SPATIAL SEPARATION OF CIRCULARLY-POLARIZED LASER-BEAMS IN SODIUM VAPOR

We observed experimentally that a superposition of two co-propagating left and right hand circularly polarized laser beams is spatially unst able during propagation through a vapor of sodium atoms containing arg on buffer gas. A small spatial asymmetry between the two input beams l eads to their separation into two pure circularly polarized output bea ms. However a single linearly polarized input beam was found to be spa tially stable. Our theoretical results from Maxwell-Bloch propagation calculations using both modal expansion and direct partial differentia l equation solution methods are in good agreement with the experiments . The splitting mechanism can be explained in simple terms as consisti ng of an absorption and dispersion dominated initial part and a diffra ction dominated final part.