Optical Coupling Layout for Wavelength-Combined Fiber Laser Beams
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Solution Overview
Problem
The beam quality of combined laser beams deteriorates when focused onto an optical fiber, leading to decreased optical output power and efficiency, due to spherical aberration caused by the long optical path length, which results in a focus beam diameter larger than the core diameter of the fiber.
Innovation Solution
A light source device with an optical coupling device comprising a first cylindrical lens, a second cylindrical lens, and a third cylindrical lens, where the first beam parameter product along one direction is greater than the second along another direction, is used to focus the wavelength-combined beam, with the third lens having a focal length greater than the first, reducing spherical aberration and improving beam quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a long optical path length is used to focus the wavelength-combined beam, then the beam can be focused onto the optical fiber, but spherical aberration occurs causing beam quality deterioration and focus beam diameter enlargement
Solution Approach 1:
The optical path is divided into multiple segments by introducing cylindrical lenses at different positions. The first cylindrical lens focuses in the first direction, the second cylindrical lens focuses in the second direction, and the third cylindrical lens further focuses in the first direction. This segmentation allows the beam to be focused in steps rather than through a single long optical path, reducing spherical aberration while maintaining focusing capability.
Solution Approach 2:
Cylindrical lenses are introduced as intermediary optical elements between the beam combiner and the optical fiber. These intermediary lenses progressively focus the beam in different directions, acting as mediators that reduce the effective optical path length and minimize spherical aberration while still achieving the required focus at the fiber input.
2Productivity
If the focus beam diameter is reduced to match the fiber core diameter, then coupling efficiency increases, but spherical aberration from long optical path causes the focus beam diameter to enlarge
Solution Approach 1:
The focusing process is segmented into multiple stages using three cylindrical lenses with different focal lengths arranged at specific positions. This segmentation enables progressive reduction of the focus beam diameter while minimizing spherical aberration, achieving better coupling efficiency than a single-stage focusing system would allow.
Solution Approach 2:
The system uses cylindrical lenses with different focal lengths (first focal length, second focal length, and third focal length greater than the first) to change the focusing parameters progressively. By adjusting these focal length parameters and the distances between lenses, the system optimizes the focus beam diameter for maximum coupling efficiency while controlling spherical aberration.
3Power
If wavelength beam combining is used to increase optical output power, then the combined beam can be focused onto the fiber, but beam quality deteriorates due to spherical aberration
Solution Approach 1:
The optical path for the wavelength-combined beam is segmented into multiple focusing stages using three cylindrical lenses. This segmentation reduces spherical aberration that would otherwise deteriorate beam quality, enabling high optical output power from wavelength beam combining to be effectively coupled into the fiber while maintaining good beam quality.
Solution Approach 2:
Cylindrical lenses are introduced as intermediary elements that facilitate the coupling of high-power wavelength-combined beams into the optical fiber. These intermediaries reduce spherical aberration, allowing the system to maintain both high optical output power and acceptable beam quality simultaneously.
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 the beam quality and reduces the focus beam diameter, increasing the efficiency of optical coupling to the fiber, thereby maintaining high optical output power and preventing thermal damage.
Implementation Method 1
a first cylindrical lens configured to focus the wavelength-combined beam in a first plane containing the propagation direction and the first direction
Implementation Method 2
a second cylindrical lens configured to focus the wavelength-combined beam in a second plane containing the propagation direction and the second direction
Implementation Method 3
a third cylindrical lens configured to focus the wavelength-combined beam in the first plane so as to be incident on the first cylindrical lens
Data Source
Figure 1~2
Figure 3A~3B
Figure 4
AI summary
A light source device includes an optical fiber; a beam light source configured to coaxially combine laser beams of different peak wavelengths to generate and emit a wavelength-combined beam; and an optical coupling device configured to allow the wavelength-combined beam emitted from the beam light source to be incident on the optical fiber. The optical coupling device includes a first cylindrical lens configured to focus the wavelength-combined beam in a first plane and having a first focal length, a second cylindrical lens configured to focus the wavelength-combined beam in a second plane and having a second focal length, and a third cylindrical lens having a third focal length greater than the first focal length and configured to focus the wavelength-combined beam in the first plane to be incident on the first cylindrical lens.