Equalization of erbium gain spectrum using the multiport lattice filter

We propose an accurate modeling technique of concatenated long-period fiber gratings. The proposed technique is then applied to the synthesis of long-period fiber gratings for the erbium gain equalization using the simulated annealing and the steepest descent minimization technique. We have obtained design parameters of the piecewise-uniform long-period fiber gratings that rt the inverted erbium gain spectrum of a commercially available erbium-doped fiber amplifier (EDFA) over the entire 1525 nm to 1570 nm range.