Single-mode YAG:Nd laser with a stimulated Brillouin scattering mirror and conversion of radiation to the second and fourth harmonics

The development of a YAG:Nd laser having the following output radiation parameters is reported: pulse energy 1.5 J, divergence 1.5 times the diffraction limit, pulse duration 25 ns, and pulse repetition frequency 25 Hz. Conversion to the second harmonic was achieved with an efficiency of 50–70% and conversion from the second to the fourth harmonics was achieved with an efficiency of 35 %. Stimulated Brillouin backscattering of the fourth harmonic was also observed.