Comparative analysis of single span high speed 40 Gbps long haul optical link using different modulation formats in the presence of Kerr nonlinearity

Rapid increase of the data traffic in communication world has accelerated the development of high capacity long-haul optical links, and the main barrier across these links are the chromatic dispersion and various nonlinear effects. This paper examines the long distance optical link up to 4000 km in the presence of Kerr nonlinearity using various modulation formats using three dispersion compensation schemes at different transmission distances. Here comparative analysis is carried out for the 40 Gbps long haul optical link using carrier-suppressed return to zero (CSRZ), modified duo binary return to zero (MDRZ) and differential phase shift keying (DPSK) modulation formats. The effect of change in the input power and transmission distance is observed in terms of Q value, BER and eye opening of various formats. It is observed that the performance of the system is greatly deteriorated by the Chromatic Dispersion and DPSK modulation format comes out to be the best choice for the long distance transmission up to 4000 km and beyond. Also the pre, post and symmetrical analysis is also carried out for all three modulation formats and optimum results are achieved with the symmetric configuration.