Fiber-ring Laser Sensor System Using a Fiber Fabry-Pérot Filter for Ultrasound Detection

We propose and experimentally demonstrate a multiplexing methodology for ultrasonic sensors based on fiber Bragg gratings (FBGs) that are included in the laser cavity of a semiconductor optical amplifier (SOA)-based fiber-ring laser system coupled with a fiber Fabry-Perot (FFP) filter. The fiber ring laser (FRL) consists of an SOA as a gain medium and of FBGs as wavelength selection elements. We experimentally fabricate a dual-wavelength fiber ring laser and confirm stable oscillation outputs of the laser source. And ultrasonic signals generated from the piezoelectric transducers (PZTs) source are successfully detected. Such a multiplexed fiber-optic ultrasonic sensor system may be used for acoustic emission (AE) detection for structural health monitoring (SHM).