Nonlinear beam shaping in an anisotropic magneto-optical trap

We report on nonlinear beam shaping obtained in an anisotropic magneto-optical trap (MOT). In the anisotropic MOT, atoms are cooled in all directions but only trapped in the radial direction, thus producing a pencil-shaped volume of cold atoms. This sub-Doppler cooled collection of atoms can be made several centimeters long with optical depths (OD; Iout/Iin=exp(-OD)) on the order of 50, and has an approximately Gaussian radial density distribution. This allows for the observation of beam shaping in the regime where the medium must be considered as optically thick and diffraction during the interaction must be considered.