Metal-coated high-temperature strain optical fiber sensor based on cascaded air-bubble FPI-FBG structure
Jianqiao Liang, Yang Yu, Qiang Bian, Wenjie Xu, Zhencheng Wang, Shumao Zhang, Junjie Weng, Jiajian Zhu, Yong Chen, Xiaoyang Hu, Junbo Yang, Zhenrong Zhang
Abstract
Metal coatings can protect the fragile optical fiber sensors and extend their life in harsh environments. However, simultaneous high-temperature strain sensing in a metal-coated optical fiber remains relatively unexplored. In this study, a nickel-coated fiber Bragg grating (FBG) cascaded with an air bubble cavity Fabry-Perot interferometer (FPI) fiber optic sensor was developed for simultaneous high temperature and strain sensing. The sensor was successfully tested at 545 °C for 0-1000 µɛ, and the characteristic matrix was used to decouple temperature and strain. The metal layer allows easy attachment to metal surfaces that operate at high temperatures, enabling sensor-object integration. As a result, the metal-coated cascaded optical fiber sensor has the potential to be used in real-world structural health monitoring.