Optical Combiner Fiber Layout to Limit Fusion-Splice Deformation

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Solution Overview

Problem

Existing optical combiners experience deformation in the cross section of first optical fibers due to fusion-splicing, leading to beam quality deterioration when light propagates through the combiner.

Innovation Solution

The optical combiner design includes a first optical fiber with a core and cladding made of materials with higher softening temperatures, positioned in the center of the bundle, and fusion-splicing to minimize deformation during the fusion process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If fusion-splicing is performed to join optical fiber bundle and second optical fiber, then connection strength and optical coupling are improved, but cross-sectional deformation of first optical fibers occurs leading to beam quality deterioration

Engineering Contradiction:
Improveconnection strengthVSAvoidcross-sectional shape precision
Core Design Contradiction:
StrengthVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by controlling the heating temperature and duration during fusion-splicing to optimize the balance between achieving adequate connection strength and minimizing cross-sectional deformation of the optical fibers. By adjusting these thermal parameters, the invention resolves the contradiction between strong bonding and shape preservation.

Inventive Principle:
Principle #35Parameter changes

2Reliability

If fusion-splicing is performed to prevent gaps between first optical fibers, then light leakage is prevented, but beam quality deteriorates due to fiber deformation

Engineering Contradiction:
Improvelight leakage preventionVSAvoidcross-sectional shape precision
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The patent uses parameter changes by optimizing the fusion-splicing temperature and time parameters to achieve complete gap closure between optical fibers while minimizing thermal deformation. This resolves the contradiction between ensuring light-tight connections and maintaining fiber cross-sectional precision for beam quality.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If external heating is applied to form fused portion, then gaps between fibers are eliminated, but cross-sectional deformation occurs

Engineering Contradiction:
Improvegap eliminationVSAvoidcross-sectional shape
Core Design Contradiction:
ReliabilityVSShape

Solution Approach 1:

The patent applies parameter changes by carefully controlling the heating temperature profile and exposure time during the fusion process. This enables complete elimination of gaps between optical fibers while minimizing thermal-induced cross-sectional deformation, thus resolving the contradiction between gap closure and shape preservation.

Inventive Principle:
Principle #35Parameter changes

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

Reduces deformation in the cross section of the first optical fiber, enhancing beam quality and coupling efficiency, and minimizing light leakage.

Implementation Method 1

an end surface of the optical fiber bundle and an end surface of the second optical fiber are joined together by fusion-splicing

Methodology Applied
Scientific EffectFusion-splicing: Welding

Implementation Method 2

When the fused portion is formed, the optical fiber bundle is externally heated so that the first optical fibers are each fused

Methodology Applied
Scientific EffectExternal heating: Heating

Implementation Method 3

This causes a cross section of each of the first optical fibers to deform from a circular shape, which is the shape before fusion

Methodology Applied
Scientific EffectThermal deformation: Deformation

Data Source

PatentEP4012852B1Optical combiner, laser device, and method for manufacturing optical combiner
Publication Date: 2025.11.19 FUJIKURA LTD
  • EP4012852B1 patent drawingFigure 1~2(b)
  • EP4012852B1 patent drawingFigure 3~4

AI summary

In an optical combiner, deformation in the cross section of a predetermined first optical fiber is reduced more than in conventional optical combiners. The optical combiner (10) includes: an optical fiber bundle (11) formed by a plurality of first optical fibers (111 to 117); and a second optical fiber (12) having a diameter equal to or larger than the diameter of the optical fiber bundle (11). The plurality of first optical fibers (111 to 117) include a predetermined first optical fiber (117) and the other first optical fibers (111 to 116), the predetermined first optical fiber (117) being composed of one or more materials having higher softening temperatures than one or more materials for the other first optical fibers (111 to 116).