Velocities of speckles in a smoothed laser beam propagating in a plasma

By means of three-dimensional simulations, the paraxial propagation of a la ser beam in a nonlinear plasma modeled by ion-acoustic waves is examined. T he beam speckles are smoothed by a one-dimensional transverse spectral disp ersion technique. In the case of weak smoothing and when the incident speck le velocity is subsonic, the propagation in the plasma is found to exhibit an asymptotic speckle velocity and to enhance filamentation. With contrary conditions, it is found to reduce simply the speckle velocity. (C) 2001 Ame rican Institute of Physics.