Double Cantilever Beams Accelerometer Using Short Fiber Bragg Grating for Eliminating Chirp

An accelerometer based on the shorter fiber Bragg grating (FBG) is demonstrated and experimentally researched. The reflective optic spectra of FBG under inhomogeneous strain are researched by using the coupled-mode theory; the theoretical analysis demonstrates that the features of the reflective optic spectra are closely related with the chirping coefficient and the length of FBG under inhomogeneous strain. On these basics, an FBG accelerometer based on the double cantilever beams with small strain gradient is pointedly proposed. Experimental results show that the accelerometer has good response characteristic, and it provides broad flat frequency range from 4 to 30 Hz, corresponding sensitivity range from 7.76 to 10.8 pm/ms(-2), while the flatness is less than 3 dB, the cross-axis sensitivity is less than 3.89% of the main-axis sensitivity, and the temperature sensitivity can be effectively eliminated by the self-symmetrical structure.