Multicore Fiber Design for Reduced Crosstalk and Microbend Loss
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Solution Overview
Problem
Multicore fibers with a 1-6-12 core arrangement face reliability issues due to close distances between the outer peripheral surface of the clad and the cores, leading to microbend loss and potential fracture when bent for laying, while increasing cladding diameter for more cores compromises reliability.
Innovation Solution
A multicore fiber design with a cladding diameter of 230 μm or less, arranging 7 to 12 cores at equal intervals, and using a trench-like low refractive index layer to reduce crosstalk and microbend loss, ensuring sufficient distance between cores and the clad to enhance reliability and information transmission capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the cladding diameter is increased to arrange more cores, then the number of cores increases, but the multicore fiber becomes easily fractured when bent and reliability decreases
Solution Approach 1:
The patent changes the cladding diameter parameter to 230 μm or less, which is larger than conventional 125 μm fibers but controlled to avoid excessive size. This parameter optimization allows arranging 7-12 cores while maintaining fracture resistance during laying operations.
Solution Approach 2:
The patent introduces a trench-like low refractive index layer between the cores and the outer clad surface. This creates a local protective zone that increases the distance between cores and the clad outer periphery, preventing microbend loss and improving reliability without requiring excessive cladding diameter.
2Quantity of substance
If the cladding diameter is increased to arrange more cores, then the number of cores increases, but microbend loss increases and reliability decreases
Solution Approach 1:
The trench-like low refractive index layer creates a local protective structure between the cores and the outer clad surface. This local modification increases the effective distance between cores and the clad outer periphery, reducing microbend loss caused by fiber bending during laying operations.
Solution Approach 2:
The low refractive index layer acts as an intermediary protective layer between the cores and the external environment. This intermediary structure reduces the direct impact of bending stresses on the cores, minimizing microbend loss while allowing the fiber to be laid with reasonable bend radii.
3Quantity of substance
If cores are arranged in a 1-6-12 arrangement to increase the number of cores, then the number of cores increases, but the distance between the outer peripheral surface of the clad and the cores becomes too close causing microbend loss
Solution Approach 1:
The patent introduces a trench-like low refractive index layer between the cores and the outer clad surface. This local protective zone increases the distance between cores and the clad outer periphery, preventing microbend loss and improving reliability without requiring excessive cladding diameter.
Solution Approach 2:
Instead of increasing the cladding diameter in the radial dimension to push cores outward, the patent adds a new dimensional layer (the trench-like low refractive index layer) between the cores and the outer clad. This dimensional approach effectively increases the protective distance without proportionally increasing the overall fiber size.
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 securely lays more cores with reduced microbend loss and crosstalk, maintaining reliability and increasing information transmission capacity beyond conventional multicore fibers.
Implementation Method 1
using a trench-like low refractive index layer to reduce crosstalk
Implementation Method 2
an optical fiber used for an optical fiber communication system which is generally spreading adopts a structure in which an outer periphery of a core is surrounded by a clad, and an optical signal propagates in this core
Data Source
AI summary
A multicore fiber for communication 10 which allows propagation of an optical signal includes: a clad 12; a core 11a which is arranged in a center of the clad 12; and seven to ten cores 11b which are arranged at equal intervals surrounding the core 11a, and the cladding diameter is 230 μm, distances between centers of the mutually neighboring cores 11a and 11b are 30 μm or more, distances between the centers of the cores 11b and an outer peripheral surface of the clad 12 are 35 μm or more and a mode field diameter of light propagating in the cores 11a and 11b is 9 μm to 13 μm.