Microstrain Sensing with Slow Light in Fiber Bragg Grating

Fiber Bragg Grating (FBG) is widely used in the sensing field for its low insertion loss, small size, low cost and insensitivity to polarization. However, traditional FBGs are limited to the resolution in strain sensing. In uniform FBG, the group time delay of the sidelobe near the bandgap is the largest, and the sensitivity is the highest. This paper analyzes the slow light mechanism produced by light transmitted back and forth in FBG theoretically, explores the influences of different parameters of FBG on the characteristics of slow light by numerical simulation, and realizes the detection of microstrain using the method of power demodulation. The minimum detectable strain is 0.0145 mu epsilon, and the detection accuracy is three orders of magnitude higher than that of traditional wavelength demodulation method.