Fourth harmonic generation of a large-aperture Nd:glass laser

Basic properties of the fourth harmonic conversion of 1.053-μm laser radiation with KDP crystals are experimentally determined. Optimization of crystal thickness, based on numerical simulations is discussed. A large aperture conversion cell combining second and fourth harmonic generators has been designed. Overall conversion efficiencies (ω → 4ω) in excess of 40% have been achieved for incident laser intensities between 1 and 2.5 GW/cm2.