Optival Near-Field Interaction of Atoms with Dielectric Sarface

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In this work, dynamics of photon-atom interactions in optical near-field near dielectric surface are studied both theoretically and experimentally .Shape-dependent character of optical near-field of subwavelength-seze dielectric matters is the origin of ultra-high resolution of optical near-field microscopes, which reflects on the dynamical variables in photon-atom interactions in optical near-field. Local symmetries under spatial displacement and rotation determine the conserved quantities, pseudo-momentum and pseudo-angular momentum, during near-field optical interacion.Thse characteristics are analyzed theoretically by developing a novel theoretical treatment of optical near-field and optical near-field interaction based on angular spectrum representation of vector field. This provides a very useful basis in development of general optical near-field theory including resolution problems in optical near-field microscopy.In the experimental work of this project, the pseudo-momentum tra … More nsfer has been demonstrated experimentally using a newly deve1oped laser spectroscopy technique with optical pumping of atomic hyperfine state. The results of resonant interaction of Cs atoms with evanescent waves show good agreement with theoretical prediction about short penetration depth and transfer of pseudomomentum which is larger than that in the case of resonant photon absorption in free space.For further development of experimental study in this direction, we should overcome the problem of small atomic number and spin sensitivity in near-field laser spectroscopy of atoms. We have developed a two-photon ionization spectroscopy using evanescent wave and succeeded to observe the hyperfine spectra of Cs atomic beam near a dielectric surface. A combination of highly frequency-controlled AlGaAs laser and ionizing blue-laser produces Cs ions which are detected by using secondary-electron multiplier and photon-counting system with an ultra-high sensitivity. This provides a very usuful tool especially for experimental studies taking account of the polarization behavior or spin state of optical near-field as well as aplications of manipulating spin states of atoms and electronic state of nanometer size matter. Less