Blue Laser Wavelength Multiplexing for Multi-kW Fiber Output
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Solution Overview
Problem
Infrared-based additive manufacturing systems face limitations in build volume and speed due to their characteristics, particularly when compared to high power blue, blue-green, and green lasers, which are more effective for materials processing and welding applications.
Innovation Solution
Development of high-power blue laser diode systems that launch over 100 Watts into a 50 to 200 μm fiber, with beam parameter products suitable for pumping Raman fiber lasers or processing materials through spectral beam combining techniques using various optical elements like volume Bragg gratings and dichroic filters, enabling efficient materials processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If infrared-based additive manufacturing systems are used, then the systems can operate with existing IR laser technology, but the build volume and build speed are limited
Solution Approach 1:
The patent changes the fundamental parameter of laser wavelength from infrared (>1000 nm) to blue (400-495 nm). This parameter change enables access to higher power laser sources and improves material absorption characteristics, thereby increasing both build speed and build volume in additive manufacturing applications
Solution Approach 2:
The patent employs pulse modulation of the blue laser diode array, switching between high-power pulsed operation and lower-power continuous operation. This periodic action allows the system to achieve high peak powers for rapid melting and consolidation (increasing build speed) while maintaining precise thermal control, thus resolving the contradiction between power output and processing quality
2Power
If high power blue laser diodes are used to increase power output, then laser power increases, but beam quality and coupling efficiency become more difficult to maintain
Solution Approach 1:
The patent divides the high-power laser source into multiple individual blue laser diodes (1-100s per array) that can be independently controlled and optimized. Each diode can be precisely coupled to its corresponding waveguide or fiber, maintaining high coupling efficiency while achieving multi-kilowatt total power through coherent or incoherent combination of multiple channels
Solution Approach 2:
The patent implements dynamic control of individual laser diodes within the array, allowing real-time adjustment of power levels, timing, and spatial distribution. This dynamic capability enables adaptive optimization of beam coupling efficiency under varying operating conditions while maintaining high total power output, resolving the contradiction between power scaling and coupling precision
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 high-power blue laser diode systems overcome the limitations of IR systems by achieving efficient materials processing, including welding, cutting, and 3D printing, with improved build volume and speed, and are capable of producing multi-kW laser beams with narrow spectral bandwidths for precise applications.
Implementation Method 1
fiber-coupled blue laser diode arrays
Implementation Method 2
volume Bragg gratings
Implementation Method 3
dichroic filters
Implementation Method 4
pumping Raman fiber lasers
Data Source
AI summary
The invention may be embodied in other forms than those specifically disclosed herein without departing from itMulti-kW-class blue (400-495 nm) fiber-delivered lasers and module configurations. In embodiments, the lasers propagate laser beams having beam parameter products of <5 mm*mrad, which are used in materials processing, welding and pumping a Raman laser. In an embodiment the laser system is an integration of fiber-coupled modules, which are in turn made up of submodules. An embodiment has sub-modules having a plurality of lensed blue semiconductor gain chips with low reflectivity front facets. These are locked in wavelength with a wavelength spread of <1 nm by using volume Bragg gratings in an external cavity configuration. An embodiment has modules having of a plurality of submodules, which are combined through wavelength multiplexing with a bandwidth of <10 nm, followed by polarization beam combining. The output of each module is fiber-coupled into a low NA fiber. In an embodiment a kW-level blue laser system is realized by fiber bundling and combining multiple modules into a single output fiber.