Optimal geometry of atom funnels with surface-plasmon enhanced evanescent light field

• We enhanced evanescent light field by surface-plasmon resonance for atom funnels.
• The field enhancement was evaluated theoretically and experimentally.
• We modeled polyhedral-pyramid and cone shape funnels coated with a gold thin film.
• Flux intensity of atomic beam was evaluated by conducting Monte Carlo simulations.

We enhance the evanescent light field for funneling cold atoms by surface-plasmon resonance. When a 780.2-nm light beam is incident on a glass–gold interface from the glass side at an angle of 44.6°, the intensity rises 14.4-fold for p  -polarization and 7.2-fold for circular polarization compared to the case with total-internal reflection. Then, we evaluate the flux intensity of a resultant Rb atomic beam for three funnel shapes of a cone, a quadrangular pyramid, and a triangular pyramid. Monte Carlo simulations show that the flux intensity exceeds 1atom/nm2s when the outlet diameter is smaller than 10μm. In particular, the conical funnel yields the highest flux intensity for circular polarization. Also, there is an optimal outside diameter of a hollow light beam generating evanescent light field for a given incident power. A prototype conical funnel is fabricated with a 3D printer.