Improving the beam quality of solid-state systems using both outside and inside cavity devices with variable optical characteristics along the cross section (original) (raw)

This paper presents the results of application to different laser installations of soft or apodized apertures (AA) [1-3]* with smooth transmission profiles decreasing from center to edges. Two types of AA, which were made of CaF~:Pr crystals, have been used: induced absorption (IA) AM and photooxidation (PhO) AA. The-3-45-mm-diameter IA and PhO AA with smooth monotonic fiat-top profiles have been used in 1.06-#m laser amplifier systems to suppress hard-edge Fresnel diffraction rings in beam cross section and to increase the second harmonic conversion efficiency. The ~3-4-mm-diameter PhO AA with bell-like transmission profiles were placed inside the 2.94-pm and 1.06-lzm resonators of master oscillators. The tendency of the output energy to increase by 1.3-1.8 times and the decrease in beam divergence in single-mode lasing as compared with a hard-edge aperture have been observed in the experiments described below.