Multimode Laser Beam Combining for Long-Distance Radiant Intensity
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Solution Overview
Problem
Current directional infrared countermeasures (DIRCM) systems face challenges in maintaining high radiant intensity over long distances with compact semiconductor laser technology, as existing semiconductor lasers are limited to specific spectral bands, and multimode emitters provide insufficient radiant intensity due to poor beam quality.
Innovation Solution
The method involves combining the output of multiple multimode semiconductor laser diodes in radiant space to form a combined beam with a homogeneous non-Gaussian radiant intensity distribution across a selected solid angle, using spatially separated emitters and collimation optics to achieve partial overlap and enhance radiant intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If multiple multimode laser diodes are combined in radiant space, then system size is reduced, but beam quality deteriorates due to poor coherence and heterogeneous intensity distribution
Solution Approach 1:
Multiple multimode laser diode beams are combined in radiant space to achieve high total power output while maintaining compact system size. The beams are spatially overlapped and intensity-modulated to create a homogeneous combined beam pattern suitable for long-distance directional delivery.
Solution Approach 2:
Individual beam intensity distributions are modified locally through independent modulation of each laser diode's output. This allows compensation for the inherent poor beam quality of multimode diodes by creating a homogeneous overall intensity profile in the combined beam through precise local control of each component beam.
2Manufacturing precision
If single-spatial mode laser sources are used, then beam quality is improved, but output power is insufficient for long-distance directional delivery
Solution Approach 1:
Multiple lower-power multimode laser diodes are combined to achieve the total output power required for long-distance directional delivery. By merging multiple beams in radiant space with controlled intensity distribution, the system achieves both high power and adequate beam quality that single mode sources cannot provide alone.
3Illumination intensity
If conventional laser sources are used for long-distance delivery, then radiant intensity is maintained, but system complexity increases due to multiple pumping cascades and large footprint
Solution Approach 1:
The invention extracts and eliminates the complex multi-stage pumping cascades required by solid-state and fiber lasers. By using direct-emission semiconductor laser diodes combined in radiant space, the system achieves long-distance directional delivery capability without the bulky intermediate conversion stages, dramatically simplifying the overall system architecture.
Solution Approach 2:
Instead of using a single complex high-power laser source, the invention uses multiple simpler semiconductor laser diode sources that are copied and arranged in an array. Their beams are combined to replicate the functionality of a single complex source while maintaining much simpler individual components and overall system architecture.
4Productivity
If semiconductor laser diodes are used to cover wide spectral band, then system efficiency is improved, but spectral coverage is insufficient for complete DIRCM protection
Solution Approach 1:
The system achieves multi-spectral coverage capability through multiple laser diode sources that can be configured to emit at different wavelengths. This universal approach allows a single semiconductor-based system to provide comprehensive DIRCM protection across the entire spectral response window of missile seekers, replacing the need for different laser types for different spectral bands.
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 allows for radical reductions in system size, efficiency, and cost while maintaining high radiant intensity across a large area, effectively covering the spectral response window of missile seekers and enabling efficient long-distance laser delivery.
Implementation Method 1
combining the output of multiple multimode semiconductor laser diodes in radiant space so that the radiant intensity of the combined beam within a particular selected solid angle is sufficient for directional long distance laser delivery applications
Implementation Method 2
An individual multimode laser beam from each emitter is steered to partially overlap with at least one other multimode laser beam to form a combined beam
Data Source
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.