Long-Range Interactions between cw Self-Focused Laser Beams in an Atomic Vapor

Abstract

We have observed that circularly polarized laser beams of opposite (equal) polarizations in an alkali vapor repel (attract) each other for laser frequencies on the high-frequency wing of the $D_1$ line. Our experiments indicate that these long-range noncontact interactions are mediated by the exchange of polarized atoms between the beams. The repulsion between ${\sigma }_{+}$ and ${\sigma }_{-}$ beams leads to the breakup of a linearly polarized laser beam into two coherent beams of opposite circular polarization.