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 components management, but they are costly, battery-dependent, and lack fiber identification, and are limited by the operational environment. Manual inspection methods cannot achieve continuous, long-term, distributed, real-time monitoring of optical fibers across regions. In contrast, this paper proposes a passive distributed photonic sensor based on ultra-high 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, multi-point sensing is enabled without disrupting main signals. The ultra-low power NPN trans-impedance 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 multi-channel 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. Experimental results show that within a wireless sensor-to-transceiver distance range of 0 to 2.25 m, suitable for room-sized FTTH service center applications, the photonic sensor offers up to 6 different measurement accuracies, monitoring optical power in the range of −66.67 to 4.74 dBm, with an overall size of 25×12×2 mm3. At a distance of 1.5 m, the sampling rate can reach up to 145 samples per second (Sps).