Small Bending Radius Single-Mode Optical Fiber Design
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Solution Overview
Problem
Conventional single-mode optical fibers suffer from reduced bending resistance, leading to signal attenuation and heating issues when used in densely packed communication networks, necessitating the development of super-strong bending-resistant fibers compatible with G.652 fibers to maintain communication stability and reduce splicing losses.
Innovation Solution
A small bending radius single-mode optical fiber design featuring a core gradient layer, germanium-doped core layer, and multiple concentric wrapping layers with specific refractive index differences, optimized to enhance bending resistance and compatibility with conventional fibers through a mountain-shaped waveguide structure and transition layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If super-strong bending-resistant optical fibers with bending radius of 3mm or 2mm are used, then bending resistance is improved, but compatibility with conventional G.652 optical fibers deteriorates, causing high splicing loss
Solution Approach 1:
The patent applies local quality by creating a multi-layer structure where different regions have different refractive indices and material compositions. The core gradient layer has a specific refractive index profile, the germanium-doped core layer provides bending resistance, and the fluorine-doped cladding layer reduces stress. This localized differentiation of properties enables the fiber to achieve both super-strong bending resistance and compatibility with conventional G.652 fibers by carefully controlling the optical and mechanical characteristics in specific regions.
Solution Approach 2:
The patent employs composite materials by combining multiple doped layers with different material properties. The core gradient layer, germanium-doped core layer, and fluorine-doped cladding layer form a composite structure that integrates the advantages of each material. The germanium doping provides high refractive index for bending resistance, while fluorine doping creates a low refractive index cladding that reduces stress and improves compatibility. This composite approach enables simultaneous achievement of super-strong bending resistance and low splicing loss.
2Area of stationary object
If optical fibers are arranged in a small distributor with great number of fibers, then floor space requirement is met, but bending performance deteriorates due to narrowed space and increased bending
Solution Approach 1:
The patent applies parameter changes by modifying the refractive index profile and material composition parameters of the optical fiber. The core gradient layer with specific refractive index difference (Δn1), the germanium-doped core layer with controlled doping concentration, and the fluorine-doped cladding layer with specific refractive index difference (Δn2) are designed to change the optical and mechanical parameters of the fiber. These parameter changes enable the fiber to achieve super-strong bending resistance, allowing it to maintain high bending performance even when arranged in dense configurations with small bending radii in compact distributors.
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 design achieves strong bending resistance with minimal additional loss, ensuring compatibility and low attenuation, thereby supporting high-quality signal transmission and reducing heating in densely packed communication networks.
Implementation Method 1
a core gradient layer and a germanium-doped core layer arranged concentrically... when the operating wavelength is 1550nm, the attenuation of the small bending radius single-mode optical fiber is below 0.2dB/km
Implementation Method 2
a first wrapping layer, a second wrapping layer and a third wrapping layer arranged concentrically from the inner to the outer... the difference of relative index of refraction of the core gradient layer is Δn1... the difference of relative index of refraction of the second wrapping layer is from -1.3% to -0.3%
Data Source
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Figure 5
AI summary
Disclosed is a small bending radius single-mode optical fiber with compatibility, which relates to the field of single-mode optical fibers. The optical fiber comprises a core gradient layer, a germanium-doped core layer, a first transition layer, a first wrapping layer, a second transition layer, a second wrapping layer, a third transition layer and a third wrapping layer, said layers being arranged concentrically from the inner to the outer. The difference of relative index of refraction of the core gradient layer is Δn1, which is realized through an equation: Δn1 = a1(x1 + x12 + x13) + b1; the difference of relative index of refraction of the first transition layer is Δn3, which is realized through an equation: Δn3 = b3(1 - a3x32)0.5; the difference of relative index of refraction of the second transition layer is Δn5, which is realized through an equation: Δn5 = a5x52 + b5; the difference of relative index of refraction of the third transition layer is Δn7, which is realized through an equation: Δn7 = a7x72 + b7. The small bending radius single-mode optical fiber with compatibility achieves a quite strong resistance to bending, the radius of which is below 2mm, and is well compatible with conventional single-mode optical fibers.