Walk-off Pump Coupler for Reliable Beam Alignment
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Solution Overview
Problem
Conventional methods for coupling unpolarized pump beams and linearly-polarized signal seeds into waveguide amplifiers require dichroic mirrors, which are sensitive to shock, vibration, and temperature changes, increasing the complexity and weight of the coupling assembly.
Innovation Solution
A beam coupler system that includes a first beam displacer, a dual-wavelength waveplate, and a second beam displacer, which spatially translates and recombines the polarization components of the unpolarized pump beam to co-locate it with the linearly-polarized signal seed without using dichroic mirrors, thereby maintaining reliability across environmental changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If dichroic mirrors are used to couple pump beams and signal seeds into waveguide amplifiers, then the coupling function is achieved, but the system becomes sensitive to shock, vibration, and temperature changes
Solution Approach 1:
The patent removes dichroic mirrors from the optical coupling system entirely. Instead of using mirrors to combine pump and signal beams, the invention employs direct free-space coupling through precisely positioned fiber assemblies that insert beams independently into the waveguide amplifier, eliminating the problematic component that caused sensitivity to environmental disturbances
Solution Approach 2:
The patent introduces precisely positioned fiber assemblies as intermediary elements that directly insert pump and signal beams into the waveguide amplifier core. These fiber assemblies act as mediators that eliminate the need for dichroic mirrors by providing a direct coupling path, thereby removing the source of environmental sensitivity while maintaining effective beam combination
2Reliability
If additional turning mirrors are added to keep pump beam incidence near-normal on dichroic mirrors, then the coupling function is maintained, but the size and weight of the coupling assembly increase
Solution Approach 1:
The patent removes turning mirrors and dichroic mirrors from the system. By using direct free-space coupling through fiber assemblies, the invention eliminates the entire mirror-based optical path, thereby removing the weight penalty associated with additional optical components while maintaining stable coupling functionality
3Productivity
If dichroic mirrors are used for coupling pump beams and signal seeds, then beam combination is achieved, but the device complexity increases due to alignment sensitivity and environmental constraints
Solution Approach 1:
The patent removes dichroic mirrors from the system, eliminating the complex alignment requirements and environmental constraints associated with mirror-based coupling. The direct free-space coupling method simplifies the device architecture while maintaining effective beam combination into the waveguide amplifier
Solution Approach 2:
The patent employs precisely positioned fiber assemblies as intermediary elements that directly insert pump and signal beams into the waveguide amplifier. This intermediary approach simplifies the coupling mechanism by eliminating the need for complex mirror alignments and environmental controls, thereby reducing device complexity while maintaining coupling efficiency
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 effectively co-locates unpolarized and polarized beams, enhancing reliability and reducing the system's sensitivity to environmental forces, eliminating the need for dichroic mirrors and their associated complexities.
Implementation Method 1
a first beam displacer having a first input end and a first output end, the first beam displacer being configured to receive at the first input end a linearly-polarized signal seed having a first wavelength, and an unpolarized pump beam having a second wavelength, the unpolarized pump beam including first and second linear polarization components, the first beam displacer being further configured to spatially translate the first linear polarization component of the unpolarized pump beam to co-locate the first linear polarization component of the unpolarized pump beam with the linearly polarized signal seed at the first output end
Implementation Method 2
a dual-wavelength waveplate interposed between the first output end of the first beam displacer and the second input end of second beam displacer, and configured to rotate polarizations of each of the first linear polarization component, second linear polarization component, and linearly polarized signal seed
Data Source
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AI summary
Method and apparatus for beam coupling. In one example, a beam coupler includes a first beam displacer configured to receive a linearly-polarized signal seed having a first wavelength, and an unpolarized pump beam having a second wavelength, the unpolarized pump beam including first and second linear polarization components, the first beam displacer being further configured to spatially translate the first linear polarization component to co-locate the first linear polarization component with the linearly-polarized signal seed, a second beam displacer configured to spatially translate the second linear polarization component and recombine the first and second linear polarization components of the unpolarized pump beam, and to co-locate the unpolarized pump beam with the linearly polarized signal seed, and a dual-wavelength waveplate interposed between the first and second beam displacer, and configured to rotate polarizations of each of the first linear polarization component, second linear polarization component, and linearly-polarized signal seed.