Toroidal Mirror Enhancement Resonator for High-Power Scaling
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Solution Overview
Problem
Conventional enhancement resonators face limitations in enlarging beam diameters and maintaining stability near the edges of their stability range, leading to astigmatism effects and mirror damage due to high intensity, which impede further power scaling for high-repetition-rate lasers.
Innovation Solution
The use of toroidal mirrors with different radii of curvature in the tangential and sagittal planes, combined with cylindrical mirrors, allows for a significant enlargement of beam diameters on all mirrors while adjusting ellipticity to avoid astigmatism, thereby reducing intensity and thermal gradients on mirrors, and enabling operation near the stability range edges with minimal sensitivity to maladjustments.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If conventional enhancement resonators are used with standard dielectric laser mirrors, then the resonator can operate with compact design, but the beam diameter on mirrors is limited and intensity-related mirror damage occurs at high powers
Solution Approach 1:
The patent employs toroidal mirrors with different radii of curvature in the tangential and sagittal planes, and cylindrical mirrors, to create a resonator configuration that naturally enlarges the beam diameter on all mirrors. This curvature-based geometric design transforms the beam propagation characteristics to achieve large spot sizes without requiring additional beam-expanding optics, thereby reducing intensity on mirror surfaces and preventing intensity-related mirror damage at high average powers
Solution Approach 2:
The patent changes the geometric parameters of the resonator by operating near the edges of the stability range with specifically designed toroidal and cylindrical mirror configurations. This parameter change enables beam diameters on mirrors to be enlarged by factors of 10 to 30 compared to conventional resonators, while maintaining stable operation and avoiding astigmatism effects through proper selection of radii of curvature
2Reliability
If the resonator operates near the edges of the stability range to achieve low sensitivity to maladjustments, then the configuration becomes more robust, but the stability margin is reduced
Solution Approach 1:
The patent introduces asymmetry in the mirror curvatures by using toroidal mirrors with different radii of curvature in the tangential and sagittal planes, combined with cylindrical mirrors. This asymmetric configuration creates a stable operating point near the edge of the stability range that is inherently less sensitive to maladjustments and vibrations, while maintaining adequate stability margin through the specific geometric relationships between the mirrors
3Object-affected harmful factors
If beam diameters are enlarged to reduce intensity on mirrors, then mirror damage is reduced, but astigmatism effects and beam shape deformation occur
Solution Approach 1:
The patent uses toroidal mirrors with different radii of curvature in the tangential and sagittal planes to compensate for astigmatism effects. The specific combination of toroidal and cylindrical mirrors creates a beam propagation path where the curvature-induced astigmatism is counterbalanced, maintaining a circular beam cross-section throughout the resonator while achieving large beam diameters on all mirrors, thus preventing both mirror damage and beam shape deformation
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 design achieves a beam diameter enlargement by a factor of 10 to 30, allowing for higher average power levels and optimized interaction volumes for nonlinear effects, such as high-order harmonic generation, with reduced mirror damage and improved phase matching, enabling the enhancement of femtosecond pulses to the MW average power level.
Implementation Method 1
generating intra-resonator laser light by coherent superposition (or: coherent addition) of laser light
Implementation Method 2
Passive optical resonators can be efficiently excited by laser light as its coherence allows for a constant phase relationship of the input laser light field with the field inside the resonator
Implementation Method 3
The conversion of the fundamental intra-cavity light upon a pass through a nonlinear medium represents round trip losses
Data Source
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AI summary
An enhancement resonator (20) being configured for generating intra-resonator laser light (1) by coherent superposition of input laser light, comprises at least three resonator mirrors (21, 22, 23, 24) spanning a ring resonator path in one common resonator plane, said resonator path being free of a laser light amplifying medium, wherein the at least three resonator mirrors (21, 22, 23, 24) include at least two toroidal mirrors and/or at least one cylindrical mirror. Furthermore, a laser device (100) comprising the enhancement resonator (20) and a method of generating intra-resonator laser light (1) are described.