Heptagonal Optical Fiber Core for Uniform Laser Beam Profiles
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Solution Overview
Problem
Existing optical fibers do not adequately promote mode mixing, leading to non-uniform intensity distribution in laser beam profiles, which affects the efficiency of laser processing techniques like welding and cutting.
Innovation Solution
The optical fiber features a core with a heptagonal cross-section and corner portions having an R shape, where the diameter ratio between the circumscribed and inscribed circles satisfies a specific mathematical condition, promoting mode mixing and uniform intensity distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a conventional circular core cross-section is used, then the structure is simple and easy to manufacture, but mode mixing is insufficient and intensity distribution is non-uniform
Solution Approach 1:
The patent applies asymmetry by changing the core cross-section from a circular symmetric shape to an n-gonal asymmetric shape with specific corner portions having different curvature radii. This asymmetric geometry disrupts the symmetric propagation paths of light modes, enhancing mode mixing and achieving uniform intensity distribution at the output end of the optical fiber.
Solution Approach 2:
The patent applies local quality by making different corner portions of the n-gonal core cross-section have different curvature radii. Specifically, corner portions are designed with curvature radii satisfying specific relationships (e.g., r1 > r2, or r1 = k×r2 where 0.5 < k < 2.0). This local variation in geometric properties at different positions of the core enhances mode mixing effectiveness while maintaining manufacturing feasibility.
2Manufacturing precision
If mode mixing is insufficient, then the optical fiber structure is simpler, but the beam profile intensity distribution becomes non-uniform
Solution Approach 1:
The asymmetric n-gonal core cross-section with varying corner curvatures creates diverse and complex light propagation paths for different modes. This asymmetry prevents certain modes from dominating and ensures thorough mode mixing, thereby achieving uniform beam profile intensity distribution while maintaining structural simplicity.
Solution Approach 2:
The patent applies parameter changes by optimizing the curvature radii of corner portions according to specific mathematical relationships. By controlling parameters such as the number of sides n (5 ≤ n ≤ 12), and the curvature radius ratios between different corner portions, the patent achieves optimal mode mixing efficiency and uniform beam profile without excessive structural complexity.
3Reliability
If corner portions have sharp edges, then manufacturing is easier, but stress concentration occurs and mode mixing is reduced
Solution Approach 1:
The patent applies spheroidality by replacing sharp corner edges with curved portions having specific curvature radii. This curvature eliminates stress concentration points that would occur at sharp edges, improving fiber reliability. Simultaneously, the controlled curvature radii (with specific ratios between different corners) enhance mode mixing by creating varied reflection angles for propagating light modes.
Solution Approach 2:
The patent optimizes the curvature radius parameters of corner portions to balance manufacturing ease with performance requirements. By specifying that curvature radii satisfy certain relationships (e.g., r1 > r2, or 0.5 < k < 2.0 where r1 = k×r2), the patent ensures that corners are rounded enough to prevent stress concentration and promote mode mixing, while remaining within manufacturing capabilities.
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 enhances mode mixing, resulting in a uniform beam profile intensity distribution, improving the efficiency of laser processing by reducing light beam recirculation and stress concentration in the optical fiber.
Implementation Method 1
when mode mixing in the optical fiber is not sufficient, the intensity distribution may not be uniform
Data Source
AI summary
A process fiber including a core extending along a central axis and a clad covering a circumference of the core includes an outer edge portion constituting an outer edge of a core cross section obtained by vertically cutting the core. The outer edge portion includes seven sides and seven corner portions respectively connecting the sides adjacent to each other. Each of the corner portions has an R shape along a circumscribed circle circumscribed to the outer edge portion. When a diameter of the circumscribed circle is O, a diameter of an inscribed circle inscribed to the outer edge portion is I, and the number of the corner portions is n (n is an odd number), a diameter ratio α, which is a ratio between the diameter O of the circumscribed circle and the diameter I of the inscribed circle, fulfills a predetermined condition.