First-order grating stack for 2D wavelength beam combining
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Solution Overview
Problem
Conventional two-dimensional wavelength beam combining systems using high-order Echelle gratings suffer from reduced efficiency and increased size, with limitations in packing density and high power handling, particularly for fiber lasers, leading to costly and complex optics.
Innovation Solution
The use of a first-order grating stack with unique groove densities and incidence angles replaces Echelle gratings, enabling higher beam combining efficiency and smaller size by spatially overlapping optical beams in two dimensions using cylindrical telescopes and transform lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If high-order Echelle gratings are used for two-dimensional wavelength beam combining, then wavelength dispersion capability is improved, but system size and complexity increase and beam combining efficiency decreases
Solution Approach 1:
The patent divides the single high-order Echelle grating into multiple first-order gratings arranged in a two-dimensional array. Each grating element operates in the first diffraction order, simplifying the diffraction mechanism while collectively achieving the wavelength dispersion function of the original Echelle grating. This segmentation reduces the complexity and size of individual grating elements.
Solution Approach 2:
The patent transitions from a one-dimensional Echelle grating configuration to a two-dimensional array of first-order gratings. By adding the spatial dimension, the system achieves wavelength dispersion through the combined effect of multiple gratings at different positions and orientations, replacing the high-order diffraction mechanism with a multi-element first-order diffraction approach.
2Measurement precision
If high-order Echelle gratings are used for wavelength beam combining, then spectral resolution is improved, but beam combining efficiency decreases
Solution Approach 1:
The patent segments the wavelength combining function across multiple first-order gratings rather than using a single high-order grating. Each grating element operates with higher diffraction efficiency in the first order, and the collective arrangement maintains spectral resolution through precise spatial positioning and angular orientation of each element in the array.
Solution Approach 2:
The patent changes the diffraction order parameter from high-order to first-order for all grating elements. This parameter change improves the diffraction efficiency and beam combining efficiency while maintaining spectral resolution through the two-dimensional spatial arrangement of the gratings, which compensates for the lower individual dispersion power.
3Adaptability or versatility
If conventional optics are used in wavelength beam combining systems, then system functionality is achieved, but cost and optical complexity increase
Solution Approach 1:
The patent makes each first-order grating element in the array serve multiple functions: wavelength dispersion, spatial beam combination, and spectral filtering. The two-dimensional arrangement allows the same grating structure to perform functions that would otherwise require separate optical components, reducing overall system complexity and cost while maintaining full functionality.
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 approach results in a more efficient, compact, and cost-effective two-dimensional wavelength beam combining system capable of handling high power, with reduced size and complexity, enhancing the power and brightness of multi-wavelength laser sources.
Implementation Method 1
a grating stack comprising a plurality of first-order diffraction gratings
Data Source
AI summary
A method and apparatus for two-dimensional wavelength beam combining of laser sources. In one example, an external cavity multi-wavelength laser includes an array of laser emitters each producing an optical beam having a specified wavelength, a grating stack comprising a plurality of first-order diffraction gratings arranged linearly in a first dimension, and a dispersive element. The laser further includes a cylindrical telescope that images the optical beams from the array of laser emitters onto the grating stack. A first cylindrical transform lens spatially overlaps the optical beams in a second dimension forming a first region of overlap at the grating stack. A second cylindrical transform lens spatially overlaps the optical beams from the grating stack in the first dimension forming a second region of overlap at the dispersive element. The dispersive element transmits a multi-wavelength output beam comprising the spatially overlapped optical beams from the array of laser emitters.