Study On PON System Monitoring Technology Based On Brillouin Scattering

This thesis illustrates the present situation, challenges and developments of the PassiveOptical Network (PON) and analysis the importance of the PON monitoring system. This paperhas a key research on the PON system network monitoring technology based on BrillouinOptical Time Domain Reflectometer (BOTDR).The paper analysis the principle of identifiable fibers and the BOTDR receiving feedbackscattering signals, including the principle of spontaneous brillouin scattering and stimulatedbrillouin scattering and the Brillouin spectrum suffer the influence of the temperature, the strainof optical fiber and the optical fiber doped substances. This paper analysis the principle of PONmonitoring system based BOTDR, which can distinguish the Brillouin spectrum of optical fiberbranch and monitor the link state of the system by adjusting the Brillouin frequency shift of thecorresponding optical fiber. The simulation of the PON system network monitoring technologyin pulse width, filtering the interference signals, increasing users’ number, positioning damagedoptical fiber for monitoring performance shows that BOTDR coherent detection can effectivelyreduce the detector bandwidth, improve the accuracy and the performance of the system,regulate the detection pulse width and balance the accuracy and the length of optical fibermeasuring.Brillouin coherent reception can eliminate the interference of other scattering signal,increase signal strength and improve the signal-to-noise ratio.Slightly overlapping Brillouinscattering spectrum of the adjacent fiber can improve the splitting ratio and increase users’number, BOTDR monitoring can localize damaged optical fiber.PON system monitoring method in this paper can get a high efficiency, good real-time,remote monitoring and high cost performance, which gives the reference for PON systemmonitoring technology research.