An Infrasound Sensor Based on Extrinsic Fiber-Optic Fabry–Perot Interferometer Structure

An infrasound sensor based on an extrinsic fiber-optic Fabry-Pérot interferometer structure is reported and demonstrated. The transducer part of this sensor is a composite film which is composed of a 3-μm-thick small round aluminum foil and a ~50-μm-thick polymer polyethylene terephthalate film. The infrasound interference will introduce the vibration of the film and result in the changes of the FP cavity length synchronously, as well as the interference spectral shift. As a consequence, we will obtain the synchronous changes of reflected power by inputting a single wavelength laser. Theoretical simulation and experimental validation are both carried out to test the performance of our fiber infrasound sensor. Results show that low-frequency infrasound signal from 1 to 20 Hz can be detected with low distortion. The proposed sensor has its superiorities and can be useful for low-frequency infrasound sensing.