In this paper, we review different designs of distributed Raman amplifiers which have been proposed to minimize the signal power profile asymmetry in mid-link optical phase conjugation systems. We demonstrate how the symmetrical signal power profiles along the fiber can be achieved using various distributed Raman amplification techniques in the single-span and more realistic multi-span circumstances. In addition, we show the theoretically predicted results of the Kerr nonlinear product reduction with different Raman techniques in mid-link optical phase conjugator systems, and then in-line/long-haul transmission performance using numerical simulations.
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Funding: This research was funded by the UK Engineering and Physical Sciences Research Council
(EPSRC) Grant EP/S003436/1 (PHOS), EP/V000969/1 (ARGON), EP/S016171/1(EEMC), the Polish
Ministry of Science and Higher Education Grant 12300051, EU Horizon 2020 Project 101008280,
RTI2018-097957-B-C33 (ECOSYSTEM) funded by Spanish MCIN/AEI/10.13039/501100011033, Research and innovation Programme SINFOTON2-CM (S2018/NMT-4326) co-financed by ESF funds,
and the National Natural Science Foundation of China Grant 61975027.
- Coherent fiber optic communications
- Optical phase conjugation
- Raman amplification