Simulation of Phase Correlation Technique in Brillouin Dynamic Grating Sensors to Achieve Spatial Resolution in the Millimeter Range

The high sensitivity and precision of the distribution optical fiber newfound sensors led to special attention to them and use them in the modern industry, and in particular applications such as monitoring of borders security and leakage of energy pipes, monitoring the safety of large urban structures, Railway lines and so on. The spatial resolution and sensing length are two basic characteristic parameters for researchers. It is obvious that in the military and industrial affairs, whatever the spatial resolution is better will be observed more safety and less damages. The highest obtained spatial resolution between the Brillouin scattering sensors is corresponds to Brillouin dynamic grating sensors which is less than 1 cm. In this sensors, grating was generated by two pump waves and was read by probe wave that senses the intruder. This spatial resolution is achieved using phase correlation technique. In this technique pump waves are modulated by a phase modulator PRBS that generated a periodic and random phase shift equal to 0 or π. Of course, the heavy signal processing and complicated mathematical equations are disadvantages of this technique. In this article, we simulate phase correlation technique using a straightforward matrix relations and calculated first, spatial resolution and then sensing length. finally, with this innovative technique is obtained 9 mm spatial resolution over a  295 m of sensing length and 14 mm spatial resolution over a 460 m of sensing length that is full matching with the results of phase correlation tecnique without having its complexities.