Modulation Formats for Upgrading MANs to 40 Gb/s per Channel

The explosive growth of traffic demand in current 10 Gb/s optical metropolitan area networks (MANs) requires the rapid upgrade of the bit rate per channel. However, constraints of deployed 10 Gb/s MANs, such as narrowband optical filtering and residual dispersion, impair significantly the performance of most 40 Gb/s modulation formats. To overcome such limitations, several modulation formats have been proposed to upgrade MANs to 40 Gb/s per channel. In this paper, we compare the performance of such formats in upgrading scenarios of 10 to 40 Gb/s MANs considering different optical impairments, namely single- and multi-channel nonlinear fibre effects.