The Principle and Application of Optical Fiber Sensing Technology: Three Kinds of Distributed Sensing and Fiber Bragg Grating

Abstract In modern society, optical fiber plays a significant role in ordinary people’s life. The development of optical fiber communication is so fast while the optical fiber sensing has gained huge achievements although fewer people know about that. In fact, optical fiber sensing technology has become increasingly popular due to its low price and the fact that this method overcomes the problems encountered with traditional sensor, such as in the high-intensity magnetic field. Meanwhile distributed sensing enables the all-day and all-spots monitoring. Based on different principles, distributed optical fiber sensing could be classified into three kinds, which are optical time-domain reflectometry based on Rayleigh scattering, Raman-optical time-domain reflectometry based on Raman Scattering and Brillouin-optical time-domain reflectometry based on Brillouin scattering. These three methods have their own benefits and applications because of their special structures. Fiber Bragg grating can be taken as one kind of optical fiber sensor as well as the grating locates inside the optical fiber. Relying on the diffraction effect, FBG can measure temperature, strain and even pressure sensitivity. The demodulation methods of FBG are various as well. There are about 8 different methods that can meet different requirements, each with its own benefits and defects.