Optical Fiber Two-Layer Coating Micro-Bend Resistance
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Solution Overview
Problem
Optical fibers face increased transmission loss due to external stress and micro-bends, and existing coatings do not adequately prevent void generation when immersed in water and dried, while also lacking solvent resistance.
Innovation Solution
An optical fiber with a two-layer coating system where the first coating layer has a Young's modulus of 0.55 MPa or less and a water extractable rate within a specific range (E≦8.61×PY+1.40) to prevent void formation, and a second coating layer with a higher Young's modulus for mechanical strength, using ultraviolet curable resin with adjusted molecular weights and monomer ratios to achieve these properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Young's modulus of the first coating layer is reduced to improve micro-bend resistant property, then micro-bend resistance is improved, but void generation occurs when immersed in water and dried, increasing transmission loss
Solution Approach 1:
The patent applies parameter changes by precisely controlling the water extractable rate of the first coating layer within the range of 1.0 mass·% to 5.0 mass·%. This parameter control allows the coating to have sufficient flexibility for micro-bend resistance while preventing excessive water extraction that causes void formation during drying, thus resolving the contradiction between micro-bend resistance and void generation.
Solution Approach 2:
The patent uses composite materials by combining the first coating layer with controlled water extractability and the second coating layer with higher mechanical strength. This composite structure allows the first layer to provide micro-bend resistance while the second layer prevents void generation and maintains structural integrity after water immersion and drying.
2Object-affected harmful factors
If the first coating layer has low Young's modulus to reduce external stress impact, then micro-bend resistance is improved, but transmission loss increases due to void formation after water immersion
Solution Approach 1:
The patent resolves this contradiction by changing the water extractable rate parameter of the first coating layer to a specific range (1.0-5.0 mass·%). This prevents excessive water extraction during drying that would create voids and increase transmission loss, while still maintaining low enough Young's modulus to protect against external stress.
Solution Approach 2:
The second coating layer acts as an intermediary that protects the first coating layer from void formation issues. While the first layer provides stress relief, the second layer prevents water extraction-induced voids and maintains structural integrity, thus preventing transmission loss increase.
3Ease of manufacture
If conventional coating resin is used to provide basic protection, then coating is formed, but solvent resistance is insufficient when exposed to ethanol for long hours
Solution Approach 1:
The patent applies parameter changes by selecting coating resin with specific water extractable rate characteristics (1.0-5.0 mass·%). This parameter selection provides both ease of coating formation and superior solvent resistance, as the controlled water extractability prevents excessive swelling and degradation when exposed to solvents like ethanol.
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 effectively reduces transmission loss, prevents void generation, and enhances solvent resistance and micro-bend resistance, ensuring the optical fiber performs well under immersion and drying conditions.
Implementation Method 1
it is effective to reduce the Young's modulus of the first coating layer... a first coating layer 31... Young's modulus of the first coating layer provided on the nearest side of the glass optical fiber out of the at least two coating layers is defined by PY (MPa)
Implementation Method 2
a water extractable rate of the coating resin after the optical fiber has been immersed in hot water of 60° C. for 168 hours is defined by E (mass·%)
Data Source
AI summary
The present invention provides an optical fiber in which transmission loss is not easily increased when the optical fiber is dipped in water and then dried and also which has a solvent resistant property and a micro-bend resistant property. An optical fiber according to one embodiment of the present invention is an optical fiber in which at least two layers of coating resin coat the circumference of a glass optical fiber. When a Yang's modulus of the first coating layer of the coating resin is defined by PY (MPa) and an elution rate of the coating resin after dipping in 60° C. hot water for 168 hours is defined by E (mass·%), a formula of 1.8≦E≦8.61×PY+1.40 is satisfied.