“…Crystals of borate family, such as 2 4 α-BaB O , 2 4 β-BaB O , 2 4 7 Li B O , 4 7 PbB O and 4 7 SrB O , are known as efficient materials for nonlinear optical applications (see [1][2][3][4][5][6]). A wide range of their optical transparency, particularly in the ultraviolet (UV) spectral region [7][8][9][10][11] (up to 125 nm for 4 7 SrB O [10, 11]), and a high level of optical damage threshold [11,12] make them one of the best materials for operation of short-wavelength high-power laser radiation.…”