Amplifying Fiber Segmentation for Bend Distortion Mitigation

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Solution Overview

Problem

Conventional optical amplification fiber assemblies prioritize packaging and bend-induced losses over mode distortion, leading to performance limitations in optical devices due to bend distortion, especially in high-power applications where modefield distortion and nonlinearity become significant.

Innovation Solution

The method involves selectively unbending critical portions of the amplification fiber to mitigate modefield distortion while maintaining a compact package size by coiling less susceptible portions, thereby optimizing the refractive index profile and curvature to reduce nonlinear impairments and energy extraction issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Volume of moving object

If the amplification fiber is coiled to provide compact packaging, then the device size is reduced, but modefield distortion and nonlinear impairments increase

Engineering Contradiction:
Improvedevice sizeVSAvoidmodefield distortion
Core Design Contradiction:
Volume of moving objectVSManufacturing precision

Solution Approach 1:

The amplification fiber is divided into multiple sections with different curvature radii. A first section has a first curvature radius that causes less modefield distortion, while a second section has a second curvature radius that enables compact packaging. This segmentation allows different parts of the fiber to serve different functions: maintaining mode quality in critical sections while achieving compact overall device size through coiled sections.

Inventive Principle:
Principle #1Segmentation

2Volume of moving object

If the bend radius is reduced to achieve compact packaging, then the device size is reduced, but bend-induced losses and mode distortion increase

Engineering Contradiction:
Improvedevice sizeVSAvoidbend-induced losses
Core Design Contradiction:
Volume of moving objectVSLoss of energy

Solution Approach 1:

Different sections of the amplification fiber are assigned different local curvature properties. Sections where the fiber is subjected to bending are designed with specific curvature radii that balance compact packaging requirements against bend-induced losses and mode distortion. This local differentiation of curvature quality allows the fiber to maintain optimal performance in critical sections while achieving compact overall dimensions.

Inventive Principle:
Principle #3Local quality

3Reliability

If the amplification fiber is bent to remove unwanted modes, then mode filtering is improved, but signal light losses and modefield distortion increase

Engineering Contradiction:
Improvemode filteringVSAvoidsignal light losses
Core Design Contradiction:
ReliabilityVSLoss of energy

Solution Approach 1:

The fiber is segmented into sections with different curvature radii, where certain sections are optimized for mode filtering while others are optimized for signal transmission. By placing mode-filtering bends in specific locations and using appropriate curvature radii, the system can effectively remove unwanted modes while minimizing signal light losses and modefield distortion in other critical sections.

Inventive Principle:
Principle #1Segmentation

Data Source

PatentEP2031713B1Method and arrangement for mitigating bend distortion impact in a fiber amplifier or laser
Publication Date: 2019.09.04 OFS FITEL LLC
  • EP2031713B1 patent drawingFigure 1A~2B
  • EP2031713B1 patent drawingFigure 3
  • EP2031713B1 patent drawingFigure 4A

AI summary

A method of producing an optical amplifying assembly includes providing an amplifying fiber and selecting a first portion and a second portion of the amplifying fiber such that a bend of substantially the same radius and length would cause greater distortion impairments in the first portion than in second portion. The method further includes coiling the second portion and arranging the first portion to mitigate the impairments due to bend distortion.