EXACT GREENS-FUNCTION FOR A CLASS OF PARAMETRIC-INSTABILITIES

The spatiotemporal evolution of stimulated Brillouin scattering and st imulated Raman scattering is studied analytically without recourse to the envelope approximation on the time scale of the plasma oscillation s. In their regimes of validity, the standard approximate Green's func tions for weak coupling and strong coupling describe the growth of the scattered light wave accurately. However, in the transition period be tween the two regimes, which can be a significant fraction of the dura tion of an experiment, the approximate solutions cannot be applied and the exact Green's function, which is valid for all times, is required . (C) 1998 American Institute of Physics. [S1070-664X(98)04312-2].