All-Fiber Laser Combiner with Tapered Sections
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Solution Overview
Problem
Current all-fiber laser combiners face challenges in achieving high packing density of multiple cores, leading to reduced optical brightness and increased costs due to the use of bulk optical components and mechanical systems, which limits their application in high-power industrial and medical settings.
Innovation Solution
An all-fiber laser combiner with a two-section tapered design, where the first section allows for high taper ratios without mode interaction, coupled with a second section for further beam reduction, enabling close core spacing and high optical density, allowing for the creation of a single supermode output or splitting of optical power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple singlemode fibers are bundled together to combine laser power, then the device achieves an all-fiber sealed unit structure with no moving parts, but the packing density of cores is very low (less than 1% core coverage) resulting in reduced optical brightness
Solution Approach 1:
The patent places multiple singlemode fiber cores inside a common multimode fiber core, creating a nested structure where the bundled cores are contained within the larger fiber. This nesting approach increases packing density while maintaining the all-fiber sealed structure, as the cores are efficiently arranged within the available cross-sectional area of the multimode fiber.
Solution Approach 2:
The patent transitions from a two-dimensional bundle arrangement to a three-dimensional core-in-fiber structure by embedding multiple cores within the volume of a single multimode fiber. This dimensional transformation allows for higher packing density and improved optical brightness while maintaining the compact all-fiber design.
2Quantity of substance
If fiber cores are tapered to reduce separation between cores, then packing density increases, but optical power leaks out of the core or couples into adjacent cores
Solution Approach 1:
The patent introduces a multimode fiber as an intermediary structure that receives light from multiple singlemode cores without requiring tight tapering. The multimode fiber's larger core acts as a buffer that captures and guides the combined optical power, allowing the individual cores to maintain adequate separation and preventing power leakage while still achieving high packing density.
Solution Approach 2:
The patent changes the numerical aperture and core size parameters along the fiber length by using a tapered multimode fiber section. The taper ratio of at least 3 allows the multimode core to transition from a larger diameter at the input (to capture light from multiple cores) to a smaller diameter at the output, increasing packing density while the gradual transition prevents optical power leakage through controlled mode coupling.
3Productivity
If bulk optical lenses and steering mirrors are used for beam combining, then beam combination is achieved, but cost and maintenance problems increase due to coated glass components and mechanical systems
Solution Approach 1:
The patent replaces mechanical beam combining systems (lenses, mirrors, steering mechanisms) with an all-fiber optical system. The fiber-based combiner uses evanescent coupling and mode matching to combine beams, eliminating moving mechanical parts and coated glass components while maintaining beam combination capability. This substitution reduces device complexity and maintenance requirements.
Solution Approach 2:
The patent merges multiple laser beams within the core structure of a single multimode fiber, combining the optical paths at the fiber level rather than using separate external optical components. This integration of multiple beams into a unified fiber-based structure eliminates the need for complex mechanical alignment systems and reduces the number of discrete components.
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 optical power concentration and density, reducing maintenance costs and enabling applications that require high power and uniform spatial intensity, such as cutting, welding, and medical treatments, while maintaining low numerical aperture and preventing mode interactions.
Implementation Method 1
The tapered end of the first tapered section couples to a second bundled section, which also may be tapered, comprising a bundle of multimode fibers or cores to provide further size reduction of the propagating beam
Implementation Method 2
maintaining a low NA along the length of the first tapered section and, further, preventing interaction between modes of the separate cores as well as preventing interaction between the modes and the outer boundary of any cladding surrounding the cores
Data Source
AI summary
An all-fiber combiner device is described for combining multiple high power inputs, such as high power laser inputs. The device includes a first tapered fiber section made from fibers that allow for efficient size reduction of the optical signals. The output of the first tapered fiber section may then be coupled to a multimode output fiber for delivery of the combined power beam. Alternately, the first tapered section can be coupled to a second, multimode, tapered section, which provides further size reduction of the core for splicing into a final output fiber, while adding cladding to the main fiber.