Enhancing the Signal Power Symmetry for Optical Phase Conjugation Using Erbium-Doped-Fibre-Assisted Raman Amplification

Mingming Tan*, Thanh Tu Nguyen, Paweł Rosa, Mohammad Al-Khateeb, Tingting Zhang, Andrew D. Ellis

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


We propose a novel dual-order backward-pumped distributed Raman amplification scheme assisted erbium-doped-fibre (EDF) providing nearly perfect signal power symmetry (>93% symmetry level) over two 50.4 km single mode fibre spans. Compared with conventional dual-order Raman schemes, this scheme only requires an additional short (25 cm) erbium-doped fibre to compensate the loss from the passive components between spans, significantly improving the overall link symmetry. Unlike a conventional hybrid Raman/EDFA approach with separate amplifier modules, the proposed scheme offers cost savings by utilizing the Raman pumps to activate the erbium-doped fibre, avoiding the need for an EDF-designated pump. In an optical transmission system with four 50.4 km fibre spans, our novel Raman scheme presented in this paper enables mid-link optical phase conjugation (OPC) to compensate up to 37 dB of nonlinear Kerr inter-signal interference. This represents a 12 dB advantage in compensation over conventional dual-order Raman amplification. Our experimental and simulated results also demonstrate that the proposed configuration provides 7 dB nonlinear threshold enhancement in a 200 Gb/s DP-16QAM 200 km inline transmission system using a mid-link OPC, exceeding the enhancement observed with the conventional dual-order Raman scheme. Our simulation results also show that the optimum Q2 factor using the proposed scheme outperforms the conventional schemes at 2000 km.
Original languageEnglish
Article number9293297
Pages (from-to)222766-222773
Number of pages8
JournalIEEE Access
Publication statusPublished - 14 Dec 2020

Bibliographical note

This work is licensed under a Creative Commons Attribution 4.0 License. For more information, see https://creativecommons.org/licenses/by/4.0/

Funding: EU MSCA, GRANT 748767; Engineering and Physical Sciences Research Council EP/S003436/1


  • Optical amplifiers
  • nonlinear optics
  • optical fibre communication
  • phase conjugation


Dive into the research topics of 'Enhancing the Signal Power Symmetry for Optical Phase Conjugation Using Erbium-Doped-Fibre-Assisted Raman Amplification'. Together they form a unique fingerprint.

Cite this