100 Gbps coherent MB-OFDM for long-haul WDM optical transmission. (Transmission optique longue distance avec le format MB-OFDM cohérent à 100 Gbps)

The demand for more broadband services such as video on demand, social networking, cloud/grid computing...is expected to grow up. To support and provide these services to the users, the capacity in access network must increase, driving thus data rate increase in metro/core transport network. In the past, the demand for more capacity in WDM long-haul transport network has been enabled by increasing the capacity from 2.5 Gbps to 10 Gbps based on the NRZ-OOK modulation, and by overcoming the impact of chromatic dispersion (CD) through the insertion along the transmission line of inline dispersion fiber modules. However, upgrading more the capacity of the OOK channels while keeping the legacy G-652 fiber based infrastructure was not possible due to the detrimental impact of the polarization mode dispersion (PMD) at high data rate. Fortunately, the coherent technology that permits the compensation of CD and PMD in the electronic domain and the use of multi-level modulation has enabled high data-rate transmission. Today the 100 Gbps coherent dual polarization quadrature phase shift keying (DP-QPSK) is standardized as the industrial solution for long-haul WDM transmission. Another alternative format to DP-QPSK that permits also to reach a data rate of 100 Gbps and beyond (400 Gbps & 1Tbps) is the coherent orthogonal frequency division multiplexing (Co-OFDM) format. This last one is intrinsically robust against CD and PMD and permits high spectral efficiency. However a doubt exists whether the OFDM can be as efficient as QPSK for long-haul WDM transmission due to its supposed higher sensitivity to nonlinear effects. In this thesis, we have investigated the potential of Co-DP-OFDM for 100 Gbps WDM transport. The digital signal processing algorithms are detailed and also, the different experimental set-ups required to carry out and validate the 100 Gbps transceiver are shown. We also present the transmission results obtained with several configurations. In one of these configurations, the 100 Gbps Co-DP-OFDM channel is multiplexed with forty 100 Gbps DP-QPSK channels and all these channels are transmitted over 1000 km of DCFfree G.652 fiber, while in another configuration, the Co-DP-OFDM and Co-DP-QPSK channels are combined with 78 NRZ-OOK channels and transmitted over 1000 km of dispersion managed G.652 fiber line. We have demonstrated that OFDM and QPSK have nearly the same performance after a transmission over 1000 km of DCF-free fiber line, and also we have demonstrated that the transmission of these two formats over legacy fiber infrastructure (with the presence of the 10 Gbps NRZ-OOK channels) is possible under the condition of decreasing the 10 Gbps channel power with respect to the 100 Gbps Co-DP-OFDM and Co-DP-QPSK channels by 5 dB. The results presented in this thesis are very valuable when considering the next generation of 400 Gbps or 1 Tbps for WDM systems.