Light Guide for High-Power Diode Laser Coupling
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Solution Overview
Problem
Coupling high-power diode laser radiation into optical fibers while maintaining beam quality is challenging due to the large divergence angle and slit-shaped emitters, leading to inefficiencies and potential thermal damage, especially with existing methods that require complex micro-optics or fiber deformation, which can result in mechanical instability and adhesion issues.
Innovation Solution
A light guide with a monolayer of optical fibers arranged on a carrier plate, where the fibers are positively connected to the plate in a fusion zone, transitioning to a circular cross-section, and then to a circular outlet zone, providing mechanical stability and minimizing gaps, thus allowing for efficient coupling with reduced mechanical stress and adhesion risks.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If collimation of laser radiation in the fast axis is implemented using micro-optics or conical light guide rods, then coupling efficiency into low-NA fibers is improved, but device complexity and mechanical stability deteriorate due to positioning requirements and fiber deformation
Solution Approach 1:
The patent extracts the collimation function from complex micro-optics and conical light guide rods, replacing it with a simplified planar interface structure. The light guide rod has a planar front surface that directly couples to the laser diode array without requiring precise positioning of additional optical elements, thereby eliminating positioning complexity while maintaining coupling efficiency.
Solution Approach 2:
The patent introduces a planar interface as an intermediary between the laser diode array and optical fibers. This planar interface serves as a stable coupling surface that simplifies the connection geometry, replacing the need for complex micro-optics and conical transformations, and providing mechanical stability through a rigid planar structure.
2Device complexity
If blunt coupling with high-NA fibers is used to avoid micro-optics, then device complexity is reduced, but beam quality deteriorates due to large divergence angle acceptance
Solution Approach 1:
The patent applies local quality by creating a planar interface with specific local geometric properties that optimize coupling. The planar front surface of the light guide rod provides a localized coupling region with controlled impedance matching and field distribution, enabling efficient coupling without requiring the entire system to have complex optics, thus preserving beam quality while simplifying the overall device.
3Loss of energy
If fiber deformation processes are applied to create conical cross-sections, then coupling efficiency is improved, but mechanical strength and reliability deteriorate due to fiber stress and adhesion risks
Solution Approach 1:
Instead of deforming the fibers to achieve conical cross-sections, the patent inverts the approach by keeping the fibers straight and cylindrical, and instead creating the conical light field transformation through the planar interface geometry of the light guide rod. This inversion eliminates fiber deformation and associated mechanical stress while achieving the same coupling objective.
4Loss of energy
If multiple fibers are assigned to each emitter with fused fiber bundles, then coupling efficiency is improved, but manufacturing precision and positioning accuracy deteriorate
Solution Approach 1:
The patent merges multiple emitters into a single light guide rod with a planar interface, rather than assigning individual fibers to each emitter. This consolidation simplifies the coupling structure to a single planar interface, eliminating the need for precise positioning of multiple individual fibers while maintaining efficient coupling of the combined emitter output.
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 enables efficient coupling of high-power diode laser radiation with minimal beam quality deterioration and mechanical stability, reducing the risk of thermal damage and fiber breakage, while allowing for conventional end surface processing like grinding and polishing.
Implementation Method 1
optical fibers with a coupling-in end and one or more coupling-out ends
Implementation Method 2
a fusion zone in which the fibers are at least partially connected to one another in a form-fitting manner
Data Source
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AI summary
The invention relates to a light guide for transmitting radiation, in particular the radiation from a high power diode laser, and to a method for producing the same. The light guide is characterized by a gap-shaped elongated light entry surface consisting of one or more layers of optical fibers, wherein the fibers are at least partly connected to one another and to a carrier plate in a form-fitting manner. The invention further relates to a method for producing the light guide according to the invention.