Duplex Cable Design for Bend-Insensitive Fiber Reliability
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Solution Overview
Problem
Conventional multimode fiber optic cables in data centers face issues with performance, manageability, bend tolerance, handleability, and flexibility due to their large core size, which leads to increased cooling costs and attenuation losses, especially when cables are intertwined or in zipcord configurations.
Innovation Solution
A duplex cable design featuring a polymer jacket with a pair of optical waveguides and a strain-relief component, including tensile yarns that allow fibers to move within the cable, reducing bending stresses and maintaining low delta attenuation even when wrapped around a mandrel, along with the option to form breakout or zipcord cables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional duplex cables with fibers disposed in a cavity are used, then data capacity is achieved, but the fibers become intertwined causing attenuation losses
Solution Approach 1:
The cable is divided into two separate legs, each containing one fiber, rather than placing both fibers in a shared cavity. This segmentation prevents the fibers from intertwining and causing attenuation losses while maintaining data capacity through the separate transmission paths.
2Reliability
If zipcord cables with one fiber in each leg are used, then fiber intertwining is prevented, but the cable cross-section becomes relatively large
Solution Approach 1:
Each fiber is nested within its own protective leg structure, with the fiber positioned centrally within the leg. This nested configuration maximizes the use of space within each leg while preventing fiber intertwining, achieving a compact cable design that prevents attenuation losses without excessive cross-sectional area.
3Area of stationary object
If ribbonized fibers are used, then cable compactness is improved, but the fibers become difficult to separate for connectorization
Solution Approach 1:
The cable is segmented into two distinct legs with one fiber each, rather than binding multiple fibers together in a ribbon. This segmentation maintains cable compactness while ensuring that each fiber remains individually accessible and easy to separate for connectorization, as each fiber is already isolated in its own leg.
4Productivity
If multimode optical fibers with large core are used, then data capacity is achieved, but cooling costs increase due to large cable volume
Solution Approach 1:
The cable is segmented into two thin legs rather than a single large cable, reducing the overall cable volume and improving air flow in data centers. This segmentation maintains data capacity through the two separate multimode fibers while reducing cooling costs by minimizing the space occupied by cable infrastructure.
5Ease of operation
If cables are wrapped around small mandrels for installation, then installation flexibility is improved, but delta attenuation increases
Solution Approach 1:
The cable design incorporates dynamic flexibility through its leg structure, allowing the cable to bend and wrap around small mandrels during installation. The separate legs can flex independently, providing installation flexibility while the fiber positioning within each leg maintains optical signal quality even when wrapped around 5.8 mm mandrels.
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 solution provides improved bend resistance and reduced attenuation, enabling aggressive bending and higher density installations while maintaining optical performance, thus reducing cooling costs and enhancing installation flexibility.
Implementation Method 1
The strain-relief component may include a plurality of tensile yarns that allow the fibers to move about within the interior of the cable jacket so as to reduce bending stresses on the fibers
Implementation Method 2
a pair of optical waveguides in the jacket... The cable may have low delta attenuation, so that when the cable is wrapped around a 5.8 mm mandrel four times, delta attenuation due to the wraps is less than 1.0 db at 1300 nm and at 850 nm
Data Source
AI summary
Interconnect cables utilize bend-insensitive fibers and relatively large free space areas in the cable jackets to reduce bend-induced delta attenuation. Tensile yarns can be included as strain-relief components, but can be relatively loosely packed in order to inhibit bend-induced attenuation.