Parallel Path Effect-Free Remote Monitoring and Sensing in Live XGS-PON Using Legacy Optical Time Domain Reflectometry

Over decades optical fiber technologies for communications and sensing developed separately. For the purpose of improving communication link reliability optical power level measurement was added to transceiver modules to coarsely detect fiber faults. It was further complemented by optical reflectometry to localize those faults. For the purpose of fiber-optic sensing, which focuses on monitoring of ambient environment, more advanced techniques were developed based on dedicated photonic sensors, fiber sensing and high-end line interrogation units. Recently, we have noticed a new paradigm – the joint communications and sensing, where the fiber-optic infrastructure is not only to be monitored in terms of telecom link diagnosis, but it is also expected to provide detailed information on e.g. temperature, vibration, strain, which can be associated with abnormal activity such as earthquake, fire or intrusion. The optical access network provide great potential for obtaining large volumes of sensing data due to high number of links in the installations. However, these networks are often based on fiber point-to-multipoint architectures comprising optical power splitter, which limits performance of known reflectometry-based supervision originally dedicated to fiber point-to-point links. We present an efficient method for supervision of fiber point-to-multipoint access networks to serve monitoring and sensing purposes. The method is based on an upgraded passive remote node architecture, which realizes reflectometry trace serialization concept. The method enables the application of legacy reflectometers independent from the network protocol and with minimal impact on data transmission.