Optical Connection Structure with Refractive-Index Matching Material

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Solution Overview

Problem

Existing optical connection structures experience degradation in optical characteristics over time due to thermal influences, leading to gaps between multi-core fibers and optical fibers, which result in back reflections and insertion losses.

Innovation Solution

An optical connection structure that incorporates a refractive-index matching material applied in a sealed space between ferrules, allowing it to fill gaps caused by thermal recession of optical fibers, maintaining optical integrity through capillary action and precise alignment of fiber cores.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If optical fibers are fixed in ferrule with adhesive and butted against multi-core fiber, then optical connection is achieved, but thermal influences cause fiber recession and gap formation leading to back reflections and insertion losses

Engineering Contradiction:

Improveoptical connection stabilityVSAvoidthermal influence

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A refractive-index matching material is introduced as an intermediary substance between the optical fiber and multi-core fiber. This material fills the gap formed by thermal recession and has a refractive index that matches the optical fiber core, thereby eliminating back reflections and insertion losses while allowing the fibers to remain in their thermally affected positions

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The refractive index parameter of the matching material is specifically selected to match that of the optical fiber core. By changing and optimizing this physical parameter, the optical characteristics are maintained even when physical positions of fibers change due to thermal expansion or contraction

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If adhesive is packed flush with ferrule end surface, then fiber fixation is achieved, but thermal recession creates gaps that degrade optical characteristics

Engineering Contradiction:

Improvefiber alignment precisionVSAvoidoptical characteristic stability

Core Design Contradiction:

Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The refractive-index matching material is applied in advance to the ferrule end surface or inner hole before fiber assembly. This material acts as a cushioning layer that can accommodate future thermal recession by filling any gaps that may form, thereby preventing degradation of optical characteristics before they occur

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Adaptability or versatility

If gap forms between fibers due to thermal recession, then fiber movement is accommodated, but back reflections and insertion losses occur

Engineering Contradiction:

Improvethermal expansion accommodationVSAvoidback reflection

Core Design Contradiction:

Adaptability or versatilityVSObject-generated harmful factors

Solution Approach 1:

The refractive-index matching material serves as an optical intermediary that eliminates the harmful reflection effects at the gap interface. By matching the refractive index of the optical fiber core, it creates a gradual transition that prevents back reflections while still allowing physical gap formation due to thermal effects

Inventive Principle:

Principle #24Intermediary (Mediator)

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 solution effectively prevents degradation of back reflections and insertion losses, ensuring stable optical performance over time by immediately filling gaps with refractive-index matching material, even when optical fibers recess due to thermal influences.

Implementation Method 1

allowing it to fill gaps caused by thermal recession of optical fibers, maintaining optical integrity through capillary action

Methodology Applied

Scientific EffectCapillary action: Capillary Action

Data Source

PatentUS11914194B2Optical connection structure

Publication Date: 2024.02.27 SUMITOMO ELECTRIC INDUSTRIES LTD

AI summary

An optical connection structure includes a MCF, a first ferrule, a plurality of optical fibers, and a second ferrule. The MCF includes first cores and a first cladding. The first ferrule has a first inner hole and a first ferrule end surface. Each optical fiber optically connected to the MCF includes a second core and a second cladding. The second ferrule has a second inner hole housing tip parts of the optical fibers, and a second ferrule end surface. The second ferrule fixes the tip parts of the optical fibers in the second inner hole by an adhesive. The adhesive is packed in the second inner hole such that a surface of the adhesive is recessed from the second ferrule end surface into the second inner hole. A refractive-index matching material is applied in a space sealed by the first ferrule end surface and the second ferrule end surface.