Multi-core Fiber Marker Rod Design for Crosstalk Reduction
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Solution Overview
Problem
The conventional Rod-in-Cylinder method for manufacturing multi-core optical fibers restricts the size of the marker hole, leading to drilling accuracy and depth limitations, which compromises the strength of the hollow handle and limits the size and length of the multi-core fiber glass preform.
Innovation Solution
The method involves manufacturing a multi-core fiber with a marker drill hole diameter equal to the core drill hole diameter, increasing the D/d ratio of the marker rod to reduce crosstalk, and inserting the marker rod before attaching the handle, allowing for partial closure during welding, while using the same material for the marker and optical fiber preform and doping with up-dopants, down-dopants, or color dopants.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the marker hole size is increased to improve drilling accuracy and depth, then the marker identification capability is improved, but the thickness of the hollow handle decreases, compromising the strength of the hollow handle
Solution Approach 1:
The marker rod is inserted into the marker hole before the hollow handle is attached and welded. This preliminary action allows the marker rod to serve as a support structure during the welding process, enabling the hollow handle thickness to be reduced without compromising overall structural strength, as the marker rod provides internal reinforcement
Solution Approach 2:
The marker rod is nested within the hollow handle structure, with the marker rod positioned inside the marker hole that passes through the hollow handle. This nested configuration allows the marker rod to provide internal support while being contained within the handle structure, effectively reinforcing the handle without increasing external dimensions
2Ease of manufacture
If the marker hole size is increased to reduce drilling restrictions on depth and accuracy, then the manufacturing flexibility is improved, but the weight the hollow handle can support decreases
Solution Approach 1:
The marker rod is inserted before handle attachment and welding, serving as a preliminary structural element that provides internal support. This allows the hollow handle to be thinner with larger marker holes while still maintaining adequate load bearing capacity through the combined structure of handle plus embedded marker rod
3Measurement precision
If the marker drill hole diameter is increased to improve identification, then the marker visibility is improved, but the D/d ratio of the marker decreases, increasing crosstalk between the MCF core and the MCF marker
Solution Approach 1:
The D/d ratio parameter is specifically optimized for the marker rod, with the marker cladding diameter D being 1.5 to 3 times the marker core diameter d. This parameter optimization allows larger marker hole diameters for better identification while maintaining sufficient D/d ratio to control crosstalk through proper optical confinement
Solution Approach 2:
Different D/d ratios are applied to different components: the marker rod has a higher D/d ratio (1.5-3 times) compared to the core rods (D/d ratio of 1.15-1.5 times). This local differentiation allows the marker to have larger diameter for better visibility while maintaining appropriate optical isolation, as the higher D/d ratio provides better field confinement
4Manufacturing precision
If the marker rod is inserted before handle attachment, then the marker positioning accuracy is improved, but the manufacturing process complexity increases
Solution Approach 1:
The marker rod is inserted into the marker hole before the hollow handle is attached and welded. This preliminary positioning ensures accurate marker placement, and the subsequent welding process permanently secures the marker rod in the correct position, integrating it into the final structure without requiring additional complex positioning mechanisms
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
This approach enhances the identification of individual cores, reduces crosstalk, and maintains the structural integrity of the multi-core fiber glass preform, enabling increased size and length without compromising strength.
Implementation Method 1
The marker is doped with at least one of: up-dopant, down-dopant, colour dopant
Implementation Method 2
collapsing the preform assembly after the marker rod and the plurality of core rods are inserted
Implementation Method 3
The MCF glass preform is drawn to manufacture the multi-core fiber
Implementation Method 4
joining, after inserting the marker rod, a top hollow handle at a top end of the glass preform such that a handle thickness at least partially covers the marker hole
Data Source
AI summary
The present disclosure provides a multi-core fiber (MCF) and manufacturing method thereof and an MCF marker (or marker). The MCF (100) comprises a plurality of cores (102) and a marker (108). Each core is associated with a core diameter (104) and a core-placement-radius (106) and the marker (108) is associated with a marker diameter (110) and a marker-placement-radius (112). The marker has a marker core (116) and a marker clad (118) with a D/d ratio between 5 to 20. During manufacturing, the MCF is drawn from a preform assembly (200) having a top hollow handle (202) with a handle thickness (114) attached on a top end of a glass preform (204) that has a plurality of core holes (206) and a marker hole (210), wherein the marker hole (210) is at least partially covered by the top hollow handle of the handle thickness (114).