distributed optical fiber sensor(DOFS) can be used as the sensing medium and transmission medium at the same time. compared with other sensors, distributed optical fiber sensor has its unique advantages, and more and more papers is published in this area. Phase sensitive optical time-domain reflectometer(Φ- OTDR),as one popular technology, using optical pulse in optical fiber Rayleigh scattering effects, can real-time get every bit of small disturbance signal. In the area such as the perimeter security,seismic wave detection, and pipeline safety monitoring applications Φ- OTDR has very prominent advantages.This paper contrast the amplification technology in Φ-OTDR system, and put forward a theory by using optical fiber media in different wavelength optical fiber transmission speed difference, realizing pulse Raman amplification. It can reduce the nonlinear effect,improve the SNR of the system and the optimization of system performance.Following works are the authors main contribution:(1) based on Φ- OTDR is comparative analysis of the principle of distributed optical fiber sensing technology, analyzed the theories and the key factors influencing the performances of sensing system, at the same time comparative analysis which are commonly used to optical amplification technology principle.(2) the group velocity dispersion phenomenon is used to realize the pulse Raman amplification, which improved the system signal-to-noise ratio. A based on pulse Raman amplification Φ- OTDR distributed optical fiber sensing system is built(3) realizing a Φ- OTDR system sensing distance of 50 km and the spatial resolution of20 m. proved that using pulse Raman amplification technology is better than continuous Raman amplification way.(4) Complete system hardware device setup and engineering practice.