Fiber Retaining Unit Flexure Joint Thermal Stability

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Solution Overview

Problem

Fiber laser amplifier systems face challenges with thermal susceptibility and instability due to non-linear effects in short-pulse and ultra-short-pulse systems, and high accuracy is required for optical component positioning, which is difficult to maintain under thermal stress.

Innovation Solution

A fiber holding unit with a flexure joint configuration that decouples thermal deformations, allowing for stable fiber positioning and heat dissipation through materials like copper or aluminum, and using absorber sleeves to manage pump light divergence, ensuring minimal mechanical stress and optimal fiber alignment.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If passive transport fibers are used to feed and remove signal and pump radiation, then the fiber amplifier unit can operate continuously or with long laser pulses, but non-linear effects occur in short-pulse and ultra-short-pulse systems due to high intensities in the fiber core

Engineering Contradiction:
Improvelaser pulse durationVSAvoidnon-linear effects
Core Design Contradiction:
Duration of action of moving objectVSObject-affected harmful factors

Solution Approach 1:

The patent extracts the fiber from the passive transport fiber configuration and implements free beam coupling instead. This removes the fiber core from the high-intensity short-pulse environment, eliminating the source of non-linear effects while enabling short-pulse and ultra-short-pulse operation.

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent replaces the mechanical fiber coupling system with a free beam optical coupling system. This substitution eliminates the mechanical constraints and non-linear effects associated with fiber-based transport, allowing direct beam coupling between optical components.

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

2Object-affected harmful factors

If free beam coupling is used to avoid non-linear effects, then short-pulse and ultra-short-pulse operation becomes possible, but the highest level of accuracy and stability is required for positioning optical components

Engineering Contradiction:
Improvenon-linear effectsVSAvoidoptical component positioning accuracy
Core Design Contradiction:
Object-affected harmful factorsVSManufacturing precision

Solution Approach 1:

The patent segments the fiber holder unit into multiple parts connected by flexure joints. This segmentation allows each component to move independently to compensate for thermal expansion, maintaining positioning accuracy without requiring ultra-precise manufacturing tolerances for the entire assembly.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The patent uses flexure joints that change their mechanical parameters (flexibility, range of motion) in response to temperature changes. This allows the system to adapt to thermal expansion dynamically rather than requiring fixed precision, reducing manufacturing complexity.

Inventive Principle:
Principle #35Parameter changes

3Reliability

If optical components are positioned with high accuracy for free beam coupling, then coupling performance is improved, but thermal stress causes expansion and position changes that lead to deterioration and instability

Engineering Contradiction:
Improvecoupling stabilityVSAvoidthermal stress
Core Design Contradiction:
ReliabilityVSTemperature

Solution Approach 1:

The patent explicitly designs the fiber holder unit to accommodate thermal expansion through flexure joints. These joints allow controlled movement and expansion of components in response to temperature changes, preventing the deterioration and instability that would otherwise occur from thermal stress.

Inventive Principle:
Principle #37Thermal expansion

Solution Approach 2:

The patent transitions from a static, rigid positioning system to a dynamic system with flexure joints that can adapt and move in response to thermal conditions. This dynamic capability maintains coupling stability despite temperature fluctuations during operation and transport.

Inventive Principle:
Principle #15Dynamics

4Manufacturing precision

If the fiber holder unit is made rigid to maintain positioning accuracy, then coupling precision is improved, but thermal susceptibility increases leading to expansion and position changes

Engineering Contradiction:
Improvefiber positioning accuracyVSAvoidthermal susceptibility
Core Design Contradiction:
Manufacturing precisionVSStability of the object's composition

Solution Approach 1:

The patent employs flexure joints that function as flexible mechanical elements within the holder unit. These flexible connections allow the rigid positioning components to maintain accuracy while the flexible joints absorb thermal expansion and contraction, reducing overall thermal susceptibility.

Inventive Principle:
Principle #30Flexible shells and thin films

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 provides enhanced stability and reduced non-linear effects, maintaining pulse quality and improving the overall performance of fiber laser amplifier systems by minimizing thermal expansion impacts and ensuring accurate coupling.

Implementation Method 1

there can be expansion or changes in position within the fiber laser configuration

Methodology Applied
Scientific EffectThermal expansion: Thermal Expansion

Implementation Method 2

heat dissipation through materials like copper or aluminum

Methodology Applied
Scientific EffectThermal conduction: Conduction (thermal)

Implementation Method 3

using absorber sleeves to manage pump light divergence

Methodology Applied
Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentEP3365714B1Fiber-retaining unit and fiber-holding element
Publication Date: 2021.05.26 TRUMPF LASER GMBH CO KG
  • EP3365714B1 patent drawingFigure 1~2
  • EP3365714B1 patent drawingFigure 3~4
  • EP3365714B1 patent drawingFigure 5~8

AI summary

The invention relates to a fiber-retaining unit (1) for providing an optical fiber (19) for a fiber laser system comprising a main body (1A). Said main body has a fiber-end fastening section (31A, 31B), a fiber-guiding section (33), and a connection section (35A, 35B) between the fiber-end fastening section (31A, 31B) and the fiber-guiding section (33). The fiber-end fastening section (31A, 31B) is designed to fasten a holding element (13) that retains a fiber end region (19A) of the optical fiber (19), the fiber-guiding section (33) is designed to guide a fiber center region of the optical fiber (19), and the connection section (35A, 35B) is designed as a solid-body joint between the fiber-end fastening section (31A, 31B) and the fiber-guiding section (33).