Coupling dynamics in multicore fibers: a comprehensive review of weakly-coupled and strongly-coupled MCF architectures for space-division multiplexing
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Shivani Goyal
Abstract
Multicore fibers (MCF) can overcome the capacity limitations of the network by enabling space-division multiplexing (SDM). Based on inter-core interaction, classification puts the MCFs into two groups. The first group is weakly-coupled (WC) MCFs. The second group is strongly-coupled (SC) MCFs. WC-MCFs are the weakly-coupled MCFs that minimize crosstalk through optimized core spacing and refractive-index engineering. Many researchers consider the independent transmission channels suitable for long-haul networks, high-capacity optical links, and emerging 5G/6G fronthaul deployment due to their stability and compatibility with existing infrastructure. Recent research highlights the complementary nature of WC and SC designs: WC-MCF is better for low-crosstalk independent-channel long-haul and practical deployment, while SC-MCF is better for maximizing spatial-spectral capacity and petabit-class core transport. In terms of capacity, strongly coupled MCF (SC-MCF) is better because its supermode-based spatial multiplexing supports far higher spatial channel counts and ultra-high petabit-class throughput compared to weakly coupled MCF.
Acknowledgments
The authors would like to thank their respective institutions for providing the necessary support and infrastructure for this research.
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Research ethics: This study did not involve any experiments with human participants or animals and thus did not require ethical approval.
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Informed consent: Not applicable. No human participants were involved in this research.
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Author contributions: Shivani Goyal analyzed the data and drafted the manuscript. She reviewed the final version.
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Use of Large Language Models, AI and Machine Learning Tools: ChatGPT was used solely for refining the language and grammar of the manuscript. No AI tools were used for data analysis or generating scientific content.
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Conflict of interest: The authors declare no conflict of interest.
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Research funding: None declared.
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Data availability: Not applicable.
References
1. Yang, H, Wang, S, Peng, D, Qin, Y, Fu, S. Optically powered 5G WDM fronthaul network with weakly-coupled multicore fiber. Opt Express 2022;30:19795–804. https://doi.org/10.1364/oe.457347.Suche in Google Scholar PubMed
2. Essiambre, R, Tkach, R. Capacity trends and limits of optical communication networks. Proc IEEE 2012;100:1035–55. https://doi.org/10.1109/jproc.2012.2182970.Suche in Google Scholar
3. Richardson, DJ, Fini, JM, Nelson, LE. Space-division multiplexing in optical fibres. Nat Photonics 2013;7:354–62. https://doi.org/10.1038/nphoton.2013.94.Suche in Google Scholar
4. Saitoh, K, Matsuo, S. Multicore fiber technology for high-capacity optical communication. IEICE Trans Electron 2015;E98-C:1191–202.Suche in Google Scholar
5. Jain, V, Bhatia, R. A survey on machine learning schemes for fiber nonlinearity mitigation in radio over fiber system. J Opt Commun 2024;45:s1157–63. https://doi.org/10.1515/joc-2022-0306.Suche in Google Scholar
6. Hayashi, T. Characteristics of uncoupled multi-core fibers for ultra-long-haul transmission. In: European Conference on Optical Communication (ECOC). London, UK: IEEE (Institute of Electrical and Electronics Engineers); 2013.Suche in Google Scholar
7. Wang, S. Performance evaluation of weakly coupled multicore fibers for SDM systems. J Lightwave Technol 2019;37:455–62.Suche in Google Scholar
