Characteristics of YAG:Nd$^{3+}$ lasers passively $Q$ switched by LiF crystals containing color centers

An investigation was made of the lasing characteristics of YAG:Nd$^{3+}$ lasers passively $Q$ switched by LiF crystals containing $F_2^-$ centers. It was observed that these switches smoothed the diffraction (annular) structure of the radiation in the near field and result in spontaneous linear polarization. The lasing spectrum consisted of one or two longitudinal modes, the giant pulse energy in the single-mode regime was 25 mJ, and the pulse duration was 20–30 nsec. It was established that the contribution made by the LiF samples to the total thermal deformation of the resonator was negligible, which helped to keep the lasing characteristics constant when the pulse repetition frequency was increased.