Improved damage threshold and diffraction efficiency of gratings for ultra-bright lasers in sub-picosecond regime

Summary form only given. For the last 15 years, diffraction gratings have been the key critical components of the chirped pulse amplification (CPA) technique. They can introduce a large dispersion on an optical short pulse without propagating through a dispersive medium. However, their limited damage threshold has led to limited compressed energy. Furthermore, all present diffraction gratings used in CPA laser chains have a limited diffraction efficiency (typically 60% in it four-´pass scheme). Current diffraction gratings are made by etching a silicate substrate before evaporating a thin gold layer on the top. This means that the diffraction occurs at the surface. The energy is thus concentrated in a very thin layer. Consequently, a way to improve the damage threshold is to let the electro-magnetic field diffract in the material bulk, for instance, in a multi-layer dielectric material. The grooves of the diffraction gratings can be produced by ion-etching dielectric coated mirrors.