Fiber Coupler Geometry for Flat-Top Laser Beam Shaping
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Solution Overview
Problem
Current laser processing apparatuses face challenges in achieving a suitable beam shape for laser light output, which affects the quality and efficiency of laser processing tasks such as welding and cutting.
Innovation Solution
A laser processing apparatus is designed with a coupler that optically couples multiple multi-mode input optical fibers to a multi-mode output optical fiber, featuring a unique cross-sectional configuration where the cladding of the input fibers has an extending portion between cores, allowing for a flat-top intensity distribution of laser light, thereby achieving a more suitable beam shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional optical fibers with circular cladding are used, then the structure is simple and easy to manufacture, but the beam shape is not suitable for high-quality laser processing
Solution Approach 1:
The cladding structure is designed with different properties in different regions: the extending portion between adjacent cores has different dimensions compared to other regions. This local variation in cladding geometry enables selective light transmission characteristics that produce a flat-top beam profile at the output, resolving the contradiction between simple structure and high beam quality.
Solution Approach 2:
The cladding is designed with asymmetric geometry relative to the core positions, specifically with extending portions positioned between adjacent cores. This asymmetric configuration modifies the optical field distribution to achieve a flat-top intensity profile, transforming the conventional symmetric circular cladding into a structure that optimizes beam shape for laser processing.
2Adaptability or versatility
If multiple light sources are combined to improve processing versatility, then different wavelength bands can be used for different processing types, but the beam shape control becomes more difficult
Solution Approach 1:
The optical fiber bundle design with the specific cladding configuration serves multiple functions simultaneously: it combines light from multiple wavelengths while maintaining flat-top beam shape control. The extending portion structure enables this multi-functional operation by providing wavelength-independent beam shaping, allowing the same fiber bundle to support both thermal conduction-type and keyhole-type melting processes.
3Manufacturing precision
If the cladding extending portion is added to improve beam flatness, then processing quality improves, but the manufacturing complexity increases
Solution Approach 1:
The cladding extending portion is designed with specific dimensional parameters (length, width, position) that can be controlled during the fiber drawing process. By optimizing these parameters, the patent achieves flat-top beam output while maintaining compatibility with conventional fiber fabrication methods, thus improving processing quality without excessively increasing manufacturing complexity.
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 results in a high-quality laser processing with improved beam flatness, reduced spatter and defects, and enhanced processing stability by combining laser light from different wavelength bands, leading to more efficient thermal conduction-type and keyhole-type melting processes.
Implementation Method 1
a coupler configured to optically couple a first end of a bundle portion in which the at least two first input optical fibers are bundled so as to be aligned in a circumferential direction, to a second end of the output optical fiber
Implementation Method 2
at least one first light source optically connected to one of the first input optical fibers to output laser light, the at least one first light source being a multi-mode light source
Data Source
AI summary
A laser processing apparatus includes: at least two first input optical fibers; an output optical fiber; a coupler configured to optically couple a first end of a bundle portion, in which the at least two first input optical fibers are bundled, to a second end of the output optical fiber; at least one first light source optically connected to one of the first input optical fibers to output laser light; and an optical head optically connected to the output optical fiber to output laser light and passing through the first input optical fiber and the output optical fiber. In a cross section intersecting an axial direction of the first end, a cladding of the first input optical fiber has an extending portion extending linearly in a direction intersecting the axial direction between cores of two first input optical fibers adjacent in a circumferential direction.