Fiber bragg grating vibration sensor

The utility model discloses a fiber bragg grating vibration sensor used for monitoring dangerous rocks along the railway. The sensor comprises a support housing, an L-shaped dwang, a strain fiber bragg grating, and an overload protection device. The L-shaped dwang is provided with two arms which are vertical to each other and intersects on a length direction. The L-shaped dwang is also provided with a rotary shaft. The rotary shaft is vertical to the two arms and is fixed with the support housing, so that the L-shaped dwang can rotate relative to the rotary shaft. A first end of the strain fiber bragg grating is packaged on a first arm of the L-shaped dwang, and a second end of the strain fiber bragg grating is packaged on the support housing. The second arm of the L-shaped dwang is support by a spring so as to remain horizontal. The overload protection device limits a range of motion of a free end of the second arm, so as to limit a rotation range of the L-shaped dwang.