Abstract

We propose and demonstrate a new blue-detuned dipole trap for atoms. A dark ellipsoid completely surrounded by light is created by passing the center of a Gaussian 1 watt Ti-Sapphire laser beam through a holographic phase plate, followed by a focusing lens. Destructive interference creates in the focal plane and along the optical axis a dark region with a diameter of ~50 μm and length of ~1 mm (Fig. 1). This trap was loaded with cold Rubidium atoms released from a Magneto Optical Trap. At a detuning of +1 nm from resonance (with the D₂ line), ~10⁵ atoms are loaded into the trap. Trap length was measured to be ~1 mm, and by time-of-flight techniques the atoms temperature was measured to be 25 μK.

© 1998 IEEE