Optical Fiber Sensors Based on Core-Offset Structure: A Review
Huiwen Niu, Shuo Zhang, Wenhuan Chen, Yue Liu, Xiang Li, Yunxiang Yan, Shengjia Wang, Tao Geng, Weimin Sun, Libo Yuan
Abstract
This review focuses on the preparation methods and wide applications of optic fiber sensors based on core-offset structure. Firstly, the classification and preparation methods of core-offset structures are introduced. Then, the applications of different types of sensors based on the core-offset structure are investigated, including the measurement of physical parameters such as temperature, strain, refractive index (RI), bending, magnetic field by Mach-Zehnder interferometer (MZI), cascaded sensor, long period fiber grating (LPFG), fiber Bragg grating (FBG), Fabry-Perot interferometer (FPI) and Surface plasmon resonance (SPR). Compared with the traditional fiber sensor, core-offset structure sensor with a non-axisymmetric characteristic has excellent sensing characteristics, especially in the recognition of bending direction and high RI sensitivity. Furthermore, the design scheme, working principle and sensing characteristics of different core-offset sensors are also briefly described. Finally, the existing challenges and development direction of optic fiber sensors based on core-offset structure is discussed and prospected.