Neodymium-doped yttrium aluminate laser with a pulse repetition frequency of 12.5 Hz and efficient second and third harmonic generation

A pulse-periodic yttrium aluminate (YAlO₃:Nd³⁺) laser consisting of an oscillator and two amplifiers is described. At a fixed pulse repetition frequency of 12.5 Hz, the first harmonic was converted to the second with a 30% efficiency and to the third with a 6% conversion efficiency using KDP crystals. This efficiency was achieved by selecting an unstable resonator configuration in the oscillator and compensating for the angular divergence of the radiation using an adjustable telescope.