Optical Fiber End Piece with Convex Spherical Curvature
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Solution Overview
Problem
Existing optical fiber end pieces, especially those with flat glass rods, fail to efficiently couple high-power laser radiation due to aperture errors and aberrations, leading to focus shifts and reduced power density at the glass-air interface, which complicates the design of subsequent optics.
Innovation Solution
An optical element with a convex spherical curvature, matching the refractive index of the fiber core, is attached to the optical fiber end, with a defined radius of curvature to length ratio (R=L*n/(n+1), reducing aperture and spherical aberration, and allowing for easier centering and reduced magnification in subsequent optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stress or pressure
If a flat glass rod is attached to the fiber end, then the power density at the glass-air interface is reduced, but aperture errors and spherical aberration increase leading to focus shifts
Solution Approach 1:
The patent applies a convex spherical curvature to the end face of the glass rod with a specifically optimized radius of curvature. This curvature is designed to compensate for spherical aberration while maintaining reduced power density at the interface. The spherical shape transforms the flat surface into an optical element that corrects aberrations without sacrificing the power density benefit.
Solution Approach 2:
The patent optimizes the radius of curvature parameter of the spherical end face to achieve the best compromise between reducing aperture errors and maintaining power density reduction. By carefully selecting this geometric parameter, the system achieves both goals simultaneously - correcting optical aberrations while keeping the beam aperture small enough to maintain high power density.
2Reliability
If complex shapes are proposed for the end face to optimize coupling, then coupling efficiency improves, but the manufacturing process becomes particularly important and complex
Solution Approach 1:
Instead of complex asymmetric shapes, the patent uses a simple convex spherical curvature that is much easier to manufacture. Spherical surfaces can be produced using standard polishing and grinding techniques, avoiding the need for complex computer-controlled shaping processes required for asymmetric optimized profiles.
Solution Approach 2:
The patent optimizes coupling efficiency by adjusting the radius of curvature parameter rather than changing the overall shape complexity. This single parameter optimization achieves good coupling performance while maintaining manufacturing simplicity.
3Shape
If the aperture of the radiated light is retained with a flat glass rod, then the virtual image of the fiber end face is maintained, but subsequent optics require higher magnification and become more complex
Solution Approach 1:
The convex spherical end face acts as a weak lens that slightly reduces the beam aperture while maintaining the virtual image of the fiber end face. This curvature modifies the light paths to reduce the divergence angle, allowing subsequent optics to operate at lower magnification and reducing overall system 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 optimally couples and decouples laser radiation, reducing aperture errors, spherical aberration, and power-dependent focus shifts, enabling efficient transmission of high-power laser radiation with a smaller beam parameter product and simpler optical system design.
Implementation Method 1
an optical element, which consists of a material identical to the core of the optical fiber or of an optical glass with a refractive index that corresponds to the refractive index of the fiber core, the side facing away from the fiber tip having a convex spherical curvature
Data Source
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AI summary
The piece (30) has an optical element made of a material identical with an internal core (13) of an optical fiber (11) or of an optical glass i.e. highly synthetic pure quartz glass, with a refractive index. The refractive index corresponds to a refractive index of the fiber core, and a side turned away from a fiber tip (14) has a convex spherical curvature (32). A curvature of an end face (31) of the piece and length of the optical element stand in a defined ratio to each other. Radius of curvature of the end face corresponds to the half length of the piece. An independent claim is also included for an optical fiber connection for coupling and uncoupling of laser radiation in an optical fiber.