Simultaneous strain and temperature distribution sensing using two fiber Bragg grating pairs and a genetic algorithm

This study uses two pairs of FBGs to perform simultaneous strain and temperature field measurements. The first pair of FBGs, comprising one uniform FBG and one chirped FBG, measures the strain and temperature fields, while the second pair of FBGs, also comprising one uniform FBG and one chirped FBG, measures the temperature field only. A genetic algorithm is applied to reconstruct the arbitrary strain and temperature distribution profiles simultaneously from the measured reflection intensity spectra of the four FBGs. Various examples of nonmonotonic variations in the strain and temperature fields are considered for illustration purposes. It is found that the proposed scheme successfully reconstructs the applied strain and temperature fields.