INFLUENCE OF TRANSVERSE EFFECTS ON SELF-INDUCED POLARIZATION CHANGES IN AN ISOTROPIC KERR MEDIUM

Allowing for an isotropic optical nonlinearity of third order, we deri ve approximate Gaussian solutions of the paraxial wave equation. They describe a monochromatic elliptically polarized light signal of finite extension both in space and in time. In contrast to plant-wave result s, the state of polarization is found to be strongly nonuniform in the transverse direction. Both the orientation and the shape of tile pola rization ellipse are not conserved. For low intensities, parameters me asuring tile induced optical activity depend on the intensity quadrati cally instead of linearly. For high intensities, saturation sets in. I t is argued that by means of nonlinear ellipsometry one can evaluate t wo tensor components, namely, Re chi(xyyx)((3)) and Re chi(xxxx)((3)). Upon taking into account transverse as well as temporal effects, the magnitude of these components may decrease by a factor of 10. (C) 1997 Optical Society of America.