Flowerlike patterns generated by a laser beam transmitted through a rubidium cell with single feedback mirror

Abstract
A spatial instability is observed when a laser beam at 795 nm is transmitted through a rubidium cell with single plane feedback mirror. The emitted beams have patterns looking like flowers. The dependence of the number of petals in the pattern with the distance between the cell and the mirror is studied and interpreted using an expansion of the instability in Laguerre-Gauss modes. This experiment shows the influence of the saturation of the nonlinearity in the pattern selection.