Multimode Fiber Combiner Using Rectangular Gradient-Step Fibers
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing multimode fiber based beam combiners are sensitive to external perturbations, resulting in unstable output beam profiles, and typically produce circular beams, which are undesirable for applications requiring non-circular beam profiles such as direct materials processing.
Innovation Solution
The development of a multimode fiber based beam combiner using gradient-step fibers with independently positionable input portions and a bundled output surface, allowing for the creation of non-circular beam profiles with low modal content, such as square or rectangular shapes, and maintaining the intrinsic brightness of laser diode radiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If standard multimode fiber combiners are used, then beam combination is achieved, but the output beam profile becomes sensitive to external perturbations and changes dramatically with fiber movement
Solution Approach 1:
The patent applies asymmetry by using rectangular cross-section fibers instead of conventional circular fibers. This asymmetric geometry creates a stable far-field pattern that is inherently insensitive to fiber perturbations. The rectangular shape produces a characteristic four-lobe pattern in the far field that remains stable even when the fiber is moved or perturbed, directly resolving the contradiction between beam combination capability and sensitivity to external disturbances.
Solution Approach 2:
The patent changes the geometric parameters of the fiber cross-section from circular to rectangular, and controls the relative positioning of multiple rectangular fibers in the bundle. By adjusting parameters such as fiber spacing, orientation, and dimensions, the patent achieves a stable far-field pattern that is robust against perturbations while maintaining the desired beam combination function.
2Shape
If standard multimode fiber combiners are used, then beam combination is achieved, but the output beam profile is circular which is unsuitable for applications requiring non-circular profiles
Solution Approach 1:
The patent directly addresses the shape limitation by employing rectangular cross-section fibers arranged in specific geometric configurations. This asymmetric approach enables the generation of non-circular far-field patterns (such as four-lobe patterns) that are well-suited for materials processing applications requiring directional or patterned beam delivery, thereby improving both the shape characteristic and the adaptability to different processing requirements.
Solution Approach 2:
The patent applies local quality by arranging rectangular fibers with different orientations and positions within the bundle to create specific far-field patterns. Different regions of the fiber bundle can be configured with different orientations (e.g., some fibers horizontal, some vertical) to produce localized intensity distributions that combine to form the desired overall beam profile, enhancing versatility for various processing applications.
3Productivity
If circular fibers are used in the combiner, then standard fiber technology is utilized, but the output beam cannot provide the non-uniform dosage distribution required for certain materials processing applications
Solution Approach 1:
The patent resolves this contradiction by using asymmetric rectangular fiber cross-sections that naturally produce non-uniform far-field intensity distributions. The rectangular geometry creates characteristic four-lobe patterns with concentrated intensity in specific directions, enabling uniform dosage distribution across the material surface during scanning processes, thereby improving materials processing efficiency while achieving the desired beam profile uniformity.
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 provides a stable, non-circular output beam profile that is insensitive to external perturbations, optimizing beam delivery and processing uniformity in applications like direct materials processing.
Implementation Method 1
Beam combiners comprise at least a first optical fiber and a second optical fiber wherein at least one of the first and second optical fibers is a gradient-step fiber
Implementation Method 2
at least one of the first and second optical fibers is a gradient-step fiber
Data Source
AI summary
Multimode beam combiners include at least one gradient-step index optical fiber in which a refractive index difference at a core/cladding interface is selected to provide a numerical aperture so as to provide stable, uniform beam output. One or more such fibers is formed into a tapered bundle than can be shaped to provide a selected illuminated aperture. The fibers in the bundle can be separated by respective tapered claddings so as to be optically coupled or uncoupled. Illumination systems can include a plurality of such fibers coupled to a plurality of laser diodes or other light sources.