Birefringent Hollow-Core Fiber With Defect Cell Cladding
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Solution Overview
Problem
Existing hollow-core fibers face challenges in achieving low birefringence while maintaining polarization, as the use of a core tube affects core-web thickness and defect rods are prone to displacement, leading to increased loss and degradation of polarization-maintaining performance.
Innovation Solution
A birefringent hollow-core fiber is designed with a cladding comprising a matrix of cells, including lattice and defect cells arranged in a pattern to produce birefringence, where the capillary tubes at the core gap boundary are fused to form a microstructured cladding, allowing for controlled birefringence without a core tube, and defect capillary tubes are used to create a non-symmetrical geometry.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a core tube is added to an assembly of lattice capillary tubes with defect rods positioned at the inner circumference, then birefringence is successfully demonstrated, but the core-web thickness is impacted and defect rods are prone to displacement or detachment
Solution Approach 1:
The invention removes the core tube from the fiber structure entirely, extracting the element that causes instability. Instead, birefringence is achieved through defect capillary tubes integrated directly into the lattice at the core boundary, eliminating the core tube's negative impact on web thickness and rod stability.
Solution Approach 2:
The invention introduces asymmetry through defect capillary tubes with different wall thicknesses positioned at specific locations in the lattice. These asymmetric defect tubes create the necessary birefringence without requiring a core tube, and their fixed positions in the lattice prevent displacement during drawing.
2Reliability
If defect rods are positioned in a non-symmetrical pattern to create birefringence, then polarization control is achieved, but the defect rods are prone to becoming displaced or detached
Solution Approach 1:
The invention merges the defect elements directly into the lattice structure as integrated capillary tubes rather than separate rods positioned within a core tube. This integration ensures that defect tubes remain fixed in their non-symmetrical positions during the drawing process, eliminating displacement and detachment issues.
3Reliability
If a core tube is used in the fiber assembly, then birefringence can be achieved, but the core-web thickness is increased which affects performance
Solution Approach 1:
The invention extracts and removes the core tube from the fiber assembly, eliminating the source of excessive core-web thickness. Birefringence is maintained through defect capillary tubes positioned at the lattice boundaries, achieving the necessary optical properties without the thickness penalty of a core tube.
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
This approach results in improved polarization-maintaining properties with reduced variability in birefringence along the fiber length, minimizing loss and maintaining low-loss windows across a wide bandwidth, thus enhancing the fiber's performance in optical transmission and sensing applications.
Implementation Method 1
The cells at the core region boundary include lattice cells and defect cells that are arranged in a pattern so as to produce birefringence in a light propagating through the hollow core fiber
Implementation Method 2
the capillary tubes have been fused together to form a microstructured cladding surrounding a hollow core
Data Source
AI summary
A hollow core fiber has a cladding comprising a matrix of cells, wherein each cell comprises a hole and a wall surrounding the hole. The fiber further has a hollow core region comprising a core gap in the matrix of cells, wherein the core gap spans a plurality of cells and has a boundary defined by the interface of the core gap. The matrix of cells comprises a plurality of lattice cells, and a plurality of defect cells characterised by at least one difference in at least one property from that of the lattice cells. The cells at the core region boundary include lattice cells and defect cells that are arranged in a pattern so as to produce birefringence in a light propagating through the hollow core fiber. Further described is a technique for making the fiber.