Hybrid Optimization Method for the Reconstruction of Apodized Chirped Fiber Bragg Gratings

We have studied the hybrid method for reconstructing apodized chirped fiber Bragg gratings, using both an analytic estimation of grating parameters and an optimization algorithm. The Hilbert transform of the reflection spectrum was utilized to estimate grating parameters, and then the layer-peeling algorithm was used to obtain refined parameter values by the differential-evolution optimization process. Calculations for a fiber Bragg grating with wavelength chirp rate 2 nm/cm were obtained with an accuracy of 6 × 10 -5 nm/cm for the chirp rate and 3 × 10 -9 for the index modulation, with much improved calculation speed and high reliability.