Abstract

We describe a relatively large volume dipole laser trap for the confinement of sodium atoms. Two counterpropagating beams, tuned below resonance, with foci separated by approximately one con focal parameter, provide radial confinement via the dipole force and axial confinement by balancing the radiation pressures of the two beams.¹ Identical circular polarization for both beams prevents optical pumping and serves to maintain a two-state system. Alternation of the two beams² is necessary to avoid the effects of standing-wave heating. Additionally, the trapping cycle is alternated with a Doppler cooling cycle² to achieve low temperatures and long confinement times. Trapping beams of 100 mW focused to 50-μm spot radii and detuned ~2 GHz below the F = 2 to F′= 3 transition of the D₂ line provide a well depth of 50 mK and a confinement volume of 10^-4 cm³. Analysis of atomic motion and escape mechanisms as well as progress toward the experimental realization of this trap is presented.

© 1986 Optical Society of America