Non-destructive technique for characterization fiber Bragg gratings via diffraction profile

This research introduces a new non-destructive technique for the characterization of fiber Bragg gratings (FBGs) based on the analysis of the FBG diffraction profile via measuring its asymmetry and intensity. This approach enables the determination of such FBG parameters as an off-axis displacement, aberrations of the focusing system, outcoupling efficiency of refractive index modulation, grating length, and grating order. This proposed technique can significantly improve quality control in FBG manufacturing. The applicability of this technique is demonstrated on different types of fiber Bragg gratings written by point-by-point femtosecond laser writing.