INFLUENCE OF THERMAL DEFOCUSING ON THE QUALITY OF PHASE-CONJUGATION OF GAUSSIAN BEAMS BY STIMULATED BRILLOUIN-SCATTERING

A numerical investigation is reported of the influence of the thermal self-interaction of a Gaussian pump beam on the quality of phase conju gation by stimulated Brillouin scattering (SBS). A laser pulse is assu med to be sufficiently long to apply the equalised pressure approximat ion in calculating the acoustic field. All the calculations are carrie d out in a three-dimensional formulation for focused beams making use of an approximation linear in respect of the pump intensity. It is con firmed that the growth of thermal perturbations increases the SBS thre shold and lowers the phase conjugation quality. A comparison of the ca lculated and published experimental results shows that they are in sat isfactory quantitative agreement.