Integrated Hollow-Core Preform for Precise Anti-Resonant Rings
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Solution Overview
Problem
The manufacturing of anti-resonant hollow-core optical fibers faces challenges in achieving accurate and reproducible production due to complex internal geometric shapes and minimal geometric deviations, leading to higher transmission loss and difficulty in producing an anti-resonant layer with a smaller wall thickness.
Innovation Solution
An integrated hollow-core optical fiber preform is fabricated by drilling axial holes in a jacket tube, followed by a hot-drawing process with controlled gas pressure to form anti-resonant rings with negative curvature, using a method that avoids the introduction of additional materials to ensure precise positioning and reduce contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional manufacturing methods are used to create anti-resonant hollow-core optical fibers, then the internal geometric shapes can be formed, but the positioning accuracy is poor and geometric deviations are minimal, making it difficult to produce accurately and reproducibly
Solution Approach 1:
The preform is segmented into multiple functional components: a jacket tube with axial holes, capillary tubes inserted into the holes, and a central rod. This segmentation allows each component to be manufactured and positioned separately with high precision, then assembled together. The capillary tubes form the anti-resonant layers with controlled wall thickness, while the jacket tube provides the hollow core structure. This modular approach resolves the contradiction by enabling precise positioning despite geometric complexity.
Solution Approach 2:
The capillary tubes are inserted into the axial holes of the jacket tube before the hot-drawing process. This preliminary positioning ensures that the anti-resonant layers are pre-aligned with the correct geometry and spacing. The preform is prepared in advance with all components in their final relative positions, so that during drawing, the structure is simply scaled down without introducing positioning errors. This resolves the contradiction by establishing precise geometry before the forming process.
2Loss of energy
If the anti-resonant layer has a smaller wall thickness to achieve lower loss and wider bandwidth, then the transmission performance is improved, but it becomes more difficult to manufacture with accurate dimensions
Solution Approach 1:
The capillary tubes serving as anti-resonant layers are designed with self-supporting walls that maintain their predetermined wall thickness during the hot-drawing process. The capillary tubes' rigid structure allows them to resist compression and maintain their dimensional integrity even when the overall preform is being drawn down to fiber dimensions. This self-supporting capability enables the manufacture of thin-walled anti-resonant structures without requiring complex external support or control mechanisms, resolving the contradiction between thin walls and manufacturability.
3Ease of manufacture
If additional materials are introduced to form the anti-resonant layer, then the structure can be built, but contamination increases and positioning accuracy decreases
Solution Approach 1:
The invention uses capillary tubes made of the same material (quartz) as the jacket tube and central rod. This material homogeneity eliminates contamination from foreign materials and ensures uniform thermal and mechanical properties throughout the preform. The capillary tubes are chemically and physically compatible with the surrounding structure, allowing them to be integrated without introducing impurities or interface problems. This resolves the contradiction by using additional structural elements (capillary tubes) that do not compromise precision or introduce contamination.
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 achieves a hollow-core optical fiber with low transmission loss (≤30 dB/km) and minimal wall thickness of anti-resonant rings, enhancing the accuracy and reproducibility of the manufacturing process.
Implementation Method 1
feeding a gas into the axial holes to create a gas pressure in each of the axial holes higher than that in a center hole of the jacket tube
Implementation Method 2
a pressure difference between each of the axial holes and the center hole of the jacket tube along with surface tension causes the drawn axial holes to protrude
Implementation Method 3
performing hot-drawing on the integrated hollow-core optical fiber preform obtained in step i)
Data Source
AI summary
The disclosure relates to an integrated hollow-core optical fiber preform, an optical fiber and a fabrication method thereof. Initially, holes are drilled to obtain a preform which is then subjected to a drawing process with gas fed into the drilled holes for pressurization control, resulting in an optical fiber with an anti-resonant ring structure. This method employs mechanical drilling to achieve precise positioning of the azimuth angle of the anti-resonant unit, ensuring axial uniformity and preventing any azimuthal shift during the drawing process. Furthermore, no additional materials are introduced for positioning the anti-resonant unit, thereby minimizing contamination from impurities and enhancing properties such as attenuation and strength of the optical fiber. Additionally, gas pressure control expands the anti-resonant unit during the drawing process, reducing its wall thickness and consequently lowering attenuation in this hollow-core optical fiber.