Study on the distributed fiber optic sensing and locating technology for security system

A new distributed fiber optic perturbation sensing and locating technology based on the Mach-Zehnder (M-Z) interferometers was studied. This technology can be used to detect the perturbation along all fiber in realtime. Based on this technology, a security system was designed, and the locating principle of this system was analyzed. The result of the theoretic analysis and the experiment showed that the measurement sensitivity of the detecting perturbation is greatly improved. Experimenting on the type disturbance's optic cable and forcing on the 18.46 km long distance fiber, the system correctly showed the position in real time and the average location error is 42 m. The experiment showed that the system can be applicable for locating on 26 km distance fiber cable when the power of the laser resource increases to 300 μW.