HIGH-EFFICIENCY METALLIC DIFFRACTION GRATINGS FOR LASER APPLICATIONS

The design and fabrication of large-area, high-efficiency metallic gra tings for use in high-power laser systems is described. The gratings e xhibit a diffraction efficiency in excess of 95% in the m = -1 order ( Littrow mount) and have a high threshold for laser damage. Computation s and experimental measurements are presented that illustrate the effe ct of grating shape and polarization on efficiency. A simple theory fo r optical damage to metallic diffraction gratings is developed and com pared with experimental measurements of the laser-damage threshold ove r the pulse range from 400 fs to > 1 ns.