FROM their use in technologies as simple as laser pointers to as complex as the National Ignition Facility, lasers have a wide range of applications in today’s world. Typically, laser-based devices rely on a single-output system, where the laser is produced from a solitary source and then amplified through sophisticated optics. In contrast, spectral beam combining (SBC) is a technique in which several individual beams with nonoverlapping optical spectra are combined to produce one high-power beam.
SBC systems generally use fiber lasers as the beam source because they are robust, efficient, and compact. Fiber lasers can also operate over a range of wavelengths. The lasers are coupled with a dispersive optical element, such as a diffractive grating or prism, which can deflect incident beams according to each beam’s wavelength and spatially overlap the beams so that they propagate in the same direction. However, these optical elements typically cannot handle the higher power needed for advanced material processing applications, scientific research, and certain military purposes.
An R&D 100 Award–winning team comprising researchers from Lawrence Livermore, Lockheed Martin, and Advanced Thin Films, Inc., has developed the extreme-power, ultralow-loss, dispersive element (EXUDE) for adapting SBC to high-power applications. EXUDE integrates improved optical coatings, a novel surface-relief grating structure, and innovative fabrication and processing techniques to enable an electrically efficient, near-diffraction-limited multikilowatt SBC laser system.