EXPERIMENTAL-STUDY OF THE PROPAGATION OF AN APERTURED HIGH-INTENSITY LASER-BEAM IN KERR-ACTIVE CS2

Transverse pattern formation along the propagation in Kerr-active CS2 of a circularly and an elliptically apertured high-intensity input bea m is studied. Observation is made of the modification in the Fresnel d iffraction pattern as a function of the input beam power and the propa gation distance. In addition to the well defined ring patterns, at hig h powers these rings break up into several spots. Also, a thermal-indu ced nonlinearity was observed to affect the dynamics of the pattern fo rmation. Both forward stimulated Raman scattering (SRS) and backward s timulated Brillouin scattering were observed to occur during the propa gation of the beam along the CS2 cell. An unexpected pattern of fringe s was always observed in the Stokes components of the SRS.