High accuracy FBG temperature sensor based on quadratic polynomial fitting

In order to improve the accuracy of the FBG temperature sensor, a new packaging method is proposed and the detected temperatures are fitted by quadratic polynomial function. The new packaging method can eliminate the cross-sensitivity of stress. Linear fitting and quadratic polynomial fitting are applied respectively, and the sensor demonstrates good stability and repeatability by quadratic polynomial fitting. The degree of the quadratic polynomial fitting is greater than 0.9999 and the temperature error is less than 0.13℃ in the temperature range of 0℃~80℃. The proposed sensor can be applied in engineering practice with good accuracy and reliability.