40 Gbit/s × 25 WDM 306 km unrepeatered transmission using 175 μm²-Aeff fibre

A 40 Gbit/s-based unrepeatered terabit wavelength division multiplexing (WDM) transmission was demonstrated by using Aeff fibre allocated at each end of the transmission line without using a separate fibre for pump power transmission. The light for odd channels was combined with an arrayed-waveguide grating (AWG) followed by an intensity modulator and a pulse generator. The return to zero (RZ) signals produced by the modulator were divided into two identical data-streams, and were optically multiplexed to generate 40 Gbit/s RZ signal. The signal obtained had optical delay avoiding correlation between the data streams. The odd and even channels were then combined with a polarising beam splitter (PBS) in orthogonal state of polarization.