Quasi-static pressure sensitivity of single-mode optical fibers

We report on characterizations of standard single mode optical fibers sensitivity to pressure. We used an unbalanced Michelson interferometer, whose long arm is the fiber under test. The fiber is placed inside an airtight chamber, in which water is then added. The pressure is swept at 1 Hz by injecting air into the chamber. The fiber mainly experiences pressure variations, with negligible thermal fluctuations due to water thermal capacitance. The fiber pressure sensitivity is extracted using Bessel decomposition of the interferometer output signal. We characterized standard G.652 single mode fiber fibers with different tubing, and highlighted its impact on the overall sensitivity. We also tested the setup for a fiber embedded into a Plexiglas plate, here again showing the coupling with the structure and the sensitivity dependence to embedding depth.