A Comparison of DGT and Power Mask for EDFA Modeling in GNPy

EDFAs (erbium-doped fiber amplifiers) are essential equipment in optical networks. In addition to enabling transmission over long distances in the all-optical domain, EDFAs amplify several optical spectrum channels. An intrinsic problem with EDFAs is that the channels are not equally amplified, with variation in gain along the spectrum according to the chosen operating point. This problem can considerably impair the transmitted signal in a cascade of amplifiers. How the amplifier characteristics and operation are represented is critical to predicting the signal quality at the end of the link. This paper compares two strategies for representing optical amplifier operation: DGT (Dynamic Gain Tilt) and Power Mask. We perform simulations using the GNPY library and two commercial EDFA models. The results indicate that the DGT estimation is worse when the amplifier has a high ripple operating point, reaching a 13 dB difference in the output power spectrum at the end of a link with 4 EDFAs.