Multicore Optical Fiber Preform Assembly for Core Alignment
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Solution Overview
Problem
Existing methods for forming preforms for multicore optical fibers are costly and difficult to maintain uniformity and precise positioning of core canes, leading to challenges in producing multicore optical fibers with consistent dimensions and alignment.
Innovation Solution
A method involving arranging core canes with contacting outer surfaces to form a preform assembly, fusing at selected locations, and creating a corrugated exterior surface to draw multicore optical fibers without a substrate tube, ensuring precise and consistent core positioning and dimensions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If holes are drilled in a cylindrical glass body to form preforms, then core canes can be positioned within the glass body, but expensive ultrasonic drilling machines are required and uniformity becomes difficult to maintain as drilling depth increases
Solution Approach 1:
Instead of drilling holes into a solid glass body to accommodate core canes, the invention inverts the approach by forming a hollow cylindrical glass body with an internal cavity that naturally receives and positions core canes. This eliminates the need for expensive ultrasonic drilling equipment while maintaining positioning precision, as the cavity is formed during the glass body creation process rather than through subsequent drilling operations.
2Ease of manufacture
If the stack-and-draw method is used to form preforms, then core canes and cladding rods can be stacked into a substrate tube, but the dimensions and positions of core canes are altered during fusing, making uniform sizing and placement difficult
Solution Approach 1:
The invention applies preliminary action by pre-positioning core canes within the hollow cylindrical glass body before the fusing process, using the internal cavity structure to maintain their positions. The cavity acts as a predetermined framework that guides and constrains core canes during assembly and fusing, preventing dimensional changes and position alterations that occur in conventional stack-and-draw methods.
3Manufacturing precision
If core canes are machined to have flat surfaces to improve alignment, then positioning in the preform assembly is improved, but a costly machining process step is added
Solution Approach 1:
The invention extracts the alignment function from the core canes themselves and transfers it to the hollow cylindrical glass body's internal cavity structure. Instead of modifying core canes with flat surfaces through machining, the cavity provides the alignment reference surfaces, eliminating the need for costly machining operations while maintaining precise alignment during assembly and fusing.
4Productivity
If preform length is increased to provide higher transmission capacity, then more core elements can be included, but it becomes increasingly difficult to maintain uniformity of holes as drilling depth increases
Solution Approach 1:
The invention resolves the limitation on preform length by inverting the hole formation approach. Instead of drilling holes through increasingly deep preforms (which loses uniformity), the hollow cylindrical glass body with internal cavity is formed first, then core canes are positioned within this cavity. This allows extended preform lengths to be manufactured while maintaining uniformity, as the cavity structure provides consistent geometric reference throughout the entire length.
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 method enables the production of multicore optical fibers with precise and consistent core positioning and dimensions along their length, overcoming the limitations of existing methods by reducing costs and improving uniformity.
Implementation Method 1
heating and fusing the core canes at selected locations along a contact zone defined by the contacting outer surfaces to form fusion regions that secure the core canes
Data Source
AI summary
A preform for multicore optical fiber is described. The preform includes an assembly of core canes arranged in a desired configuration. The core canes are placed in mutual contact with each other to define a series of contact zones between contacting pairs of core canes. The core canes are fused at selected locations within the contact zones to secure the core canes to form a preform from which a multicore optical fiber can be formed. The preform maintains good alignment of core canes and minimizes deformation of core canes during the fiber draw process. Multicore fibers having excellent uniformity in core diameter are produced from the preforms in conventional fiber draw processes.