NONLINEAR RING STRUCTURES IN FORWARD SCATTERING OF RESONANT MONOCHROMATIC LASER-RADIATION

We present experimental and theoretical investigations of a Gaussian l aser beam interacting with Zeeman-tuned J=1-->J=0 atomic systems. In o ur experiment a single-mode cw dye-laser beam traverses a neon dischar ge in a longitudinal magnetic field. The excited neon transitions used for these studies are 1s4(J=1,g=1.464)-->2p3(J=0) and 1s2(J=1,g=1.034 )-->2p1(J=0). In the laser-induced forward-scattered light, dark and b right ring-shaped structures are observed. The ring structures are inv estigated as a function of the magnetic detuning of the m = +/-1 suble vels and as a function of the laser-beam power. We find that the line shapes of the spectra, i.e., the forward-scattered light intensities a s a function of the magnetic detuning, are sensitive to the transverse intensity distribution of the laser beam. Analytical expressions base d on a semiclassical theory are derived and the calculated results on the ring structures and the spectra are compared with the experimental results. Good agreement between the calculated and the experimental r esults are obtained only when the transverse effects are taken into ac count.