Design methods of long-period fiber gratings for the equalization of nonflat erbium gain spectrum

We show how to design long period fiber gratings (of two structures) modeled as the multi-port lattice using the simulated annealing and steepest descent methods for the equalization of the erbium-doped fiber amplifiers (EDFA). We have obtained design parameters of piecewise-uniform long period fiber gratings which fit the inverted erbium gain spectrum of a commercially available EDFA over the entire 1525 nm - 1570 nm range. We analyzed the sensitivity of designed structures by Monte-Carlo simulations.