Multicore Fiber Low-Refractive Index Layer Crosstalk
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Solution Overview
Problem
Multicore fibers face increased cutoff wavelength and inter-core crosstalk issues due to core arrangement, particularly when a core is surrounded by three or more cores, hindering single-mode communication.
Innovation Solution
A multicore fiber design where the specific core has a low-refractive index layer with higher light confinement loss compared to surrounding cores, balancing light escape and confinement to suppress cutoff wavelength increase and reduce crosstalk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a core is surrounded by three or more cores in the multicore fiber, then the inter-core distance decreases and more cores can be packed, but the cutoff wavelength of the specific core increases and single-mode communication cannot be performed
Solution Approach 1:
The patent applies local quality by giving different refractive index characteristics to different regions. Specifically, the low-refractive index layer surrounding the specific core has a refractive index lower than both the cladding and the inner cladding layer, creating a localized refractive index well that suppresses the cutoff wavelength increase. This local modification allows the specific core to maintain single-mode communication capability while surrounded by multiple other cores.
2Volume of moving object
If the diameter of the multicore fiber decreases to reduce the number of fibers needed, then the inter-core distance decreases, but inter-core crosstalk occurs more easily
Solution Approach 1:
The patent introduces a low-refractive index layer as an intermediary between the specific core and the surrounding cores. This layer acts as a mediator that reduces the electromagnetic field interaction between adjacent cores, thereby suppressing inter-core crosstalk. The low-refractive index layer serves as a buffer zone that prevents direct coupling between cores while allowing the fiber diameter to be reduced for compact deployment.
3Object-generated harmful factors
If a low-refractive index layer is formed around each core to reduce crosstalk, then inter-core crosstalk decreases, but the cutoff wavelength of the specific core increases due to the core arrangement
Solution Approach 1:
The patent applies parameter changes by precisely controlling the refractive index parameter of the low-refractive index layer. The key innovation is making the refractive index of this layer lower than both the cladding layer and the inner cladding layer, creating a refractive index gradient that simultaneously achieves crosstalk reduction and cutoff wavelength suppression. This parameter optimization resolves the contradiction between crosstalk reduction and cutoff wavelength control.
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 effectively suppresses the cutoff wavelength and inter-core crosstalk, enabling reliable single-mode communication by optimizing the refractive index distribution and structure of the low-refractive index layers.
Implementation Method 1
a low-refractive index layer having a lower refractive index than the cladding and the inner cladding layer and surrounding the inner cladding layer
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3A~3B
AI summary
Provided is a multicore fiber capable of suppressing a cutoff wavelength of a specific core from increasing while reducing inter-core crosstalk. A multicore fiber 100 includes a cladding (40) and a plurality of core elements 10b (23a) which is provided in the cladding 40 and includes a core 11 (21), an inner cladding layer 12 (22) that surrounds the core 11 (21), and a low-refractive index layer 13b (23a) that surrounds the inner cladding layer 12 (22) and has a lower average refractive index than the cladding (40) and the inner cladding layer 12 (22). The plurality of core elements 13b (23a) is arranged such that a specific core element 13b is surrounded by three or more core elements 23a, and a low-refractive index layer 13b of a partial core element 10b of the plurality of core elements 13b, 23a is configured to have larger light confinement loss in the core 11 than low-refractive index layers 23b of the other partial core elements 20a.