Interferometric Optical Fiber Sensor for Acoustic Emission Detection: Experimental Evaluation and Configuration Optimization

This study presents the experimental optimization of an interferometric optical fiber sensor for acoustic emission (AE) detection. The system employs a simple and low-cost structure composed of sensing and reference fibers, enabling interference-based detection without specialized components such as fiber Bragg gratings or Fabry–Perot cavities. A narrowband laser source was selected through comparative experiments for its superior stability and interference performance. The influence of fiber-loop parameters, including the number of turns and the optical-path intensity ratio, was systematically evaluated to clarify their effects on AE sensitivity and frequency response. The experimental results demonstrate that detection performance and bandwidth can be flexibly tuned by optimizing the loop configuration. Finally, the sensor was validated using a tensile test, successfully detecting AE signals in the range of 20 kHz to 1 MHz. The proposed system provides a robust, EMI-resistant, and cost-effective interferometric solution for AE monitoring.