Compact Backbone Fiber Cable With High Packing Density

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Solution Overview

Problem

Existing optical fiber cables for horizontal backbone applications face challenges in achieving high packing density and meeting tensile load requirements while maintaining a compact diameter, as the inclusion of reinforcing yarns limits space for additional fibers.

Innovation Solution

Optical fiber cables are designed with optical fibers having a strain greater than 0.6% under standard installation tensile load, combined with a reduced amount of reinforcing yarns, allowing for a packing density of greater than 1.25 fibers per square millimeter, and enclosed in a jacket to maintain mechanical protection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If the fiber packing density is increased to accommodate bandwidth demands, then the number of optical fibers that can be included increases, but the space for aramid reinforcing yarn decreases

Engineering Contradiction:
Improvefiber packing densityVSAvoidtensile strength
Core Design Contradiction:
Quantity of substanceVSStrength

Solution Approach 1:

The patent applies parameter changes by transitioning from conventional 125-micron glass cladding diameter fibers to smaller 80-micron or 90-micron fibers. This dimensional parameter change reduces the cross-sectional area occupied by each fiber, thereby increasing the packing density without proportionally reducing the space available for reinforcing yarn. The smaller fiber diameter allows more fibers to be packed into the same cable cross-section while maintaining adequate space for tensile strength elements.

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The patent employs composite materials by combining smaller diameter optical fibers with aramid reinforcing yarn in a integrated cable structure. The composite construction allows optimized space utilization where the smaller fibers occupy less space, and the aramid yarn provides the necessary tensile strength. This composite approach enables simultaneous achievement of high fiber count and adequate mechanical strength within compact cable dimensions.

Inventive Principle:
Principle #40Composite materials

2Volume of moving object

If the cable diameter is reduced to fit existing rack and tray capacity, then the cable becomes more compact, but the space for reinforcing yarn and fiber installation decreases

Engineering Contradiction:
Improvecable diameterVSAvoidcable assembly feasibility
Core Design Contradiction:
Volume of moving objectVSEase of manufacture

Solution Approach 1:

The patent reduces cable diameter by changing the fiber cladding diameter parameter from 125 microns to 80-90 microns. This parameter change enables compact cable construction that fits within existing rack and tray spaces while maintaining adequate cross-sectional area for reinforcing yarn and installation feasibility. The smaller fiber size allows the cable to meet space constraints without compromising manufacturing capability.

Inventive Principle:
Principle #35Parameter changes

3Strength

If more aramid reinforcing yarn is included to meet tensile load requirements, then the tensile strength increases, but the fiber packing density decreases

Engineering Contradiction:
Improvetensile load strengthVSAvoidfiber packing density
Core Design Contradiction:
StrengthVSQuantity of substance

Solution Approach 1:

The patent resolves this contradiction by changing the fiber diameter parameter to a smaller size (80-90 microns versus 125 microns). This parameter change reduces the space requirement for each fiber, allowing increased fiber packing density while preserving sufficient space for the necessary amount of aramid reinforcing yarn. The smaller fiber size enables both high fiber count and adequate tensile strength elements to coexist within the cable cross-section.

Inventive Principle:
Principle #35Parameter changes

Data Source

PatentEP3388878B1Compact horizontal backbone cables for premises optical cabling applications
Publication Date: 2026.03.25 OFS FITEL LLC
  • EP3388878B1 patent drawingFigure 1
  • EP3388878B1 patent drawingFigure 2

AI summary

A optical fiber cable includes optical fibers, reinforcing yarns, and a jacket. Each optical fiber has a fiber strain greater than 0.6 percent under standard installation tensile load. The jacket encloses the optical fibers and reinforcing yarns at a packing density greater than about 1.25 fibers per square millimeter. The combined effect of optical fibers having a fiber strain greater than 0.6 percent under standard installation tensile load and a small amount of reinforcing yarn provides the optical fiber cable with high proof strain, compact diameter, and high packing density.