Monitoring technique for a hybrid PS/WDM-PON by using a tunable OTDR and FBGs

Abstract

A monitoring technique for hybrid passive optical networks (PON) is presented. The technique is based on the remote sensing of fibre Bragg gratings (FBGs) using a tunable optical time domain reflectometer (OTDR). The FBG would help discern an individual event during the monitoring of the hybrid PON in collaboration with the information provided by the Rayleigh backscattered power. The hybrid architecture of passive splitter-PON and WDM-PON can be analysed by the monitoring method by using the tunable OTDR and FBGs at the central office under the in-service state of PON.

Viability of in-service, low-cost and spatially unambiguous OTDR monitoring in TDM- and WDM-PON access networks

“…This strategy has been used in [3] and [4]. Using a single-wavelength OTDR to monitor tree-structured PONs [3] may lead to ambiguity in failure detection, if some of its fibre branches have the same length.…”

“…This strategy has been used in [3] and [4]. Using a single-wavelength OTDR to monitor tree-structured PONs [3] may lead to ambiguity in failure detection, if some of its fibre branches have the same length. Relying on the measurement of attenuation variations of reflective events which are located at the same distance is not a good solution, since aging or upgrading operations can easily change the losses related with the other optical components present in an optical path or if the monitoring signal suffers amplification.…”

Optical layer monitoring in Passive Optical Networks (PONs): A review

“…Each branch is assigned a monitoring wavelength thanks to the already existing presence of the wavelength mux/demux device in the remote node (RN) [43]. Having the same operational principle in mind, research has been devoted to some new interrogation techniques specific to WDM-PONs.…”

Centralized PON Monitoring Scheme Based on Optical Coding

“…And it requires the fiber length of each ONU to be different. A tunable OTDR at the OLT and the wavelength selective reflector placed at each ONU are used to identify the faulty branches [3]. For each wavelength of the tunable OTDR, only one branch contributes to the reflection peak.…”