Core-to-Core Fusion Splice for High Efficiency Pump Combiner
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Solution Overview
Problem
Conventional fusion splicing of tapered fiber bundles to output fibers results in fiber distortion and reduced transmission efficiency due to mismatched cladding diameters, limiting the efficiency of pump power transfer in high-power fiber lasers and amplifiers.
Innovation Solution
A fusion splice configuration that removes a portion of the glass cladding from the output fiber to enable core-to-core fusion splicing, minimizing distortions and maximizing transmission efficiency by matching the core diameters of the tapered fiber bundle and output fiber.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional fusion splicing is used to connect tapered fiber bundle to output fiber, then the splice can be formed with cladding layers intact, but fiber distortion occurs and transmission efficiency decreases
Solution Approach 1:
The patent removes the cladding layer from a portion of the output fiber before fusion splicing. This extraction of the cladding layer eliminates the diameter mismatch between the tapered fiber bundle and output fiber, preventing core distortion and maximizing transmission efficiency (achieving 99% efficiency). The cladding is selectively removed only from the splicing region while preserving the protective cladding elsewhere on the fiber.
2Loss of energy
If cladding is removed from output fiber to enable core-to-core fusion, then transmission efficiency increases to 99%, but additional processing steps are required
Solution Approach 1:
The cladding removal is performed as a preliminary step before fusion splicing. By removing the cladding in advance, the actual splicing process becomes simpler and more precise, as it only requires aligning and fusing the cores without dealing with cladding diameter mismatches. The patent specifies removing cladding for a distance of 0.5-2mm from the end face, creating an optimized preparation state for high-efficiency splicing.
3Reliability
If cladding is completely removed from output fiber, then core-to-core fusion is achieved with minimal distortion, but fiber protection is reduced
Solution Approach 1:
The cladding removal is applied locally only to the specific region where fusion splicing occurs, rather than removing the entire cladding from the output fiber. The patent specifies removing cladding for a controlled distance of 0.5-2mm from the end face, which is sufficient to enable core-to-core fusion and minimize distortion, while the remaining cladding continues to provide mechanical protection and structural integrity to the fiber throughout its 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
This configuration achieves a transmission efficiency of 99% and reduces core distortion, enabling the delivery of pump powers exceeding 2 kW with improved system brightness and reliability.
Implementation Method 1
heating the joined portions of the optical input arrangement and the optical output fiber so as induce glass flow and create core-to-core fusion splicing
Implementation Method 2
heating the joined portions of the optical input arrangement and the optical output fiber so as induce glass flow and create core-to-core fusion splicing
Data Source
AI summary
A high efficiency optical combiner minimizes core region distortions in the area where fusion splicing between an input tapered fiber bundle (or any other type of “cladding-less” input fiber) and output fiber are joined. The thickness of the output fiber's glass cladding layer in the splice region is reduced (if not removed altogether) so that a core-to-core splice is formed and any necked-down region where the glass flows to join the core regions (while also joining the outer diameters) is essentially eliminated. The reduction of distortions in the core region of the splice improves the transmission efficiency between an input tapered fiber bundle and output fiber, reaching a level of about 99%. This high efficiency optical combiner is particularly well-suited for applications where a number of pump sources are combined and applied as an input to a fiber laser or amplifier.