Fiber-to-Optical Element Alignment for Low-Loss Beam Combining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber laser amplifier systems face challenges in achieving high fill factors and low clipping losses when combining beams from multiple fiber amplifiers, leading to inefficiencies in beam focusing and beam quality, particularly in directed energy applications where high power and precise beam control are required.
Innovation Solution
The implementation of a beam shaper array assembly that transforms round Gaussian beams into square flat-top beams with a high fill factor, using tiled beam shaper arrays to minimize gaps and optimize beam intensity distribution, allowing for precise phase control and beam steering without physical deformation of optics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If round Gaussian beams are used from fiber amplifiers, then the beam generation is simple and efficient, but the fill factor is low and clipping losses are high
Solution Approach 1:
The beam generation process is segmented into two distinct stages: first generating round Gaussian beams from fiber amplifiers, then transforming them into square flat-top beams using beam shapers. This segmentation allows each stage to be optimized independently - the fiber amplifiers maintain their simple efficient operation while the beam shapers resolve the clipping loss issue.
Solution Approach 2:
The beam profile parameters are changed from round Gaussian to square flat-top through the beam shaper array. This parameter transformation increases the fill factor and reduces clipping losses while maintaining the simplicity of the original fiber amplifier design.
2Loss of energy
If beam shaper arrays are added to transform beams, then the fill factor increases to nearly 100%, but the device complexity increases
Solution Approach 1:
The beam shaper array is designed to be self-aligning through the self-service principle. The fabrication process inherently provides alignment features that guide the beam shapers into their correct positions and orientations, eliminating the need for complex external alignment mechanisms and reducing overall system complexity.
Solution Approach 2:
The beam shaper array integrates multiple functions into a single component structure - beam shaping, alignment reference, and mechanical support are merged into the beam shaper assembly. This consolidation reduces the number of separate components and simplifies the overall optical system.
3Ease of operation
If traditional deformable mirrors are used for beam steering, then the beam control is achieved, but the actuation speed is limited to acoustic-class speeds
Solution Approach 1:
The mechanical deformable mirror system is replaced with an optical beam shaper array system. Instead of physically deforming a mirror surface at acoustic speeds, the invention uses pre-fabricated beam shapers with inherent alignment features that enable faster beam control through optical rather than mechanical means.
Solution Approach 2:
The beam shapers are pre-fabricated with alignment features during manufacturing, so that when assembled, they automatically achieve the correct alignment without requiring real-time mechanical adjustment. This preliminary action during fabrication enables faster operational response compared to traditional deformable mirrors that require continuous mechanical actuation.
4Productivity
If fibers are welded to the optical element, then the beam combining is achieved, but the angle and position errors occur
Solution Approach 1:
The optical element serves as an intermediary component between the fiber array and the beam shaper array. It provides a stable mounting platform with reference features that mediate the alignment relationship, allowing fibers to be welded to it while maintaining precise angular and positional relationships through the reference features.
Solution Approach 2:
The alignment reference features on the optical element provide feedback during the assembly process. These features enable measurement and correction of fiber alignment errors, allowing the system to achieve high beam combining efficiency while compensating for welding-induced position and angle errors.
Data Source
AI summary
A system and method for fabricating an optical element. The method includes welding an array of fibers to the optical element, measuring an angle error and a position error of each fiber, calculating a correction for each fiber for the angle error and the position error and correcting the angle and position of each fiber using the calculated corrections.