Characterization of Chirped Fiber Bragg Gratings: Identification and Removal of Cladding-Mode Perturbations in Measurement Data

In chirped fiber Bragg gratings, structural perturbations and the effect of cladding-mode coupling are shown to be distinguishable. To this end, the absolute value and the phase of the experimentally determined complex coupling coefficient are Fourier transformed separately, yielding a set of discrete lines that can be clearly identified and be traced back to cladding-modes. Removing these lines yields the grating properties in the absence of cladding-modes.