An RF Passive Distributed Photonic Sensor for Monitoring Unpowered Optical Network Components

Optical power meters for signal strength estimation are widely used in unpowered optical network component (UONC) management, but they are costly and battery-dependent, lack fiber identification, and are limited by the operational environment. Manual inspection methods cannot achieve continuous, long-term, distributed, and real-time monitoring of optical fibers across regions. In contrast, this article proposes a passive distributed photonic sensor based on ultrahigh-frequency (UHF, 860–930 MHz) radio frequency identification (RFID) to achieve real-time optical power monitoring at each node while complying with regional equivalent isotropic radiated power (EIRP) regulations. By tapping a small fraction of optical power through low-ratio splitters, multipoint sensing is enabled without disrupting main signals. The ultralow-power NPN transimpedance amplifier (NPN-TIA) reduces the power consumption by 83.24% during wireless energy harvesting, allowing the system to operate without a battery. The expansion module enables a single photonic sensor to monitor multichannel optical power, achieving hardware multiplexing and scalable deployment. To ensure stable RF communication under temperature and fabrication variation, a tunable impedance-matching circuit is introduced to correct resonance drift. The experimental results show that within a wireless sensor-to-transceiver distance range of 02.25 m, suitable for room-sized FTTH service center applications, the photonic sensor offers up to six different measurement accuracies, monitoring optical power in the range of −66.67 to 4.74 dBm, with an overall size of $25\times 12\times 2$ mm³. At a distance of 1.5 m, the sampling rate can reach up to 145 samples per second (Sps).