Optimal Design of High-Channel-Count Fiber Bragg Grating Filters With Low Index Modulation Using an Improved Differential Evolution Algorithm

An effective optimization method based on a self-adaptive differential evolution (DE) algorithm is proposed to design high-channel-count fiber Bragg grating (FBG) filters. By combining the optimization algorithm with the tailored group delay technology, we have established a mathematical model aiming at minimizing the maximum index modulation of the grating. Equipped with a parameter self-adaptive strategy, the improved DE algorithm shows its powerful global searching ability in finding the optimal group delay parameter for each channel. Design examples demonstrate that the proposed approach yields better results with a remarkable reduction in the maximum index modulation compared with the previous works. Furthermore, we numerically present a 1037-channel 50-GHz spaced FBG filter enabling to cover the whole bands (O + E + S + C + L + U), which indicates the potential application of this method in the dense wavelength-division multiplexing (DWDM) system.