# How a Multi-Core Optical Fiber Reduces Signal Interference > 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. - **Patent:** US 11480727 - **Original title:** Multi-core optical fiber - **Owner:** Sumitomo Electric Industries - **Granted:** 2022 - **Status:** Active - **Times cited:** 2 - **Field:** telecommunications, semiconductors, consumer_electronics ## 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. ## The clever bit The clever part is the specific design of alternating 'first' and 'second' core portions within a linear array, each with carefully controlled refractive index differences and trench layer dimensions. This precise engineering, particularly the 'offset' and 'reversed' refractive index relationship between the inner cladding and common cladding for adjacent cores, is what allows the fiber to minimize crosstalk and maintain signal integrity even when multiple data streams run very close together. ## Real-world examples 1. Data center interconnects 2. High-density fiber optic cables 3. 5G network infrastructure 4. Short-reach optical communication modules ## Why it matters This patent addresses a key challenge in high-density data transmission: how to pack more data paths into a single fiber without signals interfering with each other. By carefully designing the core arrangements and refractive index profiles, this fiber aims to offer both cost-effectiveness and good compatibility for short-distance optical links. This is crucial for applications like data centers or 5G networks where space is limited and high bandwidth is essential. ## Frequently asked questions ### What does How a Multi-Core Optical Fiber Reduces Signal Interference cover? 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. ### Who owns patent US 11480727? Sumitomo Electric Industries owns this patent, granted in 2022. ### When does this patent expire? This patent is expected to expire on June 29, 2040, when the invention enters the public domain. ### What is patent US 11480727 cited by? This patent has been cited by 2 later patents that build on its ideas. ### What problem does this patent solve? This patent addresses a key challenge in high-density data transmission: how to pack more data paths into a single fiber without signals interfering with each other. By carefully designing the core arrangements and refractive index profiles, this fiber aims to offer both cost-effectiveness and good compatibility for short-distance optical links. This is crucial for applications like data centers or 5G networks where space is limited and high bandwidth is essential. ### What does this patent NOT cover? Multi-core optical fibers that do not have at least four core portions arranged in a straight line. **Full plain-English explainer:** https://patentbrief.org/patent/us/11480727/multi-core-optical-fiber **Original patent:** https://patents.google.com/patent/US11480727 --- _Source: PatentBrief — https://patentbrief.org. Patent facts are from public records; the plain-English explanation is PatentBrief's._ ## Related patents Semantically similar inventions in the PatentBrief corpus: - [How a Special Fiber Stub Cleans Up Light Signals](https://patentbrief.org/patent/us/7267494/fiber-stub-for-cladding-mode-coupling-reduction) — 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. - [Stacking Chips with Light-Guiding Plastic Wires](https://patentbrief.org/patent/us/12181722/structures-and-process-flow-for-integrated-photonic-electric-ic-package-by-using) — TSMC's patent describes a method for building advanced chip packages that combine electrical and light-based circuits using polymer waveguides and an integrated fan-out redistribution layer for faster communication. - [A Stamped Mirror to Connect Optical Fibers to Tiny Light Chips](https://patentbrief.org/patent/us/12422629/optical-connection-of-optical-fibers-to-grating-couplers) — This patent describes a method to precisely connect a standard optical fiber to a tiny light-based computer chip (a photonic integrated circuit) using a specially shaped, stamped mirror that redirects and reshapes the light. - [How Chips Talk Fast with Light Inside a Circuit Board](https://patentbrief.org/patent/us/20260003141/package-having-component-carrier-and-embedded-optical-and-electric-chips-with-ho) — This patent describes a way to embed light-based (optical) and electricity-based (electric) computer chips directly next to each other within a circuit board, allowing them to communicate very quickly along a flat, horizontal path. - [A Sealed, Stamped Metal Assembly for Guiding Light in Fiber Optics](https://patentbrief.org/patent/us/10761280/hermetic-optical-subassembly) — This patent describes a tiny, sealed optical assembly that uses precisely shaped metal parts and mirrors to guide light signals between a fiber optic cable and an electronic light-emitting or light-sensing device without needing lenses between the main mirrors.