The input pulse of the laser PEARL with energy of 18 J and pulse duration of about 60 fs was compressed to 10 fs after passage through a 4-mm-thick KDP crystal and reflection at two chirped mirrors with sum dispersion of −200 fs2. The experiments were performed for the В-integral values from 5 to 19 without visible damage to the optical elements, which indicates that small-scale self-focusing is not a significant issue. It was shown that, by virtue of the low dispersion of the group velocity, the KDP crystal has some advantages over silica: a larger pulse compression coefficient, especially at a small value of the В-integral (B = 5, …, 9), lower absolute values of chirped mirror dispersion, and also a possibility to control the magnitude of nonlinearity and dispersion by changing crystal orientation.
