Optical Fiber Coating Relaxation Modulus Delamination
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Solution Overview
Problem
Conventional optical fibers experience delamination between the glass optical fiber and the primary coating layer when immersed in water, leading to increased transmission loss due to microbending, with existing methods failing to effectively prevent this issue.
Innovation Solution
The optical fiber design features a secondary coating layer with a relaxation modulus of 400 MPa or less and the addition of 1.0 parts per hundred of silane coupling agent to the primary coating layer, reducing residual stress and enhancing adhesiveness, thereby preventing delamination and transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a hard secondary coating layer with high Young's modulus (500 MPa or more) is used, then the mechanical strength and protection are improved, but the residual stress increases causing delamination between the glass optical fiber and primary coating layer
Solution Approach 1:
The patent changes the mechanical parameter of the secondary coating layer from high Young's modulus (500 MPa or more) to controlled relaxation modulus (400 MPa or less). This parameter change allows the coating to better accommodate thermal and mechanical stresses, preventing delamination while maintaining protective functions.
Solution Approach 2:
The patent uses a composite coating structure with two distinct layers: a soft primary coating layer (Young's modulus 3 MPa or less) and a secondary coating layer with controlled relaxation modulus. This composite structure combines the advantages of both soft and relatively harder materials to achieve both protection and stress management.
2Stability of the object's composition
If the secondary coating layer has high rigidity, then the structural stability is improved, but the residual stress causes microbending and increased transmission loss
Solution Approach 1:
The patent modifies the rigidity parameter of the secondary coating layer by controlling its relaxation modulus to be 400 MPa or less. This adjustment reduces the rigidity enough to minimize stress-induced microbending while preserving sufficient structural stability for practical applications.
3Ease of manufacture
If conventional UV curable resins are used for coating layers, then the manufacturing process is simple, but delamination occurs when the optical fiber is immersed in water
Solution Approach 1:
The patent employs a composite coating system using UV curable resins with specific mechanical properties: a soft primary layer and a secondary layer with controlled relaxation modulus. This composite approach maintains the ease of UV curing manufacturing while achieving water resistance through optimized interlayer stress distribution.
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
This design effectively suppresses delamination and transmission loss even when immersed in water, ensuring high reliability and performance of the optical fiber as a transmission line.
Implementation Method 1
the addition of 1.0 parts per hundred of silane coupling agent to the primary coating layer, reducing residual stress and enhancing adhesiveness
Implementation Method 2
the relaxation modulus of the secondary coating layer is 400 MPa or less, the residual stress between the glass optical fiber and the primary coating layer at the time of manufacturing the optical fiber can be suppressed to a small level
Data Source
AI summary
An optical fiber is provided, which is unlikely to cause interlayer delamination between a glass optical fiber and a primary coating layer even when it is immersed in water. The optical fiber of the present invention includes a glass optical fiber 1 consisting of a core and a cladding, a primary coating layer 2 overlaid on the glass optical fiber, and a secondary coating layer 3 overlaid on the primary coating layer, wherein the relaxation modulus of the secondary coating layer is set at 400 MPa or less.