Passive optical access network monitoring using L-band ASE source with fiber Bragg grating

Passive optical access network are becoming denser thus monitoring and fault localization are becoming more crucial. This paper presents optical network monitoring and fault localization using the L-band amplified spontaneous emission (ASE) in Time Division Multiplexing (TDM) Ethernet Passive Optical Network (EPON). A fiber Bragg grating with a distinct center wavelength is placed at each drop fiber before the optical network unit (ONU) in the tree-structured network. The distinct reflected signal from the fiber Bragg grating (FBG) acts as the branch identifier. An optical power meter is used as the receiver to monitor the reflected signal. The system will automatically switch to Optical Time Domain Reflectometer (OTDR) if it detects any breakdown of the drop fiber. This system is capable to monitor up to 64 ONUs with minimum bit error rate (BER) of 10^-9.