Optical Fiber With Resin Cladding And Quartz Support Layer

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Solution Overview

Problem

Optical fibers with a quartz core and fluorine-doped quartz cladding are prone to collapse during fusion or polishing, leading to non-uniform laser beam irradiation intensities due to the brittleness of the cladding, which compromises the maintenance of a rectangular cross-sectional shape.

Innovation Solution

An optical fiber design featuring a quartz core with a rectangular cross section, a low-refractive-index cladding made of resin with a circular outer shape, and a quartz support layer surrounding the cladding, along with a high-refractive-index protection layer, which maintains the rectangular shape and ensures uniform laser beam irradiation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a two-layer structure with fluorine-doped quartz cladding is used, then the refractive index difference between core and cladding is improved, but the cladding becomes more brittle and prone to collapse during fusion or polishing

Engineering Contradiction:
Improverefractive index differenceVSAvoidcladding strength
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

The patent applies composite materials by combining resin and quartz in a three-layer structure. The resin cladding provides mechanical strength and flexibility to prevent collapse during fusion or polishing, while the quartz support layer maintains the required refractive index difference for optical performance. This composite approach resolves the contradiction between optical performance and mechanical strength.

Inventive Principle:
Principle #40Composite materials

2Illumination intensity

If the cladding is made more brittle to achieve lower refractive index, then the refractive index contrast is improved, but the rectangular cross-sectional shape of the core collapses during processing

Engineering Contradiction:
Improverefractive index contrastVSAvoidrectangular cross-sectional shape
Core Design Contradiction:
Illumination intensityVSShape

Solution Approach 1:

The patent applies beforehand cushioning by introducing a quartz support layer that surrounds the resin cladding and provides mechanical support to the core. This support layer prevents the collapse of the rectangular cross-sectional shape during fusion or polishing processes, while allowing the resin cladding to maintain its lower refractive index for optimal optical performance.

Inventive Principle:
Principle #11Beforehand cushioning (Prior cushioning)

3Illumination intensity

If mode scrambling is performed by winding the optical fiber, then uniform light intensity distribution is achieved, but the optical fiber may be broken and the device size increases

Engineering Contradiction:
Improveuniform light intensity distributionVSAvoidoptical fiber integrity
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent applies parameter changes by modifying the structural parameters of the optical fiber - specifically creating a three-layer structure with a quartz core, resin cladding, and quartz support layer. This structural parameter change enables the fiber to maintain its integrity during mode scrambling operations while achieving uniform light intensity distribution, eliminating the need for external winding devices and improving reliability.

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

The design maintains uniform laser beam irradiation intensities while preventing cladding collapse, reducing damage from high-energy laser beams and enhancing the optical fiber's structural integrity.

Implementation Method 1

a low-refractive-index cladding surrounding the core, having a circular outer cross-sectional shape, and made of resin

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Implementation Method 2

a core having a rectangular cross section and made of quartz... the distribution of the intensities of a laser beam at the spot irradiated with the laser beam corresponds to a Gaussian distribution

Methodology Applied
Scientific EffectRectangular cross-section geometry: Geometry

Data Source

PatentEP2230540B1Optical fiber
Publication Date: 2019.07.31 MITSUBISHI CABLE INDUSTRIES LTD
  • EP2230540B1 patent drawingFigure 1
  • EP2230540B1 patent drawingFigure 2
  • EP2230540B1 patent drawingFigure 3

AI summary

An optical fiber includes a core (1a) having an oblong rectangular or square cross section and made of quartz, a cladding (2) surrounding the core (1a), having a circular outer cross-sectional shape, having a lower refractive index than the core (1a), and made of resin, and a support layer (3) surrounding the cladding (2) and made of quartz.