Laser spectroscopy of atoms guided by evanescent waves in micron-sized hollow optical fibers

We report the first laser spectroscopic experiments on the Rb beam guided by blue-detuned evanescent waves in micron-sized hollow fibers. The two-step photoionization spectra show the long-range dispersive properties of dipole interaction between guided atoms and evanescent waves. A large enhancement factor of 20 in in the transmitted atomic flux is obtained at optimal conditions and the total guidance efficiency is estimated to be above 40%. The state- and species-selective guide with proper frequency detunings of the guide laser realizes in-line spatial separation of two stable Rb isotopes.