Advances of some critical technologies in discrete and distributed optical fiber sensing research
Authors: Liu Tie-Gen  , Yu Zhe  , Jiang Jun-Feng  , Liu Kun  , Zhang Xue-Zhi  , Ding Zhen-Yang  , Wang Shuang  , Hu Hao-Feng  , Han Qun  , Zhang Hong-Xia  , Li Zhi-Hong  ,   School of Precision Instrument and Opto-Electronics Engineering, State Key Laboratory of Hydraulic Engineering Simulation and Safety, Key Laboratory of Opto-electronics Information Technology Ministry of Education, Tianjin Optical Fiber Sensing Engineering Center, Tianjin University, Tianjin 300072, China
Published: December 2020

With the superiority of anti-electromagnetic interference, corrosion resistance, light quality, small size and so on, optical fiber sensing technology is widely used in aerospace industry, petrochemical engineering, power electronics, civil engineering and biological medicine. It can be divided as discrete and distributed. Discrete optical fiber sensing utilizes fiber sensitive element as sensors to detect the quantity to be measured. Optical spectrum, light intensity and polarization are usually used as the sensitivity parameter because they can be modulated by parameter such as rotation, acceleration, electromagnetic field, temperature, pressure, stress, stress, vibration, humidity, viscosity, refractive index and so on. Fiber works as the channel and links the fiber sensor and demodulating equipment. After a long period of research, the discrete optical fiber sensing technology stretch out many branches, we discussed the most representative ones as follows, the fiber grating sensing technique, the fiber fabry perot sensing technique, the fiber gyroscope sensing technique, the fiber intracavity sensing technique, the fiber surface plasma sensing technique, hollow-core fiber whispering gallery mode sensing technique, magnetic fluid fiber sensing technique and fiber-based optical coherence tomography sensing technique. Based on optical effect as rayleigh scattering, Raman scattering and Brillouin scattering, distributed fiber sensing system uses fiber itself as a sensor, when the vibration, stress, voice or temperature acts on the fiber changes, the optical signal transfers inside the fiber will change accordingly. The fiber distributes in a large range and a long distance, then the signal can be located at different positions and realize the multi-position measurement. We discussed the main distributed fiber sensing technologies as follows, the interferometric disturbance fiber sensing technology, the optical frequency domain reflectometry fiber sensing technology, the -optical time domain reflectometer fiber sensing technology, the optical fiber Brillouin sensing technology and the optical fiber Raman sensing technology. The development of technology is promoting the integration and network of optical fiber sensing, now it also becomes a research hotspot. Fiber optic smart sensor network is formed by various discrete and discrete optical fiber sensors in certain topological structure with the function of self-diagnosis and self-healing. Current research concentrates in the following areas, the increase of the multiplex sensor number, the topological structure with higher robustness and the intelligent control of sensing network. In this paper, we discuss the origination, development and research progress of discrete, distributed optical fiber sensing technologies and optical fiber sensing network technology, and the future research direction is also prospected.