Multi-core optical fiber design for low bending loss and cross-talk
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Solution Overview
Problem
Current multi-core optical fibers face challenges in achieving high productivity while maintaining desired optical characteristics, such as low bending loss and cross-talk, due to the need for precise pressure control during manufacturing.
Innovation Solution
A multi-core optical fiber design with core diameters ≤12 micrometers, relative refractive-index differences ≥0.2%, cut-off wavelengths ≤1.53 micrometers, and optimized interval distances between core portions to minimize bending loss and cross-talk, allowing for high productivity without precise pressure control.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If hole-structure optical fiber with large number of holes is used to realize strong confinement of light, then core portions can be disposed with high density, but manufacturing precision becomes difficult to control
Solution Approach 1:
The patent changes the structural parameters by using a cladding portion with a specific refractive index (lower than core portions) and controlling core diameter (≤12 μm) and relative refractive-index difference (≥0.2%), which allows achieving the desired optical characteristics without requiring precise pressure control during manufacturing
Solution Approach 2:
The patent creates different local properties by having core portions with higher refractive index than the cladding portion, enabling strong light confinement and high core density without complex manufacturing pressure control
2Adaptability or versatility
If cut-off wavelength is shortened to enlarge transmission capacity, then single-mode transmission bandwidth increases, but bending loss increases
Solution Approach 1:
The patent optimizes the parameters of core diameter (≤12 μm) and relative refractive-index difference (≥0.2%) to achieve a cut-off wavelength of ≤1.53 μm while maintaining bending loss ≤10 dB/m at 1.55 μm, thus resolving the contradiction between transmission bandwidth and bending loss
Solution Approach 2:
The patent creates a dynamic balance by optimizing the refractive index distribution and geometric parameters to simultaneously satisfy multiple optical performance requirements across different wavelength bands
3Quantity of substance
If interval distance between core portions is reduced to increase core density, then cross-section area decreases, but cross-talk between core portions increases
Solution Approach 1:
The patent optimizes the interval distance between core portions by controlling core diameter (≤12 μm) and refractive index difference (≥0.2%), achieving sufficient core density while maintaining cross-talk ≤-35 dB at 1.55 μm
Solution Approach 2:
The cladding portion acts as an intermediary with lower refractive index that isolates the core portions, enabling high core density while suppressing cross-talk between adjacent cores
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 low bending loss (<10 dB/m) and cross-talk (<−35 decibels) across a large wavelength bandwidth, enabling high-capacity optical transmission with improved manufacturing efficiency.
Implementation Method 1
a cladding portion (3) that is positioned so as to surround outside of the core portions (1, 2) and has a refractive index that is lower than a refractive index of each of the core portions (1, 2)
Data Source
AI summary
A multi-core optical fiber includes a plurality of core portions. The diameter of each of the core portions is 12 micrometers or smaller, the relative refractive-index difference of the core portions with respect to the cladding portion is 0.2% or larger, the cut-off wavelength is 1.53 micrometers or smaller, the bending loss at a 1.55-micrometer wavelength is 10 dB/m or smaller, the effective core area at a 1.55-micrometer wavelength is 30μm2 or larger, and the cross-talk of light between the core portions is −35 decibels or smaller.