Hollow Core Fiber End-Cap Assembly That Protects Microstructures
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Solution Overview
Problem
Existing end-cap assemblies for hollow core optical fibers suffer from damage to microstructures during splicing, leading to reduced coupling efficiency and stability, especially when used with high-power lasers, and manufacturing processes can damage optical surfaces.
Innovation Solution
An end-cap assembly comprising an elongated and hollow glass ferrule with a sealed second ferrule-end and an elongated solid end-cap, where the end-cap is attached inside the ferrule using arc-fusion to create a gas-tight seal, protecting the optical surfaces and maintaining stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If end-caps are directly spliced to the hollow core optical fiber, then the fiber-end is protected from contamination and fixed in position, but the microstructures of the HCF are damaged leading to collapse of the cladding and reduced coupling efficiency
Solution Approach 1:
A ferrule is introduced as an intermediary component between the end-cap and the hollow core optical fiber. The ferrule receives and secures the HCF while the end-cap seals the ferrule, preventing direct contact between the end-cap splicing process and the HCF microstructures. This mediator protects the HCF microstructures from damage during manufacturing while still providing contamination protection and positional fixation.
2Manufacturing precision
If splicing temperature is carefully controlled to prevent microstructure damage, then coupling efficiency is maintained, but stable laser output can only be provided for about an hour
Solution Approach 1:
The ferrule serves as a thermal buffer and mechanical support structure that isolates the HCF from thermal stresses during operation. By providing this intermediary structure, the system can maintain stable laser output for extended periods (over 1 hour) without the microstructure damage that limited previous direct-splice designs.
3Ease of manufacture
If end-cap is laser-welded to glass ferrule tube, then assembly is manufactured, but optical surfaces are damaged during manufacturing decreasing transmission
Solution Approach 1:
The assembly is segmented into distinct components (ferrule, end-cap, HCF) that can be manufactured and prepared separately. The ferrule and end-cap can be laser-welded or otherwise joined without exposing the HCF optical surfaces to damaging processes. This segmentation allows manufacturing of the assembly while protecting the critical optical surfaces of the HCF from damage.
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 assembly provides stable and efficient coupling of optical beams into and out of the hollow core optical fiber without damaging the microstructures, achieving transmission efficiencies over 85% even with high-power lasers, and preventing contamination.
Implementation Method 1
the end-cap is attached inside the ferrule using arc-fusion to create a gas-tight seal
Data Source
AI summary
Disclosed is an end-cap assembly for a hollow core optical fiber, comprising: an elongated and hollow glass ferrule comprising: a first ferrule-part with a first ferrule-end, and a second ferrule-part with a second ferrule-end, wherein the first ferrule-end configured to be sealed, and wherein the second ferrule-end is configured to receive a hollow core optical fiber, and wherein the second ferrule-part is configured to fix the hollow core optical fiber.