Mechanical Filter-Based Differential Pressure Fiber-Optic Fabry-Perot Infrasound Sensor

Abstract

A differential pressure fiber optic infrasound sensor based on a mechanical filter was developed, for the detection of infrasound within the frequency range of 0.01-1 Hz. The sensing unit employs a miniature polyphenylene sulfide (PPS) diaphragm which is fixed onto a glass ferrule. An extrinsic Fabry-Perot (F-P) interferometer was fabricated between the optical fiber end face and the PPS diaphragm, and a mechanical filter structure introduced to improve the minimum detectable frequency down to 0.005 Hz. Experimental results indicate that this infrasound sensor shows a favorable frequency response for infrasound signals between 0.01 and 1 Hz, and it exhibits an average minimum detectable pressure (MDP) of 88.85 mPa• Hz -1/2 . Our platform provides a promising solution for sensors in infrasound signal detection applications.

A Fiber-Optic Accelerometer Based on Extrinsic Fabry-Perot Interference for Low Frequency Micro-Vibration Measurement

“…where I is the intensity of the signal reflected by the sensor, I 0 is the intensity of the incident light, R is the reflectivity of interfaces, L is the length of the F-P cavity, and λ is the central wavelength of the DFB laser. When using intensity demodulation, we expect the sensor to work within the π/4 linear range centered on the maximum point of derivative of sinusoidal interference curve [26]. The expected cavity length of the sensor is analyzed according to (5), and the cavity length L should meet the following condition,…”