Design of Passive Optical Network Monitoring System Based on Optical Frequency Domain Reflectometer using Various Types of Fiber Bragg Gratings

This paper presents a centralized, simple, and cost-effective monitoring system for Point-to-Multipoint (P2MP) Passive Optical Networks (PON) based on the Optical Frequency Domain Reflectometry (OFDR) technique. A 1530 nm Distributed Feedback Laser (DFB) and a Light-Emitting Diode (LED) are evaluated as monitoring sources to assess performance and feasibility for low-cost deployment. Fiber Bragg Gratings (FBGs) with selected Bragg wavelengths and bandwidths are utilized as drop-fiber identifiers to enable customer-level localization and monitoring within the distribution network. The proposed FBG placement follows an OFDR-based configuration, where one FBG is positioned after the monitoring source, while additional FBGs are inserted along the distribution fibers. By leveraging the OFDR concept, the system operates with reduced monitoring source bandwidth requirements and enables the use of a low-cost receiver, implemented using a Radio Frequency (RF) spectrum analyzer. Experimental results demonstrate that the proposed centralized monitoring approach is capable of monitoring up to 32 customers, achieving a minimum downstream received power of − 25 dBm. Overall, the proposed system offers a practical and scalable monitoring solution for PON infrastructure with reduced hardware complexity and lower operational cost.