Scaling laser beams to higher output power levels requires combining the outputs of many individual lasers through a beam combining process. One method is known as spectral beam combining where many lasers each with a different narrow band spectral output are combined through reflective grating optics. However, this method is limited by the laser damage thresholds of the reflective grating optics. Mitigating laser damage threshold limitations requires large beam diameters and large optics which in turn drive up system size, weight and cost. There is a need to be able to combine many lasers more compactly and at lower cost.
LLNL has designed and demonstrated a novel transmission Spectral Beam Combining grating optic assembly with megawatt power handling capabilities. The design consists of a monolithic structure with an input transform optic and an output transmission grating. The design features LLNL’s proven compact, lightweight Spectral Channels Splicer architecture to combine adjacent spectral channels of arbitrary spectral widths.
The SCS is an array of optical elements whose individual width along the output grating dispersion axis have spectral widths defining channels, replacing the narrow band SBC emitters. Each Channel Optical Element (COE) takes the place of many adjacent narrow band emitters. Each COE accommodates a wide spectrum and tilting each channel optical path separates each channels input optical systems.
LLNL’s compact, lightweight apparatus for combining outputs of high energy lasers has several advantages over other approaches:
- Employs simple, reliable, modular architecture,
- Free of single point failure mechanisms,
- Employs commercial-off-the-shelf (COTS) low-cost fiber laser systems,
- Enables realizing compact, scalable systems in less than 10% the volume of current designs,
- Low overall system size, weight and power (SWAP).
- High energy laser systems
- High power industrial materials processing
- High energy laser spectral beam combining
Current stage of technology development: TRL 2
LLNL has filed for patent protection on this invention.