Atom guidance in the TE$_{01}$ donut mode of a large-core hollow fiber

We report on our progress towards low-light-level nonlinear optics experiments by optically guiding atoms in the TE$_{01}$ donut mode of a hollow fiber. Atoms are transported over 12 cm from a ``source'' magneto-optical trap (MOT) through a 100-$\mu$m-diameter hollow fiber and are recaptured by a ``collection'' MOT situated directly below the fiber. For red-detuned guiding, we compare the guiding efficiency between the fundamental (Gaussian-like) mode and this donut mode, which has a larger guiding area but lower peak intensity. We also discuss our progress in transporting atoms in the dark core of this mode using blue-detuned light, which has more stringent constraints to atom guidance compared to red-detuned light.