Radiant Beam Combining of Multimode Laser Diodes for Long-Range Delivery
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Solution Overview
Problem
Current semiconductor laser diodes in the 2.1-2.3 micron spectral region lack sufficient output power for long-distance laser delivery applications, and multimode emitters provide inadequate radiant intensity due to poor beam quality, while bulky solid-state or fiber laser technologies are required to cover this spectral range, compromising system size and efficiency.
Innovation Solution
A method of combining multiple multimode laser beams in radiant space using spatially separated broad area semiconductor laser diodes with individual collimation optics, achieving partial beam overlap to form a combined beam with homogeneous radiant intensity distribution within a selected solid angle, thereby enhancing radiant intensity and reducing system size and cost.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If single-spatial mode semiconductor laser diodes are used, then beam quality and radiant intensity are improved, but output power is insufficient for long-distance applications
Solution Approach 1:
The patent combines multiple single-mode laser diode beams in radiant space to achieve high output power while maintaining excellent beam quality. The individual beams are spatially overlapped and coherent-combined to produce a composite beam with both high power and high radiant intensity, resolving the contradiction between power and beam quality.
Solution Approach 2:
The system segments the high-power laser source into multiple lower-power single-mode laser diodes, each contributing to the overall beam. This segmentation allows each individual diode to operate in the optimal single-mode regime while the collective output achieves the required power level for long-distance applications.
2Power
If multimode semiconductor laser diodes are used, then output power is increased, but beam quality and radiant intensity deteriorate
Solution Approach 1:
The invention extracts the spatial mode structure from the multimode operation by using multiple separate single-mode diodes. Each diode operates in a clean single-mode regime, and the modal content is controlled at the source rather than attempting to manage complex multimode structures, thereby maintaining high radiant intensity while achieving high power through combination.
3Adaptability or versatility
If solid-state or fiber laser technologies are used to cover 2.1-2.3 micron spectral range, then spectral coverage is improved, but system size and complexity increase
Solution Approach 1:
The patent employs a universal approach by using multiple single-mode laser diodes that can be tuned or selected to cover the 2.1-2.3 micron spectral range. This multi-functional array of diodes replaces the need for bulky solid-state or fiber laser systems, achieving the same spectral coverage with a compact, integrated semiconductor-based platform.
4Adaptability or versatility
If multiple laser sources are combined to cover wide spectral band, then spectral coverage is improved, but system size increases
Solution Approach 1:
The system implements a nested architecture where multiple single-mode laser diodes are integrated into a compact array structure. The diodes are spatially arranged and optically combined in a nested configuration that minimizes the overall footprint, allowing wide spectral coverage to be achieved within a small area suitable for airborne DIRCM systems.
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 provides a compact, efficient, and cost-effective solution for directional infrared countermeasures and free-space communications by maintaining high and uniform radiant intensity across a large area, leveraging the higher output power of multimode emitters and achieving a 'top-hat' beam profile with improved resistance to environmental effects.
Implementation Method 1
combining a plurality of laser beams emitted by a plurality of laser beam emitters in radiant space to form a combined beam
Implementation Method 2
individual collimation optics for individually collimating and shaping individual laser beams
Data Source
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AI summary
A method and apparatus for beam combining for multiple multimode semiconductor laser diodes includes achieving beam combining in radiant space to provide a directional laser beam with a uniform high radiant intensity level distribution over a large area at a long distance from the source. The method uses more than one broad area high-power multimode semiconductor laser diode and individual optics for collimation, and includes combining the beams of these emitters to provide a relatively homogeneous radiant intensity beam at a long distance for applications such as directed energy delivery, free-space laser communication, and directional infrared countermeasures.