Multipoint Overlapping Optical Networks

Coherent transmission has drastically evolved in the last decade to provide high flexibility to improve spectral efficiency. This yields a point-to-point capacity close to Shannon's limit. In this work, we present the multipoint overlapping optical network architecture in a multi-transmitter to single-receiver context to boost the network capacity. It overlaps two optical signals, partly reusing network resources, here frequency slots of 12.5 GHz width. We show that a joint digital signal processing, based on multi-stage parallel interference cancellation efficiently compensates inter-channel interference up to 39% spectrum overlap with a 1 dB SNR penalty for PDM-QPSK signals. To investigate the impact of the residual interference penalty, we model the proposed solution as an additional power-independent Gaussian-noise term introduced in the transmission. Experiments and simulations have successfully validated the model and the extra penalty is shown to be dependent only on the chosen overlapping given factor. Finally, with such a model, we study the network gains brought by the proposed architecture. We investigate different networking scenarios assuming either 2-slot and 3-slot of overlapping, resulting in similar to 20% and similar to 40% of overlapping. We demonstrate a network capacity gain of up to 17%.