Capillary Taper Pump Coupler for Fiber Laser Efficiency
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Solution Overview
Problem
Existing optical couplers for fiber lasers suffer from high optical losses and beam quality degradation due to tapering of pump and signal fibers, which limits scalability and efficiency in high-power applications.
Innovation Solution
A fused all-glass pump coupler design using a capillary taper with parallel pump fibers and a signal feed-through fiber, where the capillary taper is formed by glass drawing or etching to maintain constant diameter ratio and ensure low-loss signal and pump light transmission without fiber tapering, allowing for efficient coupling and minimal beam quality degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pump fibers and signal fibers are tapered to achieve coupling, then coupling efficiency is improved, but beam quality is degraded and optical losses increase
Solution Approach 1:
The patent introduces a capillary tube as an intermediary component between the pump fibers and signal fiber. The capillary tube with its tapered structure acts as a mediator that enables efficient optical coupling without requiring the signal fiber itself to be tapered, thus maintaining beam quality while achieving high coupling efficiency. The capillary tube's inner diameter variation along its length provides the necessary optical field transformation.
Solution Approach 2:
The patent separates the coupling function from the signal transmission function by using distinct components: pump fibers for coupling, a capillary tube for field transformation, and an untapered signal fiber for low-loss signal transmission. This segmentation allows each component to optimize its specific function without compromising the others.
2Productivity
If pump fibers are tapered for coupling, then pump light coupling is improved, but microbending losses occur
Solution Approach 1:
The capillary tube serves as a protective intermediary that receives the tapered pump fibers while providing a smooth transition zone. This mediator allows the pump fibers to be tapered for efficient coupling without transmitting those taper-induced irregularities to the signal fiber, thereby preventing microbending losses in the signal path.
Solution Approach 2:
The patent isolates the tapered structure to only the pump fiber region within the capillary tube, while keeping the signal fiber completely untapered. This spatial segmentation ensures that pump coupling efficiency is optimized in one region without introducing microbending losses in the signal transmission region.
3Productivity
If fiber tapering is used for coupling, then optical coupling is achieved, but scalability to high power is limited
Solution Approach 1:
The capillary tube acts as a scalable intermediary structure that can accommodate multiple pump fibers and handle higher power levels. Its tapered design provides efficient optical coupling while its robust glass construction and larger dimensions compared to fiber cores enable scalability to high-power applications without the limitations of direct fiber-to-fiber tapering.
Solution Approach 2:
The capillary tube structure serves multiple functions: it provides optical field transformation, protects the tapered pump fibers, maintains mechanical stability, and enables scalability. This multi-functional design makes the coupling system adaptable to various power levels and configurations, enhancing versatility for high-power fiber laser applications.
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 solution achieves high pump coupling efficiency and low-loss signal feed-through, maintaining excellent beam quality and enabling scalable, high-power fiber lasers with reduced risk of microbending losses.
Implementation Method 1
the capillary taper is formed by glass drawing or etching to maintain constant diameter ratio
Implementation Method 2
the capillary taper is formed by glass drawing or etching to maintain constant diameter ratio
Implementation Method 3
ensure low-loss signal and pump light transmission without fiber tapering
Implementation Method 4
The said capillary taper is then heated to make the glass soft and to form a collapsed region wherein the capillary taper has collapsed onto the signal fiber
Implementation Method 5
The said cleaved end is spliced to an output fiber so that cores of the signal fiber and the output fiber are essentially aligned
Data Source
AI summary
The invention relates to a pump coupler (2) and a manufacturing method. The pump coupler (2) comprises a least one signal fiber (50) for outputting optical energy, multiple pump fibers (31) for inputting optical energy into the signal fiber (50), and a coupling structure (40) for coupling the optical energy of the pump fibers (31) into the signal fiber (50). A signal feed-through fiber (32) goes through the coupling structure (40). In accordance with the invention the coupling structure (40) is a tapering capillary tube (40) having a first wide end (65) and a second narrow end (70), the pump fibers (31) are connected to the wide end of the capillary tube (40), and at least the narrow end (70) of the capillary tube (70) is collapsed around the signal fiber (32).