Fine-Diameter Optical Fiber Coating for Strength and Adhesion

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Solution Overview

Problem

Conventional optical fibers with reduced coating layers suffer from decreased strength and adhesive force, leading to deformation and damage under external stress, and difficulty in protecting the quartz layer.

Innovation Solution

A reduced-diameter low-loss optical fiber design featuring a quartz layer, an adhesive layer with a silane coupling agent, a first coating layer, and a second coating layer with reinforcing members, where the second coating layer matrix shares the same base material as the first coating layer, and includes nanotubes to enhance strength and adhesive force.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the thickness of the coating layer is reduced to decrease the diameter of the optical fiber, then the diameter of the optical fiber is reduced, but the strength of the optical fiber decreases

Engineering Contradiction:
Improvediameter of optical fiberVSAvoidstrength of optical fiber
Core Design Contradiction:
Volume of moving objectVSStrength

Solution Approach 1:

The patent applies composite materials by incorporating reinforcing members (such as nanotubes or glass fibers) into the coating layer to create a composite structure. This composite coating layer maintains the reduced diameter while significantly enhancing the tensile strength and mechanical properties of the optical fiber, resolving the contradiction between small diameter and high strength

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating a multi-layer coating structure where different layers have different functions. The first coating layer provides basic protection, while the second coating layer contains reinforcing members for enhanced strength. This localized functional differentiation allows the fiber to maintain small overall diameter while having specific regions optimized for strength

Inventive Principle:
Principle #3Local quality

2Volume of moving object

If the thickness of the coating layer is reduced to decrease the diameter of the optical fiber, then the diameter of the optical fiber is reduced, but the adhesive force between the coating layer and the quartz layer decreases

Engineering Contradiction:
Improvediameter of optical fiberVSAvoidadhesive force between coating layer and quartz layer
Core Design Contradiction:
Volume of moving objectVSForce

Solution Approach 1:

The patent applies the intermediary principle by introducing an adhesive layer between the quartz layer and the first coating layer. This adhesive layer acts as a mediator that enhances the bonding interface, ensuring strong adhesive force even when the overall coating layer thickness is reduced. The adhesive layer specifically addresses the interface adhesion problem without increasing the external diameter significantly

Inventive Principle:
Principle #24Intermediary (Mediator)

3Volume of moving object

If the thickness of the coating layer is reduced, then the diameter of the optical fiber is reduced, but the ability to protect the quartz layer from deformation and damage decreases

Engineering Contradiction:
Improvediameter of optical fiberVSAvoidprotection ability of coating layer
Core Design Contradiction:
Volume of moving objectVSReliability

Solution Approach 1:

The patent uses composite materials in the coating layer by incorporating reinforcing members (nanotubes, glass fibers, or aramid fibers) into the coating matrix. This composite structure provides enhanced mechanical strength, crack resistance, and protection against deformation, ensuring the quartz layer is adequately protected even with reduced overall coating thickness

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The patent implements local quality through a multi-layer coating system where the second coating layer contains reinforcing members specifically for enhanced protection. This localized reinforcement in the outer layer provides superior protection capability without significantly increasing the overall fiber diameter, as the reinforcement is concentrated where it is most needed

Inventive Principle:
Principle #3Local quality

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The design provides increased tensile and compressive strength, maintains strong adhesive force, and prevents micro-crack propagation, ensuring effective protection and flexibility of the optical fiber.

Implementation Method 1

the adhesive agent is a silane coupling agent which includes a first functional group and a second functional group, where the first functional group is connected to the second functional group through a chemical bond, the first functional group is bonded to the quartz layer through the chemical bond, and the second functional group is bonded to the first coating layer through the chemical bond

Methodology Applied
Scientific EffectChemical bonding: Chemical Bonding

Implementation Method 2

the second coating layer includes a second coating layer matrix and a plurality of reinforcing members, where the base material of the second coating layer matrix is the same as that of the first coating layer, and the plurality of reinforcing members are distributed in the second coating layer matrix, so as to increase a strength of the reduced-diameter low-loss optical fiber

Methodology Applied
Scientific EffectNanotube reinforcement: Carbon Nanotubes

Data Source

PatentEP4692873A1Fine-diameter low-loss optical fiber and optical cable
Publication Date: 2026.02.11 ZHONGTIAN TECH FIBER OPTICS
  • EP4692873A1 patent drawingFigure 1~2
  • EP4692873A1 patent drawingFigure 3~4
  • EP4692873A1 patent drawingFigure 5~6

AI summary

The present application provides a reduced-diameter low-loss optical fiber and an optical cable. The reduced-diameter low-loss optical fiber includes a quartz layer, an adhesive layer, a first coating layer, and a second coating layer which are sequentially provided from inside to outside along a radial direction of the reduced-diameter low-loss optical fiber; where the adhesive layer is configured to increase an adhesive force between the first coating layer and the quartz layer; the first coating layer is configured to protect the quartz layer; and the second coating layer includes a second coating layer matrix and a plurality of reinforcing members, a base material of the second coating layer matrix is the same as that of the first coating layer, and the plurality of reinforcing members are distributed in the second coating layer matrix, so as to increase a strength of the reduced-diameter low-loss optical fiber. In the reduced-diameter low-loss optical fiber provided by the present application, the strength of the reduced-diameter low-loss optical fiber is relatively large, and the adhesive force between the coating layer and the quartz layer in the reduced-diameter low-loss optical fiber is relatively strong.