Phase conjugation due to stimulated Brillouin-scattering in a loop system with a mirror

An investigation was made of stimulated Brillouin scattering (STBS) in a parametric resonator with a self-intersecting pump beam and a mirror which returned the beam to a nonlinear medium. The results indicated that the threshold of STBS, excited by the phase-conjugation pump wave, could be halved compared with the usual loop variant. A suitable alignment of the mirror made it possible to return the pump radiation to the active medium of the exciting laser which acted as the pump source.