DYNAMICS OF LASER-BEAM SWITCHING IN SODIUM VAPOR

The interaction of left- and right-hand circularly polarized narrow-ba nd cw laser beams that copropagate through sodium vapor and are tuned to the homogeneously broadened D1 transition can lead to the mutual ex tinction of both beams. Such beam switching is caused by an intensity- and polarization-dependent refractive index due to optical pumping ev en at low intensities. The dynamics of beam switching is investigated experimentally and explained qualitatively by the conventional J = 1/2 to J = 1/2 transition model. The accurate quantitative description, h owever, is only achieved by an extended model comprising hyperfine gro und states in spite of homogeneous line broadening by argon buffer gas , which is larger than the hyperfine splitting.