Through the measurement of the static or dynamic changes in Brillouin frequency along the fiber one can realize a distributed fiber sensor for local temperature, strain and vibration over tens or hundreds of kilometers. Brillouin scattering in optical fiber describes the interaction of an electro-magnetic field (photon) with a characteristic density variation of the fiber. By using. This technology enables the fiber optic cable to act as a sensor, providing continuous sensing with wide sensing coverage and advanced warning capabilities in real-time. When the electric field amplitude of an optical beam (so-called pump wave), and another wave is introduced at the downshifted Brillouin.