Optival Near-Field Interaction of Atoms with Dielectric Sarface

本文从理论和实验两个方面研究了近介质表面光学近场中光子-原子相互作用的动力学特性，指出亚波长介质材料光学近场的形状依赖特性是光学近场显微镜超高分辨率的根源，它反映了光学近场中光子-原子相互作用的动力学变量。空间位移和旋转下的局域对称性决定了近场光相互作用中的守恒量--赝动量和赝角动量，通过建立一种基于矢量场角谱表示的光学近场和光学近场相互作用的新的理论处理方法，对这一特性进行了理论分析.这为发展包括光学近场显微镜分辨率问题在内的一般光学近场理论提供了非常有用的基础。 ...更多信息 利用一种新发展的激光光谱技术，利用原子超精细态的光泵浦，在实验上证实了超精细场的存在。实验结果表明，与自由空间共振光子吸收相比，铯原子与倏逝波共振相互作用的穿透深度较短，赝动量的转移量较大，这与理论预测吻合较好，进一步开展这方面的实验研究，需要克服近场激光光谱中原子序数小和自旋敏感的问题。我们发展了一种利用倏逝波的双光子电离光谱，并成功地观察到了Cs原子束在介质表面附近的超精细光谱。利用高频率控制的AlGaAs激光器和电离蓝光激光器产生Cs离子，用二次电子倍增器和光子计数系统对Cs离子进行超高灵敏度探测。这为研究光学近场的偏振行为或自旋态以及操纵原子自旋态和纳米尺度物质电子态的实验研究提供了一个非常有用的工具。少

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