Multi-Clad Signal Fiber Structure to Prevent Core Deformation

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Solution Overview

Problem

The deformation of the signal fiber core during the tapering process in pump-signal combiners leads to signal degradation due to the lower softening temperature of the core material compared to the cladding layer, which is exacerbated by the compression from surrounding pump fibers.

Innovation Solution

Employing a multi-clad signal fiber with a second cladding layer made from a material with a lower softening temperature than the first cladding layer, which absorbs deformation during the tapering process, preserving the circular profile of the core and reducing signal loss.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a single-clad signal fiber is used in pump-signal combiner, then the device complexity is reduced, but the core deformation during tapering causes signal degradation

Engineering Contradiction:

Improvesignal fiber structureVSAvoidsignal quality

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The signal fiber is segmented into multiple functional cladding layers: a first cladding layer with higher softening temperature that maintains structural integrity, and a second cladding layer with lower softening temperature that absorbs deformation stresses. This segmentation allows each layer to perform its specific function, preventing core deformation while maintaining overall fiber functionality.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The second cladding layer acts as a pre-positioned cushioning layer that absorbs deformation stresses before they can reach and deform the core. By placing this protective layer beforehand, the core is shielded from the harmful effects of tapering-induced compression, preventing signal degradation.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

2Ease of manufacture

If the core material has lower softening temperature, then the manufacturing process is easier, but the core deforms under compression from pump fibers during tapering

Engineering Contradiction:

Improvetapering processVSAvoidcore circular profile

Core Design Contradiction:

Ease of manufactureVSShape

Solution Approach 1:

Different cladding layers are assigned different material properties (softening temperatures) based on their local functional requirements. The first cladding layer uses higher softening temperature material to maintain structural rigidity, while the second cladding layer uses lower softening temperature material to provide deformation absorption, creating localized quality variations that solve the overall problem.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The second cladding layer serves as an intermediary between the pump fibers and the core. It mediates the interaction by absorbing compression stresses before they reach the core, allowing the core to maintain its circular profile even during the tapering process with pump fibers surrounding it.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Adaptability or versatility

If pump fibers surround the signal fiber during tapering, then the pump-signal combining function is achieved, but the compression from pump fibers deforms the signal fiber core

Engineering Contradiction:

Improvepump-signal combining capabilityVSAvoidcore dimensional stability

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The second cladding layer is positioned beforehand to cushion the core against compression from surrounding pump fibers during the tapering process. This pre-positioned protective layer absorbs the mechanical stresses, allowing the pump-signal combining function to be achieved without compromising core dimensional stability.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

Solution Approach 2:

The signal fiber employs a composite structure with multiple cladding layers made from different materials with different softening temperatures. This composite design allows the fiber to simultaneously achieve pump-signal combining functionality and maintain core dimensional stability under compression during tapering.

Inventive Principle:

Principle #40Composite materials

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 multi-clad signal fiber design minimizes core deformation, maintaining signal brightness and reducing degradation of both signal and pump light by absorbing deformation stresses, thereby enhancing the performance of pump-signal combiners.

Implementation Method 1

a second cladding layer, surrounding the first cladding layer... made from a material with a lower softening temperature than the first cladding layer, which absorbs deformation during the tapering process

Methodology Applied

Scientific EffectDeformation absorption: Deformation

Implementation Method 2

a first cladding layer, surrounding the core, configured to confine the signal light within the core

Methodology Applied

Scientific EffectTotal internal reflection: Total Internal Reflection

Data Source

PatentUS20250323469A1Multi-clad signal fiber for pump-signal combiner

Publication Date: 2025.10.16 WELLS FARGO BANK NA

AI summary

In some implementations, a pump-signal fiber comprises a plurality of pump fibers configured to carry pump light and a signal fiber, surrounded by the plurality of pump fibers. In some implementations, the signal fiber comprises a core configured to carry signal light, a first cladding layer, surrounding the core, configured to confine the signal light within the core, and a second cladding layer, surrounding the first cladding layer.