Diode-laser production of collimated slow cold potassium beams and crossover resonances

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Abstract
We describe the results of three sets of experiments to investigate producing cold slow collimated potassium atoms for applications with no access available for the introduction of counterpropagating laser light along the exiting atomic beam’s axis. Velocity profiles are obtained via fluorescence from D1 excitation at perpendicular and nearly parallel incidence by a probe laser. Spatial profiles of both the cold- and residual hot-beam components are measured with a position-scanned hot-wire detector. Velocity-component holes and decelerated cold components are observed, along with direct evidence of perpendicular heating of the cold components. A first set of experiments uses a variant of conventional chirp cooling and/or hole burning. Light is introduced by a heated inclined mirror, while atoms exit through a slit in the mirror. Loss of intensity at low velocity is observed and discussed. A second set of experiments investigates velocity-selective optical-pumping crossover resonances that occur near the mirror, where the incident and reflected beams overlap for several alternative geometries. A third set of experiments investigates cold-beam production using laser-induced velocity selection and deflection. It provides a higher cold-atom intensity, along with the means to perform high-resolution spectroscopy.