Reconstruction of phase-shifted fiber Bragg grating parameters using genetic algorithm over thermally-modulated reflection intensity spectra

This paper presents a numerical method for the inverse extraction of the multiple physical parameters of phase-shifted fiber Bragg gratings (FBGs). In the proposed approach, the reflection intensity spectra produced by two known temperature distributions are taken as objective functions and a genetic algorithm is then employed to perform an iterative search for the corresponding parameters of the phase-shifted FBG, including the grating period, the grating position, the grating length, the refractive-index modulation depth, the apodize factor, and the phase-shift position. The numerical results confirm that the proposed method successfully synthesizes the parameters of phase-shifted FBGs with various structures with a high degree of accuracy. Furthermore, the method has the advantages of simplicity, low cost and a nondestructive nature. Accordingly, the method is suitable for widespread application in the fiber communications and fiber laser components fields.