A highly sensitive and low-cost sagnac loop based pressure sensor

A pressure sensor based on Sagnac loop using polarization-maintaining photonic crystal fiber operating at 850 nm with much extended measuring range is experimentally demonstrated. We propose a frequency and phase detection technique to enable much extended measurement range comparing with previously proposed schemes. The scheme gives a linear relationship between phase and pressure variation. Experimental results agree well with theoretical predications. The study also shows that operating at 850 nm improves pressure sensitivity by about three times compared with sensors operating at 1550 nm. It enables the use of low-cost and high-speed charge-coupled device interrogator for measurement.