Nonlinear distortion of laser radiation in haze

Experimental results are presented concerning the dynamics of the thermal nonlinearity of the refractive index of a gaseous medium with an absorbing aerosol (soot suspended in air) under the effect of intense laser radiation as well as concerning the contribution of halo scattering to the total attenuation. Results are presented for different values of laser power density and initial optical thickness: 4.4 J/sq cm and 0.22 in the first case and 2 J/sq cm and 1.8 in the second case. It is shown that absorption constitutes about 20-30 percent of the total attenuation. The experimental results are interpreted in the framework of a theoretical analysis which assumes the additive contribution of halo effects to the scattering.