Optical-Fiber Ferrule Liquid Index Matching for Deformation Loss

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Solution Overview

Problem

Existing optical-fiber ferrules experience increased transmission loss due to deformation caused by environmental changes, such as high temperature and humidity, leading to peeling of optical fiber end surfaces from the adhesive-filling section's inner wall.

Innovation Solution

An optical-fiber-attached ferrule is designed with a filling section filled with a liquid refractive index-matching material, where the optical fiber end surface abuts an opposed surface within the ferrule, reducing deformation and maintaining physical contact, thereby minimizing transmission loss. The liquid refractive index-matching material has water repellency and viscosity within a specific range to prevent overflow and ensure effective filling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If adhesive is filled in the adhesive-filling section to fix the optical fibers, then the optical fibers are fixed to the ferrule, but the ferrule deforms due to environmental changes causing end surfaces of fibers to peel off from the abutting surface

Engineering Contradiction:

Improvefixing strength of optical fibersVSAvoidtransmission loss

Core Design Contradiction:

StrengthVSReliability

Solution Approach 1:

The patent changes the physical state of the filling material from solid (adhesive) to liquid (refractive index-matching material). This parameter change allows the material to flow into gaps created by thermal deformation and maintain optical contact, resolving the contradiction between fixing strength and transmission loss reliability

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The liquid refractive index-matching material acts as an intermediary substance between the optical fiber end surfaces and the abutting surface. It fills gaps and maintains optical contact during thermal deformation, preventing peeling and reducing transmission loss while the adhesive provides structural fixing

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If the filling section is filled with liquid refractive index-matching material, then transmission loss is reduced upon deformation, but the material may overflow due to deformation

Engineering Contradiction:

Improvetransmission lossVSAvoidliquid material overflow

Core Design Contradiction:

ReliabilityVSLoss of substance

Solution Approach 1:

The patent uses a gel structure as a flexible containment shell for the liquid refractive index-matching material. The gel can deform with thermal expansion/contraction while containing the liquid material, preventing overflow while allowing the liquid to maintain optical contact and reduce transmission loss

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The patent creates a composite structure combining gel and liquid refractive index-matching materials. The gel provides structural containment and flexibility, while the liquid provides optical matching properties, together resolving the contradiction between preventing overflow and reducing transmission loss

Inventive Principle:

Principle #40Composite materials

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

This design reduces transmission loss by allowing the liquid refractive index-matching material to enter the gap between the optical fiber end surface and the abutting surface upon ferrule deformation, maintaining the material's physical properties and preventing peeling, thus achieving lower transmission loss compared to traditional adhesive-filling methods.

Implementation Method 1

the liquid refractive index-matching material enters between the optical fiber end surface and the abutting surface

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Implementation Method 2

the liquid refractive index-matching material has water repellency

Methodology Applied

Scientific EffectHydrophobicity: Hydrophobe

Data Source

PatentUS10209455B2Optical-fiber-attached ferrule and method of manufacturing the same

Publication Date: 2019.02.19 FUJIKURA LTD

AI summary

An optical-fiber-attached ferrule includes: an optical fiber hole into which an optical fiber is inserted; and a filling section filled with a liquid refractive index-matching material. The filling section internally includes an opening surface of the optical fiber hole and an opposed surface that is opposed to the opening surface, and the filling section is filled with the liquid refractive index-matching material while an end surface of the optical fiber inserted into the optical fiber hole abuts with the opposed surface