112 Gbit/s RF-assisted dual carrier DP-16-QAM transmitter using optical phase modulator

An RF-assisted 112 Gbit/s transmitter based on optical phase modulation is presented. The system uses two closely spaced sub-channels generated using radio frequency (RF) electronics. Numerical simulations as well as experiments over 824 km of installed fiber are used for evaluation. The analysis shows that performance almost as good as for a conventional Mach-Zehnder modulator can be obtained. Although a relatively high OSNR is required due to the large fraction of power residing in the optical carrier, very small penalty is observed for optimum power levels in the transmission link.