Optical Fiber Design for Low Bending Loss
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Solution Overview
Problem
Optical fibers with thin coating resin thickness suffer from increased microbending loss when densely housed in cables due to irregular stress, leading to transmission loss issues.
Innovation Solution
The optical fiber design includes a glass fiber with a core, inner cladding, trench, and outer cladding, where the refractive indices are strategically layered to reduce the outer diameter while maintaining a sufficient coating resin thickness, using a cured ultraviolet curing resin composition for the coating, and incorporating germanium in the core and deuterium processing for the cladding to minimize microbending loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the coating resin thickness is reduced to decrease the optical fiber diameter, then the outer diameter of the optical fiber is reduced, but the coating resin becomes more susceptible to lateral pressure and irregular stress, causing increased microbending loss and transmission loss
Solution Approach 1:
The patent changes the physical and chemical parameters of the coating resin by using a dual-layer structure with specific resin compositions. The primary coating resin has lower viscosity and the secondary coating resin has higher viscosity, creating a gradient structure that maintains mechanical protection while reducing overall diameter. This parameter optimization allows the coating to resist lateral pressure effectively even at reduced thickness
Solution Approach 2:
The patent employs composite materials by combining two different resin compositions in a layered structure. The primary coating resin (lower viscosity) provides immediate protection and stress distribution, while the secondary coating resin (higher viscosity) provides enhanced mechanical strength and resistance to lateral pressure. This composite approach allows the optical fiber to maintain reliability with reduced overall coating thickness
2Volume of moving object
If the coating resin thickness is reduced to decrease the optical fiber diameter, then the outer diameter of the optical fiber is reduced, but irregular stress is more easily transmitted to the optical fiber core, causing irregular bending and increased transmission loss
Solution Approach 1:
The patent applies beforehand cushioning by creating a dual-layer coating structure that absorbs and distributes lateral pressure before it reaches the glass fiber core. The primary coating resin layer (applied first, lower viscosity) and secondary coating resin layer (applied second, higher viscosity) work together to cushion irregular stress, preventing direct transmission to the core and reducing microbending loss
Solution Approach 2:
The patent optimizes the viscosity parameters of the coating resins to create an ideal stress-distribution structure. The primary coating resin has lower viscosity (0.1-10 Pa·s) for better flow and stress distribution, while the secondary coating resin has higher viscosity (10-1000 Pa·s) for mechanical strength. This parameter optimization creates a gradient that cushions irregular stress effectively
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 transmission loss while reducing the fiber diameter, maintaining low bending loss and microbending loss, even under lateral pressure, and supports low-loss transmission of light across various wavelengths without the need for transmitter-receiver upgrades.
Implementation Method 1
The coating resin includes a cured material of an ultraviolet curing resin composition
Data Source
AI summary
An optical fiber includes a glass fiber and a coating resin covering an outer periphery of the glass fiber. The glass fiber includes a core, an inner cladding, a trench, and an outer cladding. An outer diameter of the glass fiber is 99 μm or larger and 101 μm or smaller. An outer diameter of the coating resin is 160 μm or larger and 170 μm or smaller. A mode field diameter for light having a wavelength of 1310 nm is 7.2 μm or larger and 8.2 μm or smaller. Bending loss at a wavelength of 1550 nm when wound in a ring shape having a radius of 10 mm is 0.1 dB/turn or less. Bending loss at the wavelength of 1550 nm when wound in the ring shape having the radius of 7.5 mm is 0.5 dB/turn or less.