Amplification Schemes and Multi-Channel DBP for Unrepeatered Transmission

• Published in: Journal of lightwave technology Vol. 34; no. 9; pp. 2221 - 2227
• Main Authors: Galdino, Lidia, Mingming Tan, Alvarado, Alex, Lavery, Domanic, Rosa, Pawel, Maher, Robert, Ania-Castanon, Juan Diego, Harper, Paul, Makovejs, Sergejs, Thomsen, Benn C., Bayvel, Polina
• Format: Journal Article
• Language: English
• Published: New York IEEE 01-05-2016; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Achievable information rates; Amplification; Bandwidth; Coherence; coherent detection; Complexity; Computation; Digital signal processing; Erbium-doped fiber amplifiers; Error correcting codes; Fibre; forward error correction (FEC); Gain; Nonlinearity; Optical attenuators; Optical fibers; optical fibre communication; Parity check codes; Raman amplification; Stimulated emission; unrepeatered transmission; coherent detection; Raman amplification; forward error correction (FEC); Achievable information rates; optical fibre communication; unrepeatered transmission
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2016.2521002

The performance of unrepeatered transmission of a seven Nyquist-spaced 10 GBd PDM-16QAM superchannel using full signal band coherent detection and multi-channel digital back propagation (MC-DBP) to mitigate nonlinear effects is analysed. For the first time in unrepeatered transmission, the performance of two amplification systems is investigated and directly compared in terms of achievable information rates (AIRs): 1) erbium-doped fibre amplifier (EDFA) and 2) second-order bidirectional Raman pumped amplification. The experiment is performed over different span lengths, demonstrating that, for an AIR of 6.8 bit/s/Hz, the Raman system enables an increase of 93 km (36 %) in span length. Further, at these distances, MC-DBP gives an improvement in AIR of 1 bit/s/Hz (to 7.8 bit/s/Hz) for both amplification schemes. The theoretical AIR gains for Raman and MC-DBP are shown to be preserved when considering low-density parity-check codes. Additionally, MC-DBP algorithms for both amplification schemes are compared in terms of performance and computational complexity. It is shown that to achieve the maximum MC-DBP gain, the Raman system requires approximately four times the computational complexity due to the distributed impact of fibre nonlinearity.