Experimental evaluation of impairments in unrepeatered DP-16QAM link with distributed raman amplification

Xiaodan Pang, Oskars Ozolins, Atalla El-Taher*, Richard Schatz, Gunnar Jacobsen, Sergey Sergeyev, Sergei Popov

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


The transmission impairments of a Raman amplified link using dual-polarization 16-quadrature amplitude modulation (DP-16QAM) are experimentally characterized. The impact of amplitude and phase noise on the signal due to relative intensity noise (RIN) transfer from the pump are compared for two pumping configurations: first-order backward pumping and bi-directional pumping. Experimental results indicate that with increased Raman backward pump power, though the optical signal-to-noise ratio (OSNR) is increased, so is the pump-induced amplitude and phase noise. The transmission performance is firstly improved by the enhanced OSNR at a low pump power until an optimum point is reached, and then the impairments due to pump-induced noise start to dominate. However, the introduction of a low pump power in the forward direction can further improve the system's performance.

Original languageEnglish
Number of pages8
JournalNature Photonics
Issue number1
Publication statusPublished - 8 Mar 2017

Bibliographical note

© 2017 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (http://creativecommons.org/licenses/by/4.0/).

Funding: EU projects ICONE, gr. # 608099, GRIFFON, gr. # 324391 and Vetenskapsrädet PHASE, gr. #2016-04510.


  • Coherent communications
  • Fiber optics communications
  • Raman amplification


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