Abstract

A new method is proposed^[1] for laser cooling atoms with Doppler shifts an order of magnitude larger than the homogeneous linewidth of the atomic transition. This allows one to stop a substantial fraction of an atomic beam without chirping the laser or Zeeman tuning the atoms. Stimulated cooling has been shown in previous work^[2] to lead to velocity damping rates that can be several orders of magnitude greater than spontaneous force cooling. In present method, this large damping rate is exchanged for a broad bandwidth by crossing two traveling waves at an oblique angle 2θ so that a dipole force potential well is created with a wavelength λ/sin θ which is much greater than that of either traveling wave. See Fig. 1. The resulting stimulated cooling forces may be called “broadband” since the region of linear velocity damping is increased by a factor 1/sin θ which may be a factor 10 or more. In sodium the capture velocity can be as high as ± 120 m/s, which permits stopping 0.1% of the flux of a 500 K atomic sodium beam in a distance of 300 microns and a time of a few microseconds. This is more than 100 times faster than current methods.

© 1992 IQEC