Multireflection of cold atoms in a near-field optical funnel

Multireflection of cold Rb atoms occurs inside a reversed triangular hollow prism with a blue-detuned optical near-field. We examine it with a probe light beam, using the frequency detuning and the diameter of an excitation light beam as parameters. In the first bounce, the number density of the reflected atoms reaches a maximum of 106 atom/cm3 at a blue detuning of 0.7 GHz when the beam diameter is 4 mm. The Rb atoms repeat reflection with a period of about 15 ms and an efficiency of 83% per bounce. A cold Rb atomic beam with a high flux of 4 × 1011 atom/(cm2·s) can be generated through a near-field optical funnel composed of the prism.