DUOBINARY TECHNIQUE FOR DISPERSION REDUCTION IN HIGH-CAPACITY OPTICAL-SYSTEMS - MODELING, EXPERIMENT AND FIELD TRIAL

The paper presents optical duobinary signalling as an alternative to t he binary format for improved transmission performance in dispersion-l imited systems and summarises results achieved from both experimental and theoretical investigations, The potential advantages of duobinary transmission for dispersion accommodation in high capacity systems are demonstrated in both laboratory experiments and installed optical fib res. Unrepeatered transmission at 10 Gbit/s without dispersion compens ation was achieved with penalties of only 1.5 dB after 120 km and 2.5 dB after 138 km. Initial indications of the influence of self-phase mo dulation (SPM) and stimulated Brillouin scattering (SBS) on duobinary transmission are also presented. Two channel, 2 x 100 bit/s wavelength division multiplex (WDM) operation with mixed binary and duobinary tr ansmission was demonstrated in a field trial. This is the demonstratio n of using both binary signallings at a total capacity of 20 Gbit/s ov er installed fibre. The investigations show that duobinary signalling should become an important transmission format for future wideband net works where system performance is primarily dispersion dominated.