Fatigue-Resistant Optical Fiber with Laser-Induced Scattering Sites

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Solution Overview

Problem

Existing optical fibers with side irradiation capabilities are susceptible to mechanical failure due to reduced bending strength and increased fatigue, and current manufacturing techniques do not produce reliable and efficient side-illuminating fibers.

Innovation Solution

The development of a strong, fatigue-resistant optical fiber with enhanced side irradiation is achieved by creating scattering sites within the core section using femtosecond laser pulses, forming a tubular structure with varying refractive index, and incorporating a solid innermost section for sensing capabilities.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If conventional techniques (removing cladding, micromachining, tapering) are used to achieve side radiation, then side irradiation capability is improved, but mechanical strength and fatigue resistance deteriorate

Engineering Contradiction:
Improveside irradiation capabilityVSAvoidbending strength
Core Design Contradiction:
Illumination intensityVSStrength

Solution Approach 1:

The patent applies local quality by creating scattering centers only in specific regions of the fiber core where side radiation is needed, while preserving the intact cladding structure throughout the fiber. This allows localized modification of optical properties without compromising the overall mechanical integrity of the fiber structure.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The patent replaces mechanical modification methods (micromachining, tapering, cladding removal) with optical modification using laser-induced scattering centers. This substitution eliminates mechanical damage to the fiber structure while achieving the desired side radiation effect through controlled optical property changes in the core material.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

2Illumination intensity

If conventional side scattering techniques are applied, then side irradiation is achieved, but reliability deteriorates due to increased susceptibility to mechanical failure

Engineering Contradiction:
Improveside scattering capabilityVSAvoidmechanical failure susceptibility
Core Design Contradiction:
Illumination intensityVSReliability

Solution Approach 1:

The patent replaces mechanical modification methods that create surface flaws and stress concentration points with optical modification using laser-induced scattering centers. This substitution eliminates the root cause of reliability degradation while maintaining side radiation functionality.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the physical and chemical parameters of the core material through laser irradiation to create scattering centers, rather than mechanically altering the fiber structure. This parameter change approach modifies optical properties without introducing mechanical defects that would compromise reliability.

Inventive Principle:
Principle #35Parameter changes

3Illumination intensity

If standard scattering centers creation technique is used, then side radiation is introduced, but manufacturing reliability deteriorates

Engineering Contradiction:
Improveside radiation effectVSAvoidmanufacturing reliability
Core Design Contradiction:
Illumination intensityVSEase of manufacture

Solution Approach 1:

The patent replaces complex mechanical micromachining processes with laser-based scattering center creation. This substitution simplifies the manufacturing process by using optical fields instead of mechanical tools, reducing the risk of manufacturing defects and improving process reliability.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 optical fiber exhibits improved bending strength and resistance to fatigue, while maintaining efficient side irradiation and enabling simultaneous stress/temperature sensing, with a bend strength of at least 0.5 GPa and uniform longitudinal power distribution.

Implementation Method 1

the core section is provided with a plurality of scattering sites, which are each formed by a local variation of the refractive index in the core section

Methodology Applied
Scientific EffectScattering: Scattering

Implementation Method 2

the outer cladding section and the core section forming an optical light guide

Methodology Applied
Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentEP4390218B1Strong, fatigue-resistant optical fiber with enhanced side irradiation
Publication Date: 2026.04.08 BIOLITEC HLDG GMBH & CO KG
  • EP4390218B1 patent drawingFigure 1~2
  • EP4390218B1 patent drawingFigure 3a~3b
  • EP4390218B1 patent drawingFigure 3c~3d

AI summary

An optical fiber is proposed comprising: an outer cladding section surrounding an inner core section, the outer cladding section having a refractive index lower than the refractive index of the core section and the outer cladding section and the core section forming an optical light guide; an emission area associated with one emission end of the optical fiber, the emission area extending in a longitudinal direction along the optical fiber and being arranged for emitting radiation in a lateral direction with respect to the longitudinal direction of the optical fiber; wherein within the emission area, the core section is provided with a plurality of scattering sites, which are each formed by a local variation of the refractive index in the core section.