Technical and commercial perspective of 40 Gbs transmission

The availability and the function of 40 Gb/s technology is described. With this technology, transition from 10 Gb/s to 40 Gb/s, contrary to the previous transition from 2.5 Gb/s to 10 Gb/s, is evolutional and, therefore, much less painful for the carriers. Specifically, during this evolutional transition, already installed 10 Gb/s WDM systems can be in-service upgraded to 40 Gb/s by adding 40 Gb/s line cards (transmitters an receivers) instead of 10 Gb/s line cards. Also, the new systems are currently designed to be hybrid, where 10 Gb/s and 40 Gb/s waves can co-exist in one spectral band, but not necessarily have the same channel spacing. Dispersion compensation of the system is also considered using dispersion compensating fiber placed at each in-line amplifier. The robustness of the system was also discussed.