Spectral Beam Combiner with Split Paths for Wavelength Stabilization
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Solution Overview
Problem
Existing spectral beam combiners have coincident output and feedback paths, which limits wavelength stabilization and optical power coupling efficiency, as long cavity lengths are required for stability but conflict with maximizing power transfer.
Innovation Solution
Separate wavelength stabilization and output signal paths using a diffraction grating to direct a majority of the combined beam into a high-power output path and a residual beam into a separate path for stabilization, allowing independent optimization of both paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If a long cavity length is used for wavelength stabilization, then wavelength stability is improved, but optical power coupling efficiency deteriorates
Solution Approach 1:
The patent divides the optical path into two separate paths: one for wavelength stabilization (feedback path) and one for high-power output (signal path). The diffraction grating segments the combined beam, directing most power to the output path while routing a portion to the stabilization path. This segmentation allows each path to be optimized independently for its specific function.
Solution Approach 2:
The patent extracts the wavelength stabilization function from the high-power output path by creating a separate feedback path. A portion of the combined beam is extracted and routed through a separate optical path with a long cavity length for stabilization, while the majority of power remains in the output path for efficient coupling.
2Adaptability or versatility
If a diffraction grating is used for spectral combining, then wavelength-dependent combining is achieved, but thermal energy generation increases
Solution Approach 1:
The patent introduces a wavelength stabilization path as an intermediary mechanism that monitors and stabilizes the wavelengths before they enter the high-power output path. This intermediary feedback loop reduces wavelength drifts that would otherwise cause de-focusing and reduce system efficiency, thereby reducing thermal energy generation in the diffraction grating.
3Device complexity
If the output path and feedback path are coincident, then device complexity is reduced, but independent optimization of both paths is prevented
Solution Approach 1:
The patent segments the optical paths using a diffraction grating that directs different portions of the combined beam into separate paths. The feedback path and output path are spatially separated, allowing independent optimization of cavity length for stabilization versus coupling efficiency for power extraction, while maintaining relatively simple device architecture.
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 wavelength stability and optical power coupling efficiency by minimizing thermal energy generation and reducing the need for cooling, leading to higher mechanical and spectral stability and longer diode lifetime.
Implementation Method 1
a diffraction grating disposed to intercept the plurality of laser beams, where the diffraction grating is configured to direct a majority of the optical power of each beam into a defined first diffraction order
Implementation Method 2
a high-reflectivity (HR) mirror disposed along the stabilization path at a spaced-apart distance L from the turning mirror, the spaced-apart distance L selected to form a resonant cavity with the plurality of individual laser beam sources and provide wavelength stability
Data Source
AI summary
A spectral beam combiner is based upon a specialized diffraction grating that is intentionally configured to create output signals along two separate paths, each path supporting a spectrally-combined beam. One path supports the propagation of a majority of the spectrally-combined beam (e.g., 80-95%) and is defined as the output path from the beam combiner. The remainder of the spectrally-combined beam is directed along a separate path and into an external cavity arrangement used to perform wavelength stabilization. Either reflective or transmissive diffraction gratings may be used, with different diffraction orders and/or polarization states of the spectrally-combined optical beam used to create the output beam and the separate wavelength stabilization feedback beam.