Application of a photonic crystal fiber LPG for vibration monitoring

A fiber optic sensor based on a long-period grating (LPG) inscribed in a photonic crystal fiber is investigated for vibration sensing for structural monitoring applications. In this paper, preliminary results are shown demonstrating the sensor ability to detect vibration induced in a test structure. The sensor frequency response when attached to a loudspeaker-acrylic plate stimulation system (tested in the range from 40 Hz to 2.5 kHz) is analyzed using an intensity based scheme with a tunable laser. An alternative interrogation scheme, where the vibration signal is retrieved from a spectral scan, is also demonstrated and analyzed showing promising characteristics for structural health monitoring.