High damage threshold and efficiency gold coated gratings for laser pulse compression systems

Abstract
Methods for essential increase in the damage threshold of conventional gold coated diffraction gratings are considered. An increase of the golden coating thickness up to 400 nm, applied by magnetron sputtering allows one to obtain a four-fold increase in the damage threshold with a high diffraction efficiency (93%) conserved throughout the working spectral range. An additional two-fold increase in the damage threshold is achieved by application of two couples of dielectric layers of HfO₂ and SiO₂. Yet, high values of diffraction efficiency are realized in a long wavelength spectral range, where the ratio of radiation wavelength incident on a grating to its period is larger than 1.5. In a short-wave spectral range the value of incidence with additional dielectric layers decreases faster than diffraction efficiency for gold coated gratings. This is the result of a resonance nature of interference. For these reasons to make the gratings operation in the spectral region ( ) more effective the gratings with number of grooves N 1500 mm ^{- 1} are to be used.