Long-distance channeling of cold atoms exiting a 2D magneto-optical trap by a Laguerre-Gaussian laser beam.

Using a blue-detuned laser, shaped into a nearly Laguerre-Gaussian (LG) donut mode, we channel atoms exiting a two-dimensional magneto-optical trap (2D-MOT) over a 30 cm distance. Compared to a freely propagating beam, the atomic flux (∼10(10) at/s) is conserved whereas the divergence is reduced from 40 to 3 mrad. So, 30 cm far the 2D-MOT exit, the atomic beam has a 1 mm diameter and the atomic density is increased by a factor of ∼200. The LG-channeled-2D-MOT has been studied versus the order of the LG mode (from 2 to 10) and versus the laser-atom frequency detuning (from 2 to 120 GHz).