Dear Hafiz,
The lesson talks about how it is possible to design an optimal gain flattening filter in OptiSystem for optical amplifier. Users will enter the required final gain flatness (let us say 1dB gain flattening) across the required operating wavelength range. The software looks into the gain curve obtained at specific signal input power and design the gain flattening filter for that set gain flattening value. There is no genetic algorithm used in the GFF design feature.
regards,
Ahmad