Small-Diameter Optical Fiber Leakage Loss Reduction
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Solution Overview
Problem
Existing small-diameter optical fibers face challenges in reducing leakage loss while meeting the requirements of high-density optical fiber cables, particularly in achieving diameters smaller than 100 μm while satisfying standards like G.652, G.654, and G.657.
Innovation Solution
The optical fiber design includes a core and cladding made of silica-based glass with a specific refractive index profile, featuring a relative refractive-index difference of 0.32% to 0.40% between the core and cladding, and optionally a trench layer, which optimizes the fiber diameter and reduces leakage loss by optimizing the core and cladding dimensions and the trench position.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the cladding outer diameter is reduced to achieve high-density cable packing, then cable density improves, but leakage loss increases
Solution Approach 1:
The patent applies local quality by creating a trench layer with distinct refractive index characteristics at a specific position within the cladding, adjacent to the core. This localized structural modification allows the fiber to maintain small overall diameter while the trench region provides enhanced optical confinement to reduce leakage loss.
Solution Approach 2:
The patent utilizes parameter changes by optimizing the relative refractive-index difference (Δ) within the specific range of 0.32% to 0.40%, and by controlling the trench layer's refractive index and position. These parameter optimizations enable the fiber to achieve reduced leakage loss despite the reduced cladding diameter of less than 100 μm.
2Loss of energy
If the relative refractive-index difference is increased to reduce leakage loss, then optical confinement improves, but manufacturing precision requirements increase
Solution Approach 1:
The patent specifies an optimized range for the relative refractive-index difference (0.32% to 0.40%) that balances leakage loss reduction with manufacturability. This parameter optimization allows sufficient optical confinement while maintaining feasible manufacturing precision for dopant concentration control during fiber fabrication.
Solution Approach 2:
The patent segments the cladding structure into different regions with distinct refractive index characteristics, including a trench layer with lower refractive index adjacent to the core. This segmentation allows independent optimization of each region's properties, enabling leakage loss reduction through the trench structure while maintaining overall manufacturing feasibility.
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 achieves a small-diameter optical fiber with reduced leakage loss, meeting stringent standards such as G.652, G.654, and G.657, while minimizing material usage and cost, and maintaining stable optical properties.
Implementation Method 1
a cladding portion made of glass, having a refractive index lower than the refractive index of the core portion, and positioned on an outer periphery of the core portion
Data Source
AI summary
An optical fiber includes: a core portion made of glass; and a cladding portion made of glass, having a refractive index lower than the refractive index of the core portion, and positioned on an outer periphery of the core portion. Further, the cladding portion has an outer diameter smaller than 100 μm, and the core portion has a relative refractive-index difference of 0.32% to 0.40% with respect to the cladding portion.