Multi-Channel Ferrule Design for Fiber Thermal Stress Reduction
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Solution Overview
Problem
Optical fibers connected through multi-fiber ferrules experience thermal stress due to differing coefficients of thermal expansion in materials like glass and metal alloys, leading to potential fiber breakage, especially when slots are wide.
Innovation Solution
A ferrule design with multiple narrow channels and uniform spacing between optical fiber longitudinal axes, minimizing thermal stress by maintaining lateral spacing and using a tapered channel structure with glass solder and UV-curable epoxy for stress relief.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If wide slots are used in the ferrule to accommodate multiple optical fibers, then the ferrule can accommodate a larger number of fibers, but the fibers experience increased thermal stress and may break
Solution Approach 1:
The patent divides the ferrule into multiple separate channels instead of using a single wide slot. Each channel accommodates a subset of optical fibers, thereby segmenting the large thermal expansion stress into smaller, manageable portions. This segmentation reduces the thermal stress experienced by individual fibers while maintaining the capability to accommodate a large total number of fibers.
2Ease of manufacture
If materials with different coefficients of thermal expansion are used in the ferrule, then the ferrule can be manufactured with diverse materials (glass, metal alloys, epoxy), but thermal stress is generated during solder glass reflow
Solution Approach 1:
By segmenting the ferrule into multiple narrow channels, the patent reduces the overall thermal stress generated during solder glass reflow. Each channel experiences less thermal stress individually, even when using materials with different coefficients of thermal expansion, thereby maintaining manufacturing flexibility while reducing stress.
Solution Approach 2:
The patent applies different materials (glass, metal alloys like Kovar, epoxy) to different parts of the ferrule structure, with each material selected for its specific local requirements. The multi-channel design ensures that local thermal expansion differences are contained within individual channels, preventing cumulative stress across the entire ferrule.
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
Reduces thermal stress and minimizes fiber damage by maintaining uniform spacing and using stress-relief materials, ensuring the fibers are not bent excessively and maintaining optical signal quality.
Implementation Method 1
a solder glass is inserted into the slot and melted or reflowed
Implementation Method 2
the materials that make up the ferrule (e.g., glass, metal alloys such as 'Kovar', and epoxy) have different coefficients of thermal expansion (CTE) and, thus, thermally expand at different rates
Data Source
AI summary
Consistent with the present disclosure, a ferrule is provided that includes first and second channels, for example. Multiple fibers of a ribbon cable, for example, are divided into groups and fed into corresponding channels of the ferrule. Since multiple channels are provided, however, each channel can be made relatively narrow. Thus, by providing smaller channel widths, the fibers in those channels experience less thermal stress. Moreover, the channels are spaced from one another so that the lateral spacing between adjacent fibers in the ribbon cable is maintained in the ferrule. As a result, the fibers are not bent laterally, and thus may experience little bending stress.