A novel fiber Bragg grating vibration sensor system was presented based on the demodulation by a mechanical-induced long period fiber grating(MLPFG).The stainless steel grooved board which was fabricated by mechanical line processing technology (MLPT),was used to make MLPFG with period of 600 μm,length of 60 mm.The MLPFG was adopted as filter in system,and its center wavelength is 1 539.820 nm,the length of the slope is larger than 6 nm.The vibration sensor was made by a special chosen FBG,whose...