Nano-optics: Atoms in the Near Field

Abstract

The classical scientific “best seller” by M. Born and E. Wolf already contained some elements of nano-optics (the near-field Mie scattering), though this domain of science has only recently started developing in connection with the vigorous development of nanotechnology. The optical near field differs substantially from the optical far field usually used in optical systems, measuring much more than the wavelength of light. The optical near field arises near structures of subwavelength size or near boundaries. The word “near” always means a subwavelength distance. In other words, the near field is as if “tied” to these subwavelength structures or boundaries; i.e., it does not propagate and contributes nothing to the far field formed at distances much longer than the wavelength of light. The optical near field localized within a subwavelength region forms the basis of nanooptics, a part of nanotechnology. The nanolocalization of an optical field makes its intensity highly nonuniform in space. The strong spatial inhomogeneity of the optical near field, first, makes it possible to control the spectral characteristics of atoms placed in it (atoms near nanostructures); and second, gives rise to a gradient force that enables one to control the motion of the atoms and forms the basis of atom optics. Finally, the optical near field localized near metal nanostructures can interact in a resonance fashion with plasmons whose frequency is close to that of the optical field, the plasmons themselves being of a subwavelength size. This interaction highly enhances the intensity of the localized field and forms the basis of plasmon nano-optics and entirely new effects, such as the extraordinary optical transmission through subwavelength hole arrays (the Ebbesen effect). In this chapter, we consider but a single avenue of inquiry in nano-optics that is associated with both the control of the spectral properties of atoms near nanostructures and the motion of atoms in the optical near field.