Doughnut mode magneto-optical trap

Abstract

We have developed a magneto-optical trap that is well suited for high-resolution spectroscopy. It uses a combination of doughnut mode (Laguerre–Gaussian TEM₀₁) and TEM₀₀ cooling beams rather than the usual TEM₀₀ cooling beams. This configuration allows us to tailor the intensity distribution within the magneto-optical trap such that the atoms are cooled from the background vapor by the intense TEM₀₁ beams and then trapped by the weak TEM₀₀ beams. This greatly reduces the magnitude of the ac-Stark shift and the line broadening induced by the cooling lasers, allowing high-resolution spectroscopy to be performed in the presence of the cooling beams.