Study On The Low-cost Monitoring Method Of The Optical Link In Optical Access Network

The passive optical network(PON)monitoring technique has been widely concerned in the optical access network(OAN),especially in the PON.As one of the most widely used techniques in PON monitoring,some progresses have been made on the research of the optical time domain reflectometry(OTDR).In this paper,the Rayleigh backscattering theory and the performance indexes of the OTDR has been analyzed.We analyze the cumulative average technology and orthogonal coding technology,and verify this via the MATLAB simulation.Considering the challenges of the PON monitoring system,a novel low-cost solution based dual wavelengths OTDR has been proposed.The proposed scheme accomplishes the fiber fault monitoring by comparing the different wavelengths testing curves,which is achieved by a pair of FBGs placed at the end of each branch.In our scheme,the complete complementary code(CCC)is also utilized to measure multiple wavelengths simultaneously with only one receiver,in addition of the improvement of dynamic range(DR).At last,we have conduct an experiment to verify the performance of this solution.The PON system consisting of 20 km feeder fiber and a 1:16 splitter is investigated by experiments.The experimental results show that the faulty branch can be successfully identified by using our scheme and the DR is 31.6 dB.What is more,we also demonstrate that our scheme can be applied to the multi-stage PON.