{
  "patent_number": "US 7267494",
  "country": "US",
  "title": "How a Special Fiber Stub Cleans Up Light Signals",
  "original_title": "Fiber stub for cladding mode coupling reduction",
  "summary": "This patent describes a short piece of optical fiber, called a fiber stub, designed to prevent unwanted light from escaping the fiber's core and interfering with data transmission by using a ferrule with a specific optical property.",
  "what_it_does": "The patent describes a \"fiber stub\" (Claim 1) used in optical devices like transceivers (Claim 18). This stub has an \"optical fiber\" with a \"core\" (where the main light signal travels) and a \"cladding\" (the layer surrounding the core). Crucially, the stub also includes a \"ferrule\" (a protective sleeve) made of a material, often glass (Claim 2), that has a \"refractive index\" greater than the cladding's refractive index (Claim 1). This difference causes unwanted \"cladding modes\" (light traveling in the cladding) to bend and refract into the ferrule and away from the core (Abstract). An optional \"absorbing layer\" on the ferrule's outer surface can then soak up this unwanted light (Claim 5), ensuring a cleaner signal is transmitted. For example, in a 10 Gigabit Ethernet transceiver (Claim 20), this stub helps maintain signal integrity over distances up to 300 meters.",
  "what_it_does_not_cover": [
    "Fiber stubs where the ferrule's refractive index is less than or equal to the cladding's refractive index.",
    "Optical fiber connections that do not use a ferrule with this specific refractive index relationship.",
    "Methods for reducing signal loss caused by factors other than cladding modes.",
    "Fiber stubs designed for multi-mode optical fibers where the primary signal travels within the cladding.",
    "Devices where the fiber stub is longer than about five millimeters (Claim 4)."
  ],
  "filed": "2006-01-31",
  "granted": "2007-09-11",
  "expires": "2026-01-31",
  "status": "expired",
  "holder": "Finisar",
  "holder_url": "https://patentbrief.org/company/finisar",
  "inventors": [
    {
      "name": "Yuri Vandyshev",
      "url": "https://patentbrief.org/inventor/yuri-vandyshev"
    },
    {
      "name": "Lewis B. Aronson",
      "url": "https://patentbrief.org/inventor/lewis-b-aronson"
    },
    {
      "name": "Hongyu Deng",
      "url": "https://patentbrief.org/inventor/hongyu-deng"
    }
  ],
  "times_cited": 81,
  "tags": [
    "telecommunications",
    "semiconductors"
  ],
  "abstract": "Fiber stub interface for reducing cladding mode light. The fiber stub can be implemented in an optical transmission device. The optical transmission device can be a transceiver that also includes an optical signal receiver. The fiber stub includes an optical fiber and a ferrule. The optical fiber includes both a core and a cladding. The ferrule includes a glass material with a refractive index that is greater than the refractive index of at least a portion of the optical fiber. As a result, the cladding modes are refracted into the ferrule and away from the core, thereby reducing the chance that they are transmitted to an external optical fiber. An absorptive layer can be applied to an outer surface of the ferrule to absorb the refracted cladding modes.",
  "url": "https://patentbrief.org/patent/us/7267494/fiber-stub-for-cladding-mode-coupling-reduction",
  "markdown_url": "https://patentbrief.org/patent/us/7267494/fiber-stub-for-cladding-mode-coupling-reduction/md",
  "google_patents_url": "https://patents.google.com/patent/US7267494",
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}