Advanced Fault-Monitoring Scheme for Ring-Based Long-Reach Optical Access Networks

This paper presents a novel fiber fault-monitoring system for long-reach optical access networks based on a transmission-reflection analysis approach. By launching an unmodulated continuous-wave optical signal into the feeder ring and measuring the transmitted and reflected/backscattered optical powers, the proposed monitoring scheme is able to detect, identify, and localize any major fault (covering both reflective and nonreflective events) with a good spatial accuracy (≤10 m) and a high detection speed (3 s). Both experimental and simulation results have demonstrated that the proposed system provides fiber monitoring functionality better than that obtained by the conventional methods.