A novel fiber Bragg grating sensor interrogation system utilizing a tunable Fabry-Perot filter

To improve the performance of FBG interrogation system,a novel fiber Bragg grating sensor interrogation system based on a tunable fiber Fabry-Perot (FFP) filter was demonstrated.Firstly,a reference fiber Bragg grating (FBG) was used as a wavelength reference element.By measuring the wavelength difference between reference FBG and sensor FBG,the drift of tunable FFP filter's cavity length was compensated.Secondly,a quadratic fit function wa s made with software based on experiment results.This function showed a good fit to the relationship between the displacement of PZT and control voltage.It was used to calculate the wavelength of the sensing FBG.In experiment,a strain of 0~1800 με was applied to the sensing FBG and the maximum nonlinearity deviat ion of measured wavelength was 0.5%.Experiment results show that the measured er ror caused by the drift of FFP filter's cavity length and PZT's nonlinearity is greatly reduced and a higher accuracy is obtained.