Research on a vibration sensor system with temperature compensation using double-matched FBGs

Abstract

In order to improve the demodulation sensitivity and range of fiber Bragg grating(FBG)vibration demodulation system and eliminate the influence of ambient temperature on demodulation signal,a fiber Bragg grating vibration demodulation system with temperature compensation is developedUsing two transmission mode matching FBGs with center wavelengths symmetrically located at both sides of that of the sensing FBG,two symmetrical and complementary sensing channels are established in the system and then the vibration demodulation is realized based on difference principleThe system performance is simulated by Matlab software and the results show that compared with traditional method,the proposed method can effectively improve the demodulation sensitivity and range of the systemThe matching FBGs are packaged together with a thermoelectric cooler(TEC)and a judging channel of temperature compensation is establishedWhen the output of judging channel exceeds the threshold set previously for temperature regulation judgment,the center wavelengths of matching FBGs are re-matched with the sensing FBG by changing the package temperature of matching FBGs with TEC controller,thereby realizing the temperature compensation of the systemThe experimental results show that the normalized system demodulation sensitivity is 5168/nm,the demodulation range is 12nm,and the normalized threshold voltage of judging channel is 08905The feasibility of system temperature compensation and judgment mechanism is demonstrated by measurement of the same vibration signal under four different environment temperatures using the developed demodulation system