Simulation and Modeling Optical transmission in Dispersion Managed Scenarios

In recent years, optical fibers became increasingly important means for huge amount of data transport. As time goes on, data dimensions requested become higher and higher, and deployment of submarine links based on optical fibers cables has spread out in all the world. Most recent systems use coherent technology in order to satisfy such data requests due to the fact that coherent transceiver exploits power, phase and polarization modulation. But there exist submarine cables deployed in the past that used to work with older, IMDD (Intensity-Modulation Direct-Detection) technology, in which only power modulation was used to carry information. The peculiarity of these links is that chromatic dispersion is compensated periodically along the fiber spans (Dispersion Managed, DM), by placing Dispersion Compensation Units (DCU). These dispersion compensation maps were engineered ad-hoc to tradeoff between inter-symbol interference compensation and mitigation of non-linearities. Instead, coherent transmission does not need inline chromatic dispersion compensation periodically but dispersion is accumulated and compensated through DSP at the receiver (Uncompensated Transmission, UT) as their nonlinearity is severely impaired by small inline redisual dispersion due to the coherent accumulation between the noise contribution introduced by each fiber span. However, today companies want to still exploit such submarine DM cables leaved from IMDD legacy, since substitution of them in favor of coherent-suited transceiver would be very impactful from an economic point of view. In order to satisfy today's data request, coherent transmission has to be used in such cables. The aim of this thesis is so to understand how to exploit these subsea DM links using coherent transmission technology, extending existing analytical results for UT to DM architectures using a simulative approach in order to extract meaningful informations and validate analytical models. The final scope is so to end up with a quick, handly QoT (Quality of Transmission) estimation that does not require time-consuming numerical simulations to be obtained.