Fiber Optic Cable Expansion Joint for Microbending
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Solution Overview
Problem
Loose tube fiber optic cables experience increased insertion loss due to microbending when optical fibers are constrained, and existing solutions like annealing or leaving gaps in cable jackets are impractical or weaken the assembly.
Innovation Solution
A flexible or compressible expansion joint, such as braided sleeving, is integrated between the bound ends of the fiber optic cable to allow helical compression of optical fibers when the cable jacket shrinks, maintaining tensile strength and protecting the fibers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the cable jacket is left continuous without gaps, then the mechanical strength and reliability of the assembly is maintained, but the optical fibers undergo microbending due to jacket shrinkage which increases insertion loss
Solution Approach 1:
The cable jacket is segmented by removing a section to create a gap, allowing the jacket to shrink without transferring stress to the optical fibers. This segmentation prevents microbending while maintaining overall structural integrity through the expansion joint.
Solution Approach 2:
An expansion joint filled with flexible or compressible material acts as an intermediary element between the cable jacket sections. This mediator absorbs the shrinkage movement, preventing direct stress transmission to the optical fibers while maintaining mechanical continuity.
2Object-generated harmful factors
If a gap is left between cable jacket end and transition unit to prevent microbending, then insertion loss is reduced, but the assembly develops mechanical weakness that reduces reliability
Solution Approach 1:
The expansion joint serves as a mediator that fills the gap between cable jacket sections, preventing mechanical weakness while allowing the jacket to shrink freely. The flexible material maintains structural continuity without transmitting stress to the fibers.
Solution Approach 2:
The expansion joint utilizes flexible or compressible material that can deform to accommodate jacket shrinkage while maintaining mechanical strength. This flexible element prevents the assembly from developing weak points at the gap location.
3Stability of the object's composition
If the cable jacket shrinks at elevated temperatures, then the jacket stabilizes its structure, but the constrained optical fibers undergo microbending that increases insertion loss
Solution Approach 1:
By segmenting the cable jacket with a removable section, the jacket can shrink and stabilize at elevated temperatures without transmitting stress to the optical fibers. The segmentation creates a discontinuity that breaks the stress transmission path.
Solution Approach 2:
The expansion joint with flexible material acts as an intermediary that absorbs the thermal shrinkage movement, allowing the jacket to stabilize its structure while preventing microbending of the constrained optical fibers.
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 expansion joint effectively compensates for cable jacket shrinkage across varying temperatures without degrading optical performance, ensuring the fiber optic cable's reliability and tensile strength.
Implementation Method 1
When subjected to elevated temperatures, the cable jackets of these loose tube fiber optic cables shrink
Implementation Method 2
the expansion joint allows the plurality of optical fibers within the fiber optic cable to helically compress when the cable jacket shrinks
Implementation Method 3
The expansion joint may be made up of flexible or compressible material which covers an opening in the cable
Data Source
AI summary
A cable is provided having an expansion joint. The cable includes a cable jacket which makes up an outer layer of the cable, a non-end section where the cable jacket is removed from the cable which forms an opening, and an expansion joint which covers the opening and is bonded to the cable jacket at opposite sides of the opening. The expansion joint is made up of a flexible or compressible material.