Multicore Fiber Cable Crosstalk Mitigation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing optical fiber cables with multicore fibers experience increased crosstalk due to temperature changes, as the thermal expansion coefficients of the resin sheath and silica optical fibers differ, causing variations in bending radius that exacerbate crosstalk interference.
Innovation Solution
The optical fiber cable design includes a tubular sheath with multicore fibers where the bending radius of the multicore fibers is maintained outside the worst-case bending radius range (RPk) at both lowest and highest operating temperatures (RLo and RHi) to mitigate crosstalk, using a resin sheath and silica fibers with controlled thermal expansion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If a bending structure is additionally provided to a multicore fiber to decrease crosstalk, then crosstalk is reduced at a predetermined bending radius, but crosstalk becomes the worst depending on ambient temperature changes
Solution Approach 1:
The patent applies parameter changes by adjusting the bending radius of the multicore fiber to satisfy specific mathematical relationships (RLo ≤ RPk or RHi ≥ RPk) that ensure the bending radius remains outside the worst-case range across temperature variations. This resolves the contradiction by making the bending radius dynamically adapt to temperature changes while maintaining crosstalk suppression.
Solution Approach 2:
The patent implements preliminary action by pre-determining the bending radius requirements based on temperature-dependent analysis. The bending structure is designed in advance to ensure that at both lowest and highest operating temperatures, the bending radius satisfies the condition of being outside the worst-case range, preventing crosstalk deterioration before temperature changes occur.
2Ease of manufacture
If the sheath is made of resin with different thermal expansion coefficient than the optical fiber, then the cable is easy to manufacture and install, but the bending radius of the optical fiber changes with temperature causing increased crosstalk
Solution Approach 1:
The patent addresses this contradiction by changing the bending radius parameter dynamically in response to temperature changes. Although the sheath material (resin) maintains ease of manufacture, the bending radius is adjusted through design constraints (RLo ≤ RPk or RHi ≥ RPk) to compensate for thermal expansion differences and prevent crosstalk.
Solution Approach 2:
The patent converts the harmful effect of thermal expansion differences into a beneficial design constraint. The varying bending radius caused by thermal expansion is not merely tolerated but is systematically managed by ensuring the bending radius satisfies the condition of being outside the worst-case range, turning a potential harm into a controlled characteristic.
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 design effectively suppresses crosstalk across varying temperatures by ensuring the multicore fiber bending radius remains outside the worst-case scenario, maintaining optimal signal transmission even with ambient temperature changes.
Implementation Method 1
the thermal expansion coefficient of the sheath is different from the thermal expansion coefficient of the optical fiber. Therefore, the bending radius of the optical fiber disposed in the sheath is changed depending on the ambient temperature
Data Source
AI summary
An optical fiber cable includes a tubular sheath and a plurality of optical fibers disposed in the space of the sheath as the optical fibers are bent. In the plurality of optical fibers, at least one optical fiber is a multicore fiber. The multicore fiber satisfies an expression RPk<RLo, or RHi<RPk, where a bending radius at which the crosstalk of the multicore fiber becomes the worst is defined as RPk, a bending radius of the multicore fiber at a lowest temperature in operating temperature limits is defined as RLo, and a bending radius of the multicore fiber at a highest temperature in the operating temperature limits is defined as RHi.