Lithium yttrium fluoride (LiYF4: Nd3+) – promising laser material for picosecond spectroscopy

An investigation was made of passive mode locking in lasers with active media in the form of anisotropic fluorides LiYF₄ and LiLuF₄ activated with Nd³⁺ ions. Selection of the optical dynamics of laser pulses (due to the ⁴F_3/2→⁴I_11/2 transition) and use of Soviet dyes characterized by different bleaching intensities and different relaxation times ensured a minimum duration of ~ 6 ps with an energy of 10 mJ per pulse.