Phase conjugation in stimulated Brillouin scattering under thermal self-interaction conditions

An analysis is made of the influence of thermal self-interaction of long pulses (of duration greater than 100 μs) on the efficiency of phase conjugation in stimulated Brillouin scattering. It is found that thermal self-defocusing of the pump radiation results in a mismatch between the Stokes wave formed at the constriction and the pump wave during propagation toward the entry end of the cell. This increases the divergence of the Stokes beam and reduces the phase conjugation coefficient. A reduction in the peak pump power in the constriction results in strong attenuation of the Stokes output beam.