{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,21]],"date-time":"2026-05-21T01:47:37Z","timestamp":1779328057789,"version":"3.51.4"},"reference-count":49,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2024,7,15]],"date-time":"2024-07-15T00:00:00Z","timestamp":1721001600000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Innovation Program for Quantum Science and Technology","award":["2021ZD0301300"],"award-info":[{"award-number":["2021ZD0301300"]}]},{"name":"Innovation Program for Quantum Science and Technology","award":["62350001"],"award-info":[{"award-number":["62350001"]}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["2021ZD0301300"],"award-info":[{"award-number":["2021ZD0301300"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China","doi-asserted-by":"publisher","award":["62350001"],"award-info":[{"award-number":["62350001"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>In this paper, we investigate the impact of classical optical communications in quantum key distribution (QKD) over hollow-core fiber (HCF), multi-core fiber (MCF) and single-core fiber (SCF) and propose wavelength allocation schemes to enhance QKD performance. Firstly, we theoretically analyze noise interference in QKD over HCF, MCF and SCF, such as spontaneous Raman scattering (SpRS) and four-wave mixing (FWM). To mitigate these noise types and optimize QKD performance, we propose a joint noise suppression wavelength allocation (JSWA) scheme. FWM noise suppression wavelength allocation and Raman noise suppression wavelength allocation are also proposed for comparison. The JSWA scheme indicates a significant enhancement in extending the simultaneous transmission distance of classical signals and QKD, reaching approximately 100 km in HCF and 165 km in MCF under a classical power per channel of 10 dBm. Therefore, MCF offers a longer secure transmission distance compared with HCF when classical signals and QKD coexist in the C-band. However, when classical signals are in the C-band and QKD operates in the O-band, the performance of QKD in HCF surpasses that in MCF. This research establishes technical foundations for the design and deployment of QKD optical networks.<\/jats:p>","DOI":"10.3390\/e26070601","type":"journal-article","created":{"date-parts":[[2024,7,15]],"date-time":"2024-07-15T14:15:49Z","timestamp":1721052949000},"page":"601","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":10,"title":["Enhanced Coexistence of Quantum Key Distribution and Classical Communication over Hollow-Core and Multi-Core Fibers"],"prefix":"10.3390","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0000-0001-5602-2928","authenticated-orcid":false,"given":"Weiwen","family":"Kong","sequence":"first","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-0235-2507","authenticated-orcid":false,"given":"Yongmei","family":"Sun","sequence":"additional","affiliation":[{"name":"The State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Tianqi","family":"Dou","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuheng","family":"Xie","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhenhua","family":"Li","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yaoxian","family":"Gao","sequence":"additional","affiliation":[{"name":"The State Key Laboratory of Information Photonics and Optical Communications, School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Qi","family":"Zhao","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Na","family":"Chen","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Wenpeng","family":"Gao","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yuanchen","family":"Hao","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Peizhe","family":"Han","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yang","family":"Liu","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianjun","family":"Tang","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102200, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2024,7,15]]},"reference":[{"key":"ref_1","unstructured":"Bennett, C.H., and Brassard, G. 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