Electronic distortion equalisation by using decision-feedback/feed-forward equaliser for transient and adiabatic chirped directly modulated lasers at 2.5 and 10 Gb/s

A thorough study on the beneficial use of electronic distortion equalisation (EDE) in the transmission performance enhancement of conventional low-cost directly modulated lasers (DMLs) is provided. The studies focus first on the compensation of the chromatic dispersion effect and then on the compensation of cascaded filtering effects of DML generated transmission signals in a system, by means of the feed-forward and decision-feedback equalisers (FFE/DFE). The reported studies consider DMLs with different chirp characteristics operating at 2.5 and 10 Gb/s, using parameters that have been extracted from real lasers, previously verified by simulations and experiments. The performance efficiency of EDE is evaluated in terms of eye-opening penalty degradation associated with the signal transmission over a standard single mode fibre. Extensive simulations reveal significant performance improvement for all the examined cases by using the FFE/DFE. Furthermore, the results show that the equalisation efficiency strongly depends on the chirp characteristics of DMLs.