Spectroscopy of near-surface atoms using an optical nanofiber

We investigate the laser induced fluorescence spectra of laser-cooled Cesium atoms in the vicinity of a silica nanofiber by observing the fluorescence photons through the guided-modes. The observed excitation spectra of such near-surface atoms reveal drastic difference from free-space atom and show signatures of atom–surface bound states. We experimentally demonstrate that the spectrum lineshape and hence the loading into such surface bound states can be controlled by changing the surface conditions. The measured emission spectra, under the controlled surface conditions, further clarify the behavior of free- and bound-atoms. We discuss the possible roles of adsorption and desorption of atoms in controlling the surface conditions.