Benefits of counterpropagating Raman amplification for multiband optical networks
Pedro, J. M.
Pires, J. J. O.
Journal of Optical Communications and Networking Vol. 14, Nº 7, pp. 562 - 571, July, 2022.
ISSN (print): 1943-0620
Scimago Journal Ranking: 1,29 (in 2022)
Digital Object Identifier: 10.1364/JOCN.456582
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Multiband (MB) optical ﬁber transmission systems can unlock additional capacity in existing optical ﬁber infrastructures, enabling them to keep up with the increase in trafﬁc demand while postponing costly optical ﬁber deployments. However, due to the worse transmission characteristics of MB systems than C-band-only
transmission, the network’s overall spectral efﬁciency decreases when increasing the transmission bandwidth. The extent of this performance degradation is paramount to determining the commercial viability of deploying MB systems. By estimating the generalized signal-to-noise ratio using the GNPy library, this work analyzes the impact of using counterpropagating Raman ampliﬁcation to improve the performance of an S +C +L-band transmission system comprising a total bandwidth of 15.5 THz. Raman ampliﬁcation is proposed to mitigate the worse system performance resulting from the stimulated Raman scattering effect and the worse noise ﬁgure of the S-band optical ampliﬁer. We show that the optimized deployment of a counterpropagating Raman pump makes it possible not only to improve but also to equalize the network-wide optical performance of the S +C +L-band transmission system, which potentially reduces the complexity of routing and wavelength assignment algorithms. The capacity, spectral efﬁciency, and number of feasible lightpaths of the S +C +L-band system are compared with C- and C +L-band systems with and without Raman ampliﬁcation on two reference networks. Results show that the spectral efﬁciency of the S +C +L-band system with Raman ampliﬁcation is similar to the C-band-only system without Raman ampliﬁcation. These results provide evidence that this strategy can be effectively used to compensate for the worse transmission characteristics of MB systems, the higher noise ﬁgure of the S-band optical ampliﬁer, the SRS effect, and the additional losses from the band demultiplexer and coupler required at every ampliﬁcation stage to separate the transmission bands. Overall, the simulation results highlight that a single optical ﬁber can approximately carry the same data when using a 15.5 THz transmission band (and Raman ampliﬁcation) as three parallel ﬁbers using C-band-only transmission (without Raman ampliﬁcation).