This paper studies gratings engraved in multilayer dielectric stacks for ultra high intensity laser compressors application. We design various grating profiles with high reflected efficiencies for 1780 l/mm multilayer dielectric gratings (MLD). Each grating is defined to exhibit a different electric field maximum value in the pillars of the grating. A damage testing facility operating at 1.053 mum, 500 fs pulse duration is used to damage test the parts manufactured from these designs. It is evidenced that for fixed incident angle and materials the damage of the grating is directly related to the electric field intensity maximum in the material, which depends on the groove profile. Laser induced damage thresholds of 5 J/ cm(2) are experimentally reached with very high and uniform efficiencies.

In the range of nanosecond pulse lengths, the mechanisms of surface laser damage to dielectric materials are still unclear. A large amount of experimental and theoretical work has been performed over recent years. In order to test theoretical predictions and compare experimental results, reproducibility is essential whatever the beam parameters and experimental conditions. The rasterscan procedure, previously developed to test large components, is an efficient method that allows measuring extremely low surface damage site density (until 0.01 site/cm2 for large optics). In this paper, we show that by suitable data reduction, error bar calculation, and attention paid to beam analysis, laser-induced surface damage density of fused silica optics can be measured with high accuracy and repeatability in the range of pulse durations from 2 to 16 ns. This procedure provides a straightforward means of comparing the experimental results obtained from several facilities using different lasers.

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