Adaptive two-wave mixing interferometry for ultrasonic detection

Abstract

Ultrasound has strong penetrability in opaque media, which makes it one of the most important detection tools for structural safety monitoring. Compared with the traditional piezoelectric transducers(PZTs) used for ultrasonic detection, fiber-optic ultrasonic sensing system based on optical adaptivity of two-wave mixing (TWM) photorefractive crystal has strong characteristics of anti-electromagnetic interference, high sensitivity and strong multiplexing, as well as the adaptive detection for optical phase modulation and permanent dynamic recording of the interference pattern current position, which has a large quantity of applications in structural health monitoring. For the interferometric properties and ultrasonic detection technology of TWM in the field of structural safety monitoring, this paper introduces the principle of adaptive two-wave mixing interferometry, the sensing devices, and methods in various fiber Bragg grating (FBG) sensor systems and dynamic signal detection of Er-doped fiber gratings and discusses the application of fiber-optic ultrasonic sensing systems in ultrasonic detection based on adaptive TWM technology. Finally, the problems and solutions in the sensing system are analyzed. By miniaturizing the TWM interferometer and integrating the entire sensing system, it is expected to further improve the detection performance of the device and expand future research directions.