Beam Shaper Array for High Fill Factor Fiber Laser Combining
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Fiber laser amplifier systems face challenges in combining beams to achieve a uniform phase over the beam diameter, leading to clipping losses and reduced fill factor, which affects the ability to focus the combined beam to a small spot effectively, especially in applications like directed energy weapons.
Innovation Solution
A hybrid spectrally and coherently combined fiber laser amplifier system with a beam shaper array assembly that includes spaced apart beam shaper arrays, converting round Gaussian beams to high fill factor beams while minimizing clipping losses, using beam shaper arrays to alter the spatial phase distribution and intensity profile of the beams.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple fiber laser amplifiers are combined to increase output power, then the power of the laser amplifier is improved, but the beam quality and uniform phase distribution deteriorate
Solution Approach 1:
The system divides the beam combining task into two separate segmentation stages: spectral beam combining (SBC) that segments beams by wavelength, and coherent beam combining (CBC) that segments beams by spatial phase. This two-stage segmentation allows each stage to optimize for its specific function, preventing the phase uniformity problems that would arise from attempting to combine all beams simultaneously in a single stage.
Solution Approach 2:
The patent introduces a hybrid combining approach that operates in two different dimensions: SBC combines beams in the spectral dimension (different wavelengths) while CBC combines beams in the spatial phase dimension (phase coherence). By operating in separate dimensions, the system avoids the trade-off between power scaling and phase uniformity that plagues single-dimension combining approaches.
2Power
If beam combining is performed without proper phase uniformity, then the power scaling is improved, but the ability to focus to a small spot deteriorates
Solution Approach 1:
The system performs preliminary phase uniformity adjustment in the CBC stage before the final beam combination. By pre-establishing uniform phase relationships across all laser amplifiers through phase locking and beam shaping, the system ensures that when beams are combined for power scaling, they will naturally focus to a small spot without requiring additional corrective optics.
Solution Approach 2:
The patent introduces beam shaping optics as an intermediary element between the laser amplifiers and the final beam combination point. These optics actively manipulate the phase and amplitude distributions of individual beams to ensure uniform phase relationships, acting as a mediator that enables both power scaling and tight focusing to occur simultaneously.
3Device complexity
If traditional beam combining approaches are used, then the system complexity is reduced, but the beam quality and fill factor deteriorate
Solution Approach 1:
The complex beam combining task is segmented into two manageable subsystems: SBC and CBC. Each subsystem has a dedicated function and can be optimized independently, reducing the overall system complexity compared to attempting to design a single monolithic beam combining system that must handle all aspects of power scaling and phase control simultaneously.
Solution Approach 2:
The hybrid SBC-CBC system serves multiple functions that traditional single-approach systems cannot achieve: it simultaneously provides power scaling, phase uniformity control, beam quality maintenance, and high fill factor. This multi-functionality is achieved through the complementary nature of SBC and CBC, where each approach contributes its strengths to the overall system performance.
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 system achieves a nearly 100% fill factor with uniform intensity and phase across the emitting aperture, enabling high-speed beam steering and compensation for atmospheric aberrations, reducing clipping losses and enhancing beam quality for focused output.
Implementation Method 1
beam shaper arrays, converting round Gaussian beams to high fill factor beams while minimizing clipping losses, using beam shaper arrays to alter the spatial phase distribution and intensity profile of the beams
Implementation Method 2
spectral beam combining (SBC), where multiple lasers of different wavelengths are combined on a diffraction grating or other dispersive optic into a single beam
Implementation Method 3
coherent beam combining (CBC), where multiple mutually coherent lasers are locked in phase with one another and combined into a single beam either by overlapping in the near field using a beam splitter
Data Source
Figure 1
Figure 2~3
Figure 4A~4D
AI summary
A hybrid coherent beam combining (CBC) and spectral beam combining (SBC) fiber laser amplifier system including a beam shaper array assembly and a beam source that provides a plurality of beams having a low fill factor profile. The assembly includes an input beam shaper array having a plurality of rectilinear input cells positioned adjacent to each other that are shaped to cause the beam to expand as it propagates away from the input array to be converted from the low fill factor profile to a high fill factor profile. The assembly further includes an output beam shaper array having a plurality of output cells positioned adjacent to each other that are shaped to cause the beam to stop expanding so that the output array provides a plurality of adjacent beams with minimal overlap and a minimal gap between the beams.