Radial Halogen Profiling in Optical Fiber Cores for Lower Rayleigh Loss
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Solution Overview
Problem
Existing optical fibers suffer from increased transmission loss due to Rayleigh scattering caused by uneven halogen element concentrations, which affect the refractive index distribution and structural irregularities in the glass composition.
Innovation Solution
The optical fiber design includes a core and cladding made of silica-based glass with specific relative refractive index differences (Δ1, Δ2, Δ3, Δ4) that are optimized to minimize transmission loss by controlling halogen concentrations, particularly in the central region of the core, and maintaining a balanced refractive index profile across the radial distances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the concentration of doped halogen elements is decreased to reduce Rayleigh scattering, then transmission loss is reduced, but the refractive index adjustment capability is compromised
Solution Approach 1:
The patent applies local quality by creating different halogen concentration zones within the core region. The outer core region maintains higher halogen concentration for refractive index adjustment, while the inner core region has lower halogen concentration to reduce Rayleigh scattering. This spatial differentiation allows simultaneous optimization of both transmission loss and refractive index control.
Solution Approach 2:
The core is segmented into multiple radial regions with distinct halogen concentration characteristics. The patent defines a first core region (outer core) with higher halogen concentration and a second core region (inner core) with lower halogen concentration. This segmentation enables independent optimization of refractive index properties in the outer region and scattering properties in the inner region.
2Loss of energy
If halogen elements are removed to minimize Rayleigh scattering, then transmission loss is reduced, but structural irregularity increases
Solution Approach 1:
The patent changes the concentration parameter of halogen elements radially through the core. By controlling the halogen concentration to decrease from the outer core toward the inner core, the patent simultaneously achieves reduced Rayleigh scattering (lower transmission loss) and maintained structural regularity (reduced scattering due to structural irregularity).
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 optimized refractive index distribution reduces transmission loss to 0.1465 dB/km or less by minimizing Rayleigh scattering and structural irregularity, while maintaining effective area and bending loss resistance.
Implementation Method 1
The transmission loss value at a wavelength in a near-infrared region is composed of the sum of a plurality of scattering and absorption factors such as Rayleigh scattering, infrared absorption, OH absorption, and scattering due to structural irregularity.
Implementation Method 2
The transmission loss value at a wavelength in a near-infrared region is composed of the sum of a plurality of scattering and absorption factors such as Rayleigh scattering, infrared absorption, OH absorption
Data Source
AI summary
An optical fiber comprising: a core made of silica glass; and a cladding that is made of silica glass and that surrounds the core, wherein Δ1-Δ2≥0.02 is satisfied, where Δ1 represents the greatest value of the specific refractive index difference of the core in 0≤r/a≤0.3, and Δ2 represents the smallest value of the specific refractive index difference of the core in 0≤r/a≤0.9, where r represents the radial distance from the center axis of the core, and a represents the radius of the core.