Large-volume single-beam dark optical trap for atoms using binary phase elements

A novel method to trap ultracold atoms in a single-beam, dark optical dipole trap, which uses a binary phase element, is proposed and demonstrated. The length and the width of this trap are independently controlled to enable a larger volume, a more symmetric shape, and a higher loading efficiency. More than 10(6) rubidium atoms were loaded into the trap at a trapping laser detuning of 0.1-10 nm above the atomic transition. (C) 2000 Optical Society of America [S0740-3224(00)03406-8].