Transverse-Pattern Formation for Counterpropagating Laser Beams in Rubidium Vapour

Abstract

An instability is observed when the intensity of two counterpropagating beams nearly resonant with the 5S1/2 → 5P1/2 transition of rubidium exceeds a threshold value. The instability manifests itself as a coherent emission on the polarization orthogonal to that of the incident beam with various spatial structures, depending on laser intensity and frequency. Bifurcation diagrams for the intensity of this instability with the associated transverse-pattern evolution are presented.