An efficient numerical 3-D model of transient stimulated Brillouin scatteri
ng (SBS) is reported. The model is used to examine the effects of transient
phenomena on the efficiency of phase conjugation by SBS and the mode struc
ture of the Stokes and pump pulse inside the SBS cell. The effect of parame
ters such as phonon lifetime, input pulse shape and input energy on the tra
nsient fidelity of SBS is investigated. A new transient phenomenon which ca
uses SBS fidelity degradation at high focal intensity (short Rayleigh range
) is examined.