Multicore Fiber Rotational Alignment via D-Shape Ferrules

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Solution Overview

Problem

High-density multifiber connectors for multicore optical fibers are expensive to produce due to the need for precise control of the polishing process to ensure coplanarity, leading to high production costs and bulky, inflexible ribbon cordages.

Innovation Solution

The use of multicore fibers with D-shaped, double D-shaped, or polygonal geometries and corresponding ferrules with guide holes of various shapes to facilitate rotational alignment, along with alignment fixtures like ramps, tapered slots, side-entry slots, and wedges, ensures precise rotational alignment of fibers within ferrules, reducing the need for precise polishing and increasing production efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If standard single-core fibers are terminated into 2D-array MT ferrules to achieve high-density configurations, then fiber density is improved, but manufacturing cost increases significantly due to expensive ferrules and precise polishing requirements

Engineering Contradiction:
Improvefiber densityVSAvoidmanufacturing cost
Core Design Contradiction:
Quantity of substanceVSEase of manufacture

Solution Approach 1:

The patent replaces expensive molded MT ferrules with inexpensive precision-machined ferrules made from materials like stainless steel, aluminum, or ceramic. These ferrules can be mass-produced using conventional machining techniques, dramatically reducing the cost per unit while maintaining the necessary precision for high-density fiber termination.

Inventive Principle:
Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent introduces D-shaped multicore fibers with asymmetric geometry to enable automatic rotational alignment within the ferrule. The flat side of the D-shaped fiber engages with a corresponding flat surface or ramp in the ferrule, eliminating the need for complex polishing procedures and ensuring consistent coplanarity across all fiber ends.

Inventive Principle:
Principle #4Asymmetry

2Reliability

If precise control of polishing process is implemented to ensure coplanarity in 2D-array ferrules, then connection reliability is improved, but production time and cost increase

Engineering Contradiction:
Improveconnection reliabilityVSAvoidproduction efficiency
Core Design Contradiction:
ReliabilityVSProductivity

Solution Approach 1:

The patent incorporates alignment features directly into the ferrule design during manufacturing, such as precision-machined ramps, flat surfaces, or mechanical stops that pre-align the D-shaped fibers before insertion. This preliminary alignment action eliminates the need for time-consuming post-assembly polishing operations while ensuring consistent coplanarity and connection reliability.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The D-shaped fiber geometry combined with corresponding features in the ferrule creates a self-aligning system. When the fiber is inserted, the asymmetric shape automatically orients itself correctly through mechanical engagement with ramps or flat surfaces, ensuring proper rotational alignment and coplanarity without requiring external polishing or adjustment operations.

Inventive Principle:
Principle #25Self-service

3Quantity of substance

If fiber ribbons are stacked to produce ribbon cordages for 2D configurations, then fiber density is improved, but package size increases and flexibility decreases

Engineering Contradiction:
Improvefiber densityVSAvoidflexibility
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The patent transitions from stacking multiple flat ribbons in a bulky 3D arrangement to laying D-shaped multicore fibers flat in a single-plane configuration. The fibers are arranged side-by-side within a unified ferrule structure, maintaining high density while eliminating the layered stacking that causes bulk and reduces flexibility in traditional ribbon assemblies.

Inventive Principle:
Principle #17Another dimension (Dimensionality change)

Data Source

PatentEP2548068B1Multifiber connectors for multicore optical fiber cables
Publication Date: 2020.05.27 OFS FITEL LLC
  • EP2548068B1 patent drawingFigure 1A~1B
  • EP2548068B1 patent drawingFigure 2A~2C
  • EP2548068B1 patent drawingFigure 3~4

AI summary

Structures and techniques are described relating to the alignment of m?lticore libers within a multiilber connector. These structures and techniques include: muhicore fibers having a number of different shapes, including, for example, circular, elliptical, D-shapecL double D-shaped. and polygonal; muitifiber ferrules, having a plurality of fiber guide holes therein of various shapes; alignment fixtures for aligning muhicore fibers within muitifiber ferrules: and various muiticore fiber alignment techniques.