{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T18:46:28Z","timestamp":1773081988947,"version":"3.50.1"},"reference-count":22,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T00:00:00Z","timestamp":1773014400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Science and Technology Innovation 2030 Major Project","award":["2021ZD0301300"],"award-info":[{"award-number":["2021ZD0301300"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Entropy"],"abstract":"<jats:p>Based on mode crosstalk theory, this paper develops a spontaneous Raman scattering (SpRS) model for the quantum-classical coexistence system using few-mode fiber (FMF) integrated with wavelength-division multiplexing (WDM) and spatial-division multiplexing (SDM). Through numerical calculations, the influence degrees of three factors (mode coupling, the number of modes and wavelengths) on SpRS are analyzed. The investigation identifies the dominant contributors to SpRS and reveals their relative impact magnitudes. Based on these results, a ring-assisted FMF is proposed to mitigate noise impacts on quantum signals. The numerical results show that the optimized FMF enhances quantum signal transmission distance by up to 41.5%.<\/jats:p>","DOI":"10.3390\/e28030309","type":"journal-article","created":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T11:06:52Z","timestamp":1773054412000},"page":"309","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Simultaneous Transmission of Discrete-Variable Quantum Key Distribution and Classical Optical Communication in Few-Mode Fiber"],"prefix":"10.3390","volume":"28","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-6370-5052","authenticated-orcid":false,"given":"Qi","family":"Zhao","sequence":"first","affiliation":[{"name":"China Telecom Research Institute, Beijing 102209, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Gang","family":"Wang","sequence":"additional","affiliation":[{"name":"Group Cloud and Network Development Department, China Telecom, Beijing 100033, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Li","family":"Pei","sequence":"additional","affiliation":[{"name":"Key Laboratory of All Optical Network and Advanced Telecommunication Network of Ministry of Education, Beijing Jiaotong University, Beijing 100044, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jianjun","family":"Tang","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102209, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0008-5965-3213","authenticated-orcid":false,"given":"Yuheng","family":"Xie","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102209, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Zhenhua","family":"Li","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102209, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yang","family":"Liu","sequence":"additional","affiliation":[{"name":"China Telecom Research Institute, Beijing 102209, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,9]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1038\/nature23655","article-title":"Satellite-to-ground quantum key distribution","volume":"549","author":"Liao","year":"2017","journal-title":"Nature"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"052333","DOI":"10.1103\/PhysRevA.89.052333","article-title":"Protocol choice and parameter optimization in decoy-state measurement-device-independent quantum key distribution","volume":"89","author":"Xu","year":"2014","journal-title":"Phys. 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