Demonstration of Liquid Pressure Fiber Sensing Based on Distributed Polarization Crosstalk Analysis

The feasibility of a liquid pressure fiber sensing system based on the polarization crosstalk analysis technique through the water depth measurement is experimentally demonstrated for the first time to the best of the authors' knowledge. A specialty fiber sensing tape which contains the polarization maintaining fiber (PMF) sensing medium and a high sensitive sensing unit is designed. The sensing unit can convert the liquid pressure into the crosstalk intensity which can be measured by the polarization crosstalk analyzer precisely. A good linear relationship is obtained in a water depth measuring range of 180 cm through linearly fitting the experimental data, and the goodness of fit is as high as 0.99278. The sensitivity of the proposed fiber sensing system is 0.05374 dB/cm. Future work should be focused on the realization of large-depth sensing with multiple sensing units as well as performing the liquid stratification measurement.