Real-time monitoring in passive optical access networks using L-band ASE and varied bandwidth and reflectivity of fiber Bragg gratings

• Point-to-multipoint PON monitoring technique using L-band ASE source is presented.
• FBGs with various bandwidths and reflectivity are used in this monitoring technique.
• An FBG is inserted at each branch and its spectrum is used as the branch identifier.
• One Bragg wavelength is shared by two types of FBGs reflection spectra.
• More customers can be monitored for the limited bandwidth of monitoring source.

This paper presents a passive optical access network monitoring approach using an L-band amplified spontaneous emission source and varied bandwidths, reflectivity and Bragg wavelengths of fiber Bragg gratings (FBGs). In this technique, the reflection spectra of dedicated FBGs are used as the branch identifier to monitor the integrity of the distribution fiber in a point-to-multipoint network. FBGs with different bandwidths, reflectivity and Bragg wavelengths were used to monitor an increased number of optical network units within the limited bandwidth of the monitoring source. Simulations and experimental testing have been conducted to ensure the feasibility of this system. An experimental setup using four FBGs was conducted for different types of splitters. The signal processing to determine the faulty branches is presented. This system is capable of monitoring up to 32 distribution fibers using a limited monitoring source bandwidth of 10.8 nm with a power margin of 2 dB.