Multi-branch identification using Φ-OTDR for PON physical layer monitoring

In this study, we proposed a cost-effective Φ-OTDR system for multi-branch monitoring in passive optical network (PON). The system accurately identified faulty branches in physical layer by analyzing specific identification frequencies (IFs) using piezoelectric transducers (PZTs). Through experiments with various optical splitters (1x2, 1x4, 1x8), we demonstrated the feasibility of the developed system. From the results, the proposed method reliably detected IFs even under significant power attenuation (21 dB) and successfully identified the frequency intervals down to 15 Hz with a maximum range of 2.5 kHz, supporting the simultaneous monitoring of up to 64 branches in PON. The results highlight the system's potential for large-scale deployment in complex PON architectures.