Influence of laser chirp on the performance of 40 Gbit/s optically compensated directly modulated systems

The influence of laser chirp on the performance of 40 Gbit/s directly-modulated (DM) long-haul systems (LHS) using optimised optically pre-compensated dispersion maps (OPDM) are assessed through numerical simulation. It is shown that, for a laser chirp parameter of 3.5, the interplay of high laser chirp with linear and nonlinear fiber effects leads to signal distortion that prevents the efficient use of 40 Gbit/s/ DM-LHS. However, a reduced laser chirp parameter of 1.5 allows a strong improvement of signal transmission, foreseeing the possibility of using DM-LHS with OPDM. In addition, it is also shown that the right balancing between the laser´s transient and adiabatic chirps plays a decisive role in order to attain the best performance of DM-LHS using OPDM.