Laser Beam Shaping for Optical Fiber Coupling
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Solution Overview
Problem
Existing optical systems fail to provide a satisfactory range of propagation angles and uniform illumination in optical fibers, especially for high numerical aperture fibers, leading to non-uniform illumination patterns and potential fiber damage due to high power density.
Innovation Solution
Incorporating a beam diverging element, such as a diffuser or diffractive optical element, into the focusing optics to control the spatial and angular profiles of collimated laser light, allowing it to match the fiber's numerical aperture and spot size, and using fiber coupling optics to direct the diverged light into the fiber core with an elliptical cross-section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If focusing a beam with high NA optics, then a large range of propagation angles is achieved, but a small focal spot is produced
Solution Approach 1:
The patent divides the illumination function into two separate optical paths: one path (through the first objective lens) focuses light to a small spot for high propagation angles, while another path (through the second objective lens) focuses light to a large spot for uniform illumination. This segmentation allows both contradictory requirements to be satisfied simultaneously by using multiple optical channels.
Solution Approach 2:
The patent transitions from a single-point focus to a two-dimensional illumination plane by using a microlens array that creates multiple focal points across the fiber core face. This dimensional expansion allows the system to provide both high NA coupling and uniform spatial distribution across the entire core area.
2Area of moving object
If focusing a beam with optics designed to produce a large focal spot, then a large spot illuminating most of the core is achieved, but a small range of propagation angles is produced
Solution Approach 1:
The patent uses separate objective lenses for different illumination requirements: the second objective lens provides large spot size for uniform spatial illumination, while the first objective lens provides high NA for large propagation angle range. This segmentation resolves the contradiction by assigning different functions to different optical components.
Solution Approach 2:
The patent combines the outputs of multiple objective lenses and a microlens array to achieve both large spot size and high propagation angles simultaneously. The merged illumination from multiple focal points covers the entire fiber core while maintaining high NA coupling efficiency.
3Productivity
If using a small spot near the edge of the core, then coupling efficiency is improved, but spatially or angularly non-uniform illumination pattern is produced
Solution Approach 1:
The patent transforms a single-point coupling approach into a multi-point distributed coupling scheme using a microlens array. This creates multiple focal points across the fiber core face, maintaining high coupling efficiency at each point while achieving uniform spatial distribution across the entire core area.
Solution Approach 2:
The patent applies different illumination characteristics to different regions of the fiber core. Each microlens focuses light to a specific location on the core face, providing high local coupling efficiency, while the collective arrangement of multiple microlenses ensures uniform overall illumination across the entire core.
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 solution achieves a controlled range of propagation angles and reduces power density at the fiber entrance, ensuring uniform illumination and preventing fiber damage, while allowing for higher power transmission and spatially uniform patterns.
Implementation Method 1
a beam diverging element configured to diverge the laser light to yield a range of propagation angles
Implementation Method 2
a beam diverging element, such as a diffuser or diffractive optical element
Implementation Method 3
fiber coupling optics configured to direct the diverged laser light towards a spot of a cross-section of a fiber core
Data Source
AI summary
Certain embodiments may include a laser system configured to emit collimated laser light, a beam diverging element configured to diverge the laser light to yield a range of propagation angles with a maximum angle greater than zero, and fiber coupling optics configured to direct the diverged laser light towards a spot of a cross-section of a fiber core of an optical fiber. As another example, certain embodiments may include a laser system configured to emit collimated laser light, a beam shaping element configured to shape the laser light into a beam with an elliptical cross-section, and fiber coupling optics configured to direct the diverged laser light towards a spot of a cross-section of a fiber core of an optical fiber, where the spot's center point is located at a distance from the cross-section's center point.