Record spectral efficiencies and transmission capacities based on N×43 Gbit/s systems

Spectral efficiency in excess of 0.8 bit/s/Hz has become reality with 43 Gbit/s NRZ based DWDM systems. We highlight the basic approaches to reach such efficiencies through the record transmission capacities of 10 Tbit/s over 300km TeraLight™ fibre using an optical bandwidth of 8 THz offered by the C-and L-band, and of 3.2 Tb/s in C band over 900km fibre. The key approaches for the high spectral efficiency are vestigial sideband (VSB) filtering, polarization multiplexing and 43 Gbit/s NRZ modulation format. The key elements for transmission are: TeraLight™ fibre, dispersion management, OSNR control by a well defined combination of erbium-doped and Raman fibre amplification and finally forward-error-correction coding.