8. Mizuno, T. 114-space-division-multiplexed transmission over 9.8 km six-mode 19-core fiber. Opt Express 2014;22:13221–7.Suche in Google Scholar
9. Soma, D. 2.05 Peta-bit/s super-nyquist-WDM SDM transmission using 9.8-km 6-mode 19-core fiber in full C band. In: European conference on optical communication (ECOC). Valencia, Spain: IEEE (Institute of Electrical and Electronics Engineers); 2015.10.1109/ECOC.2015.7341686Suche in Google Scholar
10. Jain, V, Bhatia, R. Review on nonlinearity effect in radio over fiber system and its mitigation. J Opt Commun 2023;44:s1661–s16. https://doi.org/10.1515/joc-2021-0044.Suche in Google Scholar
11. Essiambre, R, Tkach, RW, Winzer, PJ, Foschini, GJ, Goebel, B. Capacity limits of optical fiber networks. J Lightwave Technol 2010;28:662–701. https://doi.org/10.1109/jlt.2009.2039464.Suche in Google Scholar
12. Awaji, Y. Review of space-division multiplexing technologies in optical communications. IEICE Trans Commun 2019;E102-B:1–16. https://doi.org/10.1587/transcom.2017ebi0002.Suche in Google Scholar
13. Hayashi, T, Taru, T, Shimakawa, O, Sasaki, T, Sasaoka, E. Characterization of crosstalk in ultra-low-crosstalk multi-core fiber. J Lightwave Technol 2012;30:583–9. https://doi.org/10.1109/jlt.2011.2177810.Suche in Google Scholar
14. Sillard, P, Bigot-Astruc, M, Molin, D. Heterogeneous multicore fiber for SDM transmission. In: Optical Fiber Communication Conference (OFC). CA, USA: Anaheim; 2014.Suche in Google Scholar
15. T Hayashi. Ultra-low-crosstalk multi-core fiber feasible to ultra-long-haul transmission, OFC, Los Angeles, CA, USA; 2011.10.1364/NFOEC.2011.PDPC2Suche in Google Scholar
16. Takenaga, K. Large-effective-area 10-core fiber with low crosstalk. Opt Lett 2011;36:4626–8.10.1364/OL.36.004626Suche in Google Scholar PubMed
17. Goyal, S, Jindal, PK, Jain, V. Advancing PON performance via multi-core multi-mode fiber. J Opt 2024;26:1–8. https://doi.org/10.1007/s12596-024-02240-y.Suche in Google Scholar
18. Shao, P, Li, Z, Ma, L, Wang, C, Li, S, Li, J, et al.. Weakly coupled graded index heterogeneous nineteen-core few-mode fiber. Opt Express 2023;31:10473–88. https://doi.org/10.1364/oe.485965.Suche in Google Scholar PubMed
19. Goyal, S, Jain, V. Improved crosstalk real-time monitoring in multi-core multi-mode fibres with additional control and supervision channels. J Opt 2025:1–9. https://doi.org/10.1007/s12596-025-02900-7.Suche in Google Scholar
20. Sillard, P. Few-mode multicore fiber for mode and core multiplexed transmission. In: Optical Fiber Communication Conference (OFC). Los Angeles, USA: OSA (Optical Society of America); 2011.Suche in Google Scholar
21. Mizuno, T. 114-space-division-multiplexed transmission over 9.8 km 6-mode 19-core fiber. Opt Express 2014;22:32914–22.Suche in Google Scholar
22. Goyal, S, Jain, V. Performance assessment of upstream and downstream losses in a passive optical network utilizing a 19-core multicore fiber. J Opt 2024;53:3821–8. https://doi.org/10.1007/s12596-023-01573-4.Suche in Google Scholar
23. Goyal, S, Kaur, B, Jindal, PK, Pahuja, H. Cutting-edge space-division multiplexing using multi-core and multi core-multi-mode fibers in passive optical networks. J Opt 2025:1–6. https://doi.org/10.1007/s12596-025-02546-5.Suche in Google Scholar
24. Jain, S. Challenges and DSP requirements for strongly coupled spatial multiplexing fibers. IEEE Photon Technol Lett 2021;33:739–42.Suche in Google Scholar
25. Garg, D, Nain, A. Analysis and mitigation of photodiode non-linearity under the influence of optical modulator in multitone RoF link. J Opt 2022;51:482–90. https://doi.org/10.1007/s12596-021-00794-9.Suche in Google Scholar
26. van den Hout, M, Luís, S, Puttnam, BJ, Di Sciullo, G, Hayashi, T, Inoue, A, et al.. Reaching the pinnacle of high-capacity optical transmission using a standard cladding diameter coupled-core multi-core fiber. Nat Commun 2025;16:3833. https://doi.org/10.1038/s41467-025-59037-1.Suche in Google Scholar PubMed PubMed Central
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