Roll-off Factor Influence of Nyquist Pulse in PDM- OFDM optical fiber system

Spectral efficiency (SE) serves as a pivotal metric in the optimization of long-haul optical fiber transmission systems. According to the second Nyquist criterion, the Nyquist pulse represents the pulse requirement that the system must fulfill to avoid Inter-Symbol Interference (ISI). Nevertheless, a delicate balance exists between spectral bandwidth and the feasibility of the modulation format. This paper delves into the analysis of SE for Nyquist pulses within a 1.2 Tb/s PDM-OFDM superchannel system. Our findings reveal multiple optimal roll-off factor α, contingent upon varying factors such as OSNR, SER, and EVM.