Performance improvement of FBG sensors based on the pre-stressed package technique

Packaging technology is a key factor in fiber Bragg grating (FBG) sensing, which can greatly affect the sensing performance of FBG sensors. In this paper, a pre-stressed packaging method for FBG sensors is proposed. The method enables the pre-stress applied on the FBG to be continuously and accurately adjusted when the FBG sensor is packaged, thereby ensuring the stability of the pre-stress. In order to implement the method, an instrument is designed and fabricated as well. The proposed method is demonstrated through some experiments, experimental researches indicate that using the proposed method, the spectrums of the fourteen packaged FBG sensors have no chirping nor broadening the spectral 3 dB bandwidth. The average temperature-dependent sensitivity coefficient of fourteen sensors is 2.03 x 10(-5)/degrees C, the relative error is 1.7%, and the average linearity is better than 0.999. So, the proposed pre-stressed packaging method has advantages of great stability, good repeatability, easy operation and low cost.