A passive quasi-distributed optical fiber sensor network based on time division multiplexing for remote discrete water level monitoring

Water level monitoring is vital in water resource management, disaster preparedness, and infrastructure integrity. We propose a simple passive self-referenced quasi-distributed optical fiber sensor (OFS) network for precise monitoring. Using time division multiplexing within a lengthy single-line optical time domain reflectometer network connected to a 1×4 optical fiber splitter, the OFS employs sensing probes (flat-cleaved single-mode fibers) of varying lengths. A four-bit binary code signal demodulation then accurately determines the water level. Experiments showed remote-sensing capability of up to 10 km for four discrete water levels while being insensitive to a wide temperature range and power source fluctuations.