Multicore Fiber Asymmetric Core Arrangement Crosstalk Reduction
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Solution Overview
Problem
Multicore fibers with rotationally symmetric core arrangements face challenges in suppressing crosstalk and facilitating connections due to concentrated crosstalk on the center core and difficulty in specifying desired cores without markers.
Innovation Solution
A multicore fiber design with 3 to 5 cores arranged at non-rotationally symmetric positions on the circumference, where no core is at the center, and angles between adjacent cores are all greater than 60°, reducing crosstalk and enabling easy core specification and connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a center core is arranged at the center of the cladding with outer cores arranged at equal intervals, then the core arrangement is simple and symmetric, but crosstalk concentrates on the center core
Solution Approach 1:
The patent applies asymmetry by removing the center core from the center position and arranging all cores on the circumference. The outer cores are positioned at non-equal angular intervals (e.g., 72°, 108°, 36° for five cores), creating an asymmetric arrangement that prevents crosstalk concentration while maintaining manufacturability.
2Shape
If outer cores are arranged at rotationally symmetric positions, then the arrangement is geometrically regular, but it becomes difficult to specify desired cores for connection
Solution Approach 1:
The patent uses asymmetric angular positioning of cores on the circumference (e.g., different angles between adjacent cores) to create unique identification patterns. This allows operators to easily specify and connect desired cores without requiring markers, while maintaining a regular circular arrangement that is easy to manufacture.
3Quantity of substance
If cores are arranged closer to the cladding center, then the core pitch can be reduced, but absorption by the cover layer and disturbance influence increase
Solution Approach 1:
The patent transitions from a traditional arrangement where cores are positioned radially at different distances from the center, to a configuration where all cores are positioned on the same circumferential ring. This dimensional reorganization allows optimized spacing between cores while maintaining adequate distance from the cladding boundary, reducing cover layer absorption and disturbance effects.
Data Source
AI summary
A multicore fiber includes: a cladding; and three or more and five or less cores disposed at rotationally asymmetric positions on a circumference centered at a center of the cladding. No core is disposed at the center of the cladding. Angles formed by adjacent ones of lines connecting the center of the cladding and respective ones of the cores are all larger than 60°.