Power budget improvement for long-haul WDM transmission with optimum placement of SOAs

We observed that the optimized optical filter bandwidth for the 100 GHz channel spacing is 0.4 nm. We observe that as we decrease the channel spacing, the quality of signal is degraded. We show that the optimum span scheme-1 is used up to a transmission distance of 68,908 km with good quality for power margin more than 24 dB. This placement scheme of SOAs shows good power budget for long transmission distance. We show the optical spectrum and clear eye diagram at the transmission distance of 68,908 km for optimum span schemes. Finally, we investigate the maximum transmission distance with decrease in channel spacing, i.e., 20 and 50 GHz.