High-frequency optical fiber microphone for condition-based maintenance application

A low-cost optical fiber Bragg grating-based microphone is presented. The sensing system makes use of an intensitybased interrogation approach, with a fixed-wavelength laser source employed as optical source. The optical sensor is complemented by signal processing, consisting of adaptive filters and a Capon power spectral density estimator. System characterization has been carried out, showing maximum sensitivity in the 120-450 Hz range, with 0.45 Hz repeatability on single-tone detection. Application for condition-based maintenance of industrial plants, based on a simulated model, is discussed