Unrepeatered 240-km 64-QAM transmission using distributed raman amplification over SMF fiber

P. Rosa*, G. Rizzelli, X. Pang, O. Ozolins, A. Udalcovs, M. Tan, M. Jaworski, M. Marciniak, S. Sergeyev, R. Schatz, G. Jacobsen, S. Popov, J. D. Ania-Castañón

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We present a theoretical and experimental investigation of unrepeatered transmission over standard single-mode fiber (SMF-28) using several schemes of distributed Raman amplification, including first, second, and dual order. In order to further extend the transmission distance, we utilize advanced bidirectional higher-order ultra-long Raman fiber laser-based amplification, where we use fiber Bragg gratings (FBGs) to reflect Stokes-shifted light from the secondary pumps. Our work demonstrates the possibility of transmission up to 240-km span length with a total span loss of 52.7 dB. Here, we use a 28-Gbaud signal using a 64-quadrature amplitude modulation (QAM) modulation format. Our results highlight the contribution of nonlinear compensation using digital back propagation in a digital signal processor (DSP) code at the receiver.

Original languageEnglish
Article number1433
JournalApplied Sciences (Switzerland)
Issue number4
Publication statusPublished - 20 Feb 2020

Bibliographical note

This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited


  • Digital backpropagation
  • Distributed raman amplification
  • Unrepeatered 64-QAM transmission


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