A. Gahl et al., SELF-INDUCED PLANAR AND CYLINDRICAL SPLITTING OF A LASER-BEAM IN SODIUM VAPOR, Physical review. A, 50(2), 1994, pp. 180000917-180000920
An almost linearly polarized laser beam focused into a sodium vapor ce
ll may split into different patterns ranging from two spots to a spot
and a ring of opposite circular polarization. The patterns are control
led by static magnetic fields of the order of the earth's field. The b
ehavior is explained, allowing for a longitudinal component of the die
lectric polarization in the paraxial wave equation. Numerical results
reveal the delicate balance between light shift, influence of the magn
etic field, and the creation of ground-state orientation by the compet
ing polarization components.