Colored Optical Fiber Coating Thermal Expansion Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Colored optical fibers experience increased transmission loss due to external stress and microbending, especially when exposed to varying temperatures and water immersion, with existing solutions failing to adequately address these issues and ensure long-term reliability.
Innovation Solution
A method for evaluating colored optical fibers by measuring the difference in thermal expansion between the optical fiber and its coating layers within a temperature range of -100°C to 100°C, using UV curing resin and controlling the glass transition temperatures and layer thicknesses to maintain a difference of 1.8 µm or less, thereby reducing delamination and transmission loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a two-layer coating structure with UV curing resin is used to protect the optical fiber, then the fiber strength is improved and adhesion is enhanced, but transmission loss increases when exposed to varying temperatures and water immersion
Solution Approach 1:
The invention changes the chemical composition parameters of the UV curing resin, specifically using a resin containing 70-90 mass% of a polyfunctional monomer with 3 or more functional groups and a glass transition temperature of -50°C or lower. This parameter change resolves the contradiction by maintaining strong adhesion and fiber strength while reducing thermal expansion differences that cause transmission loss in water-immersed conditions
Solution Approach 2:
The invention uses a composite resin system combining polyfunctional monomers with specific properties (3 or more functional groups, low glass transition temperature) in a specific ratio (70-90 mass%). This composite material approach allows the coating to simultaneously achieve strong adhesion to the glass fiber and minimal thermal expansion, preventing transmission loss increase in water-immersed environments
2Strength
If the coating resin has high adhesion to the glass optical fiber, then the fiber is well protected, but the transmission loss increases when immersed in water for long periods
Solution Approach 1:
The invention changes the glass transition temperature parameter of the coating resin to -50°C or lower and adjusts the functional group content to 70-90 mass% of polyfunctional monomers. This creates a coating that remains flexible and adherent in water while matching the thermal expansion characteristics of the glass fiber, preventing delamination and transmission loss increase
Solution Approach 2:
The invention applies local quality by creating a coating layer with specific chemical composition (high content of low-Tg polyfunctional monomer) that provides different properties than conventional coatings: high adhesion through chemical bonding to glass while simultaneously having low thermal expansion to match the glass fiber, thus preventing water-induced delamination
3Productivity
If conventional UV curing resin is used for coating, then the manufacturing process is simple and fast, but the colored optical fiber shows significant transmission loss increase in water-immersed conditions
Solution Approach 1:
The invention modifies the resin composition parameters to use 70-90 mass% polyfunctional monomer with 3 or more functional groups and glass transition temperature of -50°C or lower. This maintains the UV curing process efficiency while fundamentally improving water resistance by reducing thermal expansion mismatch between coating and glass fiber
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 approach effectively suppresses the increase in transmission loss and enhances water resistance, ensuring the colored optical fibers maintain low transmission loss even when immersed in water for extended periods.
Implementation Method 1
UV curing resin is mainly used as coating resin for an optical fiber... irradiating this optical fiber with UV rays, causing the UV curing resin to cure
Implementation Method 2
measuring an amount of thermal expansion of an optical fiber and a coating layer obtained by removing the glass optical fiber from the optical fiber in an outer diameter direction within a temperature range from -100°C to 100°C
Data Source
Figure 1~3
AI summary
A colored optical fiber whose transmission loss hardly increases even in a high humidity condition or water-immersed condition is provided. The colored optical fiber according to the present invention is a colored optical fiber having a colored coating layer on a circumference of an optical fiber having at least two coating layers on a circumference of a glass optical fiber, characterized in that a difference in each amount of thermal expansion in an outer diameter direction between the optical fiber and a coating layer obtained by removing the glass optical fiber from the optical fiber in a temperature range from -100°C to 100°C is 1.8 µm or less.