Use of a T-shaped resonator and a stimulated Brillouin scattering mirror to improve the directionality of laser radiation

An experimental investigation was made of a YAG:Nd laser with a four-mirror resonator and an external stimulated Brillouin scattering (STBS) mirror. Under conditions of passive Q switching we studied the radiation characteristics as a function of the parameters of a three-mirror interferometer–reflector and the rate of pumping of the active element. It was found that the highest radiation brightness was achieved for an unstable interferometer–reflector. The laser pulse energy increased when the radiation reflected from the STBS mirror was in resonance with the longitudinal modes of the interferometer–reflector.