Experimental Characterization of Macrobending Fiber Sensor Coupled via Vibrating Membrane for Acoustic Detection

Resumo

This work investigates the application of a fiber-optic acoustic sensor based on macrobending loss for gas leakage detection, employing a membrane-coupled architecture to enhance acoustic sensitivity and directional selectivity. The proposed system integrates a single-mode fiber coiled inside a cylindrical structure sealed with thin membranes, which act as mechanical transducers by converting acoustic waves into localized perturbations along the fiber curvature. The experiments were conducted to evaluate the sensor’s response under controlled excitation conditions, varying frequency, sound pressure level, source distance, and angular orientation. Results demonstrate that tighter curvature yields significantly higher optical attenuation. Spatial sensitivity was characterized by a nonlinear increase in attenuation with distance, and directional behavior was confirmed by enhanced attenuation under oblique wave incidence. The practical applications of the findings are diverse, with particular emphasis on gas leak monitoring in industrial settings.