Investigation of FEC improvement in a dispersion limited direct modulated 2.5 Gb/s transmission experiment

The use of forward error correction (FEC) coding to reduce power penalties caused by dispersion induced intersymbol interference in direct modulated optical systems is experimentally investigated in this work. For a fiber span length of up to 300 km, the system performance was observed for coded and uncoded direct modulation of a semiconductor laser. The FEC technique improved the system performance, as a result of the correction of the dispersion induced bit errors, in such a way that it made possible for a 2.5 Gb/s direct modulated transmission experiment to reach a former nonviable 300 km fiber span with a "better than back-to-back" performance, at 10/sup -10/ BER.