Fiber Strain Sensor with Enhanced Sensitivity Utilizing Differential Pair of Fiber Bragg Gratings

A sensitivity enhanced demodulation method for the fiber Bragg grating (FBG) sensing system is presented with a pair of reference FBGs. One of the reference FBGs and the sensing FBG have the same Bragg wavelength, but the other reference FBGs has a Bragg wavelength offset relative to the sensing FBG. Reflected optical signals from the sensing FBG passed through two reference FBGs, and subtracted with each other after detection. Proposed scheme is verified using a rail load platform with doubled strain measurement sensitivity compared to the general matched grating approach.