Theoretical Analysis of Optical Fiber EFPI Sensor Performance for Detecting Lamb Waves

Structural health monitoring technologies using Lamb waves for composite and metallic structures have been studied extensively in order to assess the safety and the durability of the structures. As a good alternative for conventional piezoelectric transducers (PZT), fiber optic sensors are being widely exploited for their sensing applications, including Lamb wave detection. In this paper, a theoretical analysis of optical fiber extrinsic Fabry-Perot interferometer (EFPI) sensor performance is presented to establish a relationship between the variable parameters of an EFPI sensor and its output characteristics due to ultrasonic Lamb wave field. Numerical results reveal that the performance of EFPI sensor is mainly related to the directional angle of the sensor and appropriate gage length for detecting Lamb waves. The obtained conclusions are useful for the measurement of Lamb waves more precisely.