Optical dipole trap using a Fabry–Perot interferometer as a power buildup cavity

We construct an optical dipole trap using a Fabry–Perot interferometer as a power buildup cavity. Large power enhancement allows us to produce 9 mK deep potential wells with 48 µm spot size and 100 nm detuning from the rubidium D 1 resonance. The optical trap is loaded from a dark-spot magneto-optical trap which, in turn, is loaded from a low-velocity intense source of 85 Rb atoms. Under typical experimental conditions, there are 1.4 × 10 6 atoms in 2000 antinodes of the optical trap. Average atom density is 1.1 × 10 12 cm -3 . The number of trapped atoms is limited by the atom density, or trapping volume. The standing-wave configuration with tight longitudinal confinement has much smaller trapping volume compared with the equivalent travelling wave. A method for converting the trap to a travelling wave-like configuration using phase modulation is proposed.