Optical Fiber Cable With Nested Subunits for High Density
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Solution Overview
Problem
Existing optical communication cables face challenges in supporting a high density of optical fibers while maintaining fire resistance and low latency/skew, as the number of fibers increases, leading to issues with burn resistance and uneven tension distribution.
Innovation Solution
The optical communication cable design features a three-tiered structure with fire-resistant materials, including a cable jacket, bundle jacket, and subunit jacket, along with differential tensile strength strands and wrapping patterns to ensure equal fiber lengths and tension distribution, allowing for high fiber density and low skew characteristics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If the number of optical fibers is increased to achieve high fiber density, then the fiber count increases, but the burn resistance and fire safety deteriorate
Solution Approach 1:
The cable is divided into multiple independent subunits, each containing a limited number of optical fibers (e.g., 12 fibers per subunit). These subunits are individually jacketed and then grouped into bundles, which are finally assembled into the complete cable. This segmentation allows fire resistance to be maintained at the subunit level while achieving high overall fiber density through the combination of multiple subunits.
Solution Approach 2:
The cable structure employs a nested arrangement where optical fibers are contained within subunits, subunits are contained within bundles, and bundles are contained within the outer cable jacket. This nested doll-like structure enables high fiber density by efficiently packing multiple hierarchical levels, while each hierarchical level provides fire resistance, thereby maintaining safety even as total fiber count increases.
2Quantity of substance
If the number of optical fibers is increased to achieve high fiber density, then the fiber count increases, but the cable diameter increases
Solution Approach 1:
The nested hierarchical structure (fibers within subunits, subunits within bundles, bundles within cable) enables efficient space utilization. By organizing fibers into compact subunits with tight buffer coatings and using concentric bundle arrangements, the cable achieves high fiber density without proportionally increasing diameter, as the nested structure minimizes wasted space between fibers.
Solution Approach 2:
The cable employs three-dimensional bundle stacking and concentric ring arrangements of bundles around a central strength member. This spatial optimization in multiple dimensions allows high fiber counts to be packed into a compact cross-sectional area, preventing linear scaling of diameter with fiber count by utilizing efficient geometric packing arrangements.
3Quantity of substance
If the number of optical fibers is increased to achieve high fiber density, then the fiber count increases, but the tension distribution becomes uneven
Solution Approach 1:
The cable incorporates multiple independent tensile strength members (such as aramid yarns or steel wires) distributed throughout the bundle structure. Each subunit and bundle is supported by its own tensile strength elements, which segment the load-bearing function across multiple points rather than relying on a single central strength member. This segmentation ensures uniform tension distribution even as fiber count increases.
Solution Approach 2:
The cable structure is designed so that all subunits and bundles are positioned at equivalent mechanical positions relative to the tensile strength members. The symmetric arrangement of bundles around the central axis and the distributed placement of strength members create equipotential stress conditions, ensuring that tension is evenly distributed across all fibers regardless of their position in the high-density configuration.
4Quantity of substance
If the number of optical fibers is increased to achieve high fiber density, then the fiber count increases, but the skew and latency increase
Solution Approach 1:
The cable is divided into multiple subunits with each subunit containing a manageable number of fibers (e.g., 12 fibers). This segmentation allows for precise control and matching of fiber lengths within each subunit during manufacturing. By keeping subunit lengths equal and using differential length compensation techniques at the bundle level, the overall skew between fibers across all subunits is minimized, maintaining low latency even with high total fiber counts.
Solution Approach 2:
The cable employs differential length compensation by adjusting the length of subunits and bundles in a controlled manner. By carefully selecting and matching the axial lengths of subunits and their wrapping patterns within bundles, the patent compensates for path length differences that would otherwise cause skew. This parameter optimization ensures that all fibers, regardless of their position in the high-density cable, have substantially equal optical path lengths.
Data Source
AI summary
An optical communication cable is provided. The optical communication cable includes an outer cable layer and a plurality of optical fiber bundles surrounded by the outer cable laver. Each optical fiber bundle includes a bundle jacket surrounding a plurality of optical fiber subunits located within the bundle passage. The plurality of optical subunits are wrapped around each other within the bundle passage forming a wrapped pattern. Each optical fiber subunit includes a subunit jacket surrounding a elongate optical fiber located within the subunit passage. The cable jacket, bundle jacket and subunit jacket may be fire resistant, and strength strands of differing lengths may be located in the bundles and the subunits.