Terabit transoceanic system assessment with industrial margins using 25 GHz channel spacing and NRZ format

We have transmitted 1.12 Tbit/s over 6300 km using only 22.2 nm of C-band EDFAs with 25 GHz spacing and NRZ modulation format. The average performance obtained correspond to a 3.6 dB margin for a system designed with Enhanced 7% redundancy FEC scheme based on concatenated Reed-Solomon code. This experiment demonstrates for the first time the industrial feasibility of a 1.1 Tbit/s transoceanic transmission which is compatible with 0.4 (bit/s)/Hz. The use of NRZ format has two advantages. The first one is a low cost and compact terminal equipment due to less modulation stages compared to RZ or CRZ. The second one is a better compatibility with high channel density allowing simpler and lower cost repeaters for a given capacity.