Recent Advancement of Phase Shifted Fiber Bragg Grating Sensor for Ultrasonic Wave Application: A Review

Fiber Bragg grating (FBG) is gaining traction in the field of optical fiber sensors, either as a detection tool for ultrasonic waves or as a detection target. The significant contributions of the last few years are summarized in this overview, that includes setups based on wavelength and intensity. This article summarizes recent research and development activities in ultrasonic wave applications utilizing FBG sensors and makes recommendations for future research. Several different FBG strain sensor packing configurations are discussed. This article presents a comprehensive theoretical and mathematical analysis of a phase-shifted fiber Bragg grating ( $\pi $ -PS-FBG) for use in a structural health monitoring system that employs a longitudinal ultrasonic strain wave obtained via a natural single FBG. The effect of grating regulating factors (grating length, index change, and apodization), as well as ultrasonic acoustic wavelengths, on the $\pi $ -PS-FBG’s wavelength shift sensitivity have been investigated. Additionally, the slow-light effect in the $\pi $ -PS-FBG acoustic sensor was investigated. Sensitivity, detection range, and limit of detection are all thoroughly examined and discussed with the objective of comparing various technologies and determining future directions in the field of phase shifted fiber optic sensors.