{
  "patent_number": "US 11480727",
  "country": "US",
  "title": "How a Multi-Core Optical Fiber Reduces Signal Interference",
  "original_title": "Multi-core optical fiber",
  "summary": "This patent describes a multi-core optical fiber designed for short-distance data transmission, featuring a specific linear arrangement of at least four cores with alternating designs to minimize signal leakage between them.",
  "what_it_does": "This multi-core optical fiber (MCF) includes several core portions, a shared outer layer called a common cladding, and a protective resin coating. Each core portion itself has a central core, an inner cladding, and a trench layer. The fiber is special because it has at least four core portions arranged in a straight line (a 'linear array group'), where these cores alternate between 'first' and 'second' types. These alternating core types are designed with specific differences: their trench layers have different outer radii, and their refractive index differences relative to the common cladding also vary. For example, the abstract notes that the inner cladding's refractive index is intentionally offset from the common cladding's refractive index, sometimes even reversing their typical magnitude relationship, to better contain light within each core and reduce crosstalk.",
  "what_it_does_not_cover": [
    "Multi-core optical fibers that do not have at least four core portions arranged in a straight line.",
    "Fibers where the core portions do not alternate between 'first' and 'second' types with differing trench layer outer radii.",
    "Fibers where the relative refractive index differences of adjacent core portions with respect to the common cladding do not differ by at least 0.001 Λ [%].",
    "Fibers that do not meet the specified outer diameters for the common cladding (124-181 μm) and resin coating (195-250 μm).",
    "Fibers that do not achieve the claimed performance metrics, such as a crosstalk of 0.01/km or less at specified bending radii.",
    "Fibers where the refractive index profile of the inner cladding and common cladding does not show the specific 'reversed' magnitude relationship for adjacent core portions."
  ],
  "filed": "2020-06-29",
  "granted": "2022-10-25",
  "expires": "2040-06-29",
  "status": "active",
  "holder": "Sumitomo Electric Industries",
  "holder_url": "https://patentbrief.org/company/sumitomo-electric-industries",
  "inventors": [
    {
      "name": "Tetsuya Hayashi",
      "url": "https://patentbrief.org/inventor/tetsuya-hayashi"
    }
  ],
  "times_cited": 2,
  "tags": [
    "telecommunications",
    "semiconductors",
    "consumer_electronics"
  ],
  "abstract": "An MCF according to one embodiment simultaneously achieves excellent economic rationality and high compatibility in short-distance optical transmission. The MCF includes a plurality of core portions, a common cladding, and a resin coating. Each of the core portions includes a core, an inner cladding, and a trench layer. At least four core portions arranged on a straight line have substantially the same relative refractive index difference between the core and the inner cladding. The refractive index profile of a first core portion and a second core portion adjacent to each other among the four core portions has a shape in which the refractive index of the inner cladding is offset with respect to the refractive index of the common cladding so that the magnitude relationship of the refractive index between the inner cladding and the common cladding is reversed.",
  "url": "https://patentbrief.org/patent/us/11480727/multi-core-optical-fiber",
  "markdown_url": "https://patentbrief.org/patent/us/11480727/multi-core-optical-fiber/md",
  "google_patents_url": "https://patents.google.com/patent/US11480727",
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