We have improved the optical characteristics of aluminum-coated fiber probes used in near-field scanning optical microscopy by milling with a focused ion beam. This treatment produces a flat-end face free of aluminum grains, containing a well-defined circularly-symmetric aperture with controllable diameter down to 20 nm. The polarization behavior of the tips is circularly symmetric with a polarization ratio exceeding 1:100. The improved imaging characteristics are demonstrated by measuring single molecule fluorescence. Count rates increase more than one order of magnitude over unmodified probes, and the molecule images map a spatial electric field distribution of the aperture in agreement with calculations.

Abstract-Optical amplitude distributions of light inside periodic photonic structures are visualized with subwavelength resolution. In addition, using a phase-sensitive photon scanning tunneling microscope, we simultaneously map the phase evolution of light. Two different structures, which consist of a ridge waveguide containing periodic arrays of nanometer scale features, are investigated. We determine the wavelength dependence of the exponential decay rate inside the periodic arrays. Furthermore, various interference patterns are observed, which we interpret as interference between light reflected by the substrate and light inside the waveguide. The phase information obtained reveals scattering phenomena around the periodic array, which gives rise to phase jumps and phase singularities. Locally around the air rods, we observe an unexpected change in effective refractive index, a possible indication for anomalous dispersion resulting from the periodicity of the array.

We present a new method of realizing single nanocavities in individual colloidal particles on the surface of silicon dioxide artificial opals using a focused ion beam milling technique. We show that both the radius and the position of the nanocavity can be controlled with nanometre precision, to radii as small as 40 nm. The relation between the defect size and the milling time has been established. We confirmed that milling not only occurs on the surface of the spheres, but into and through them as well. We also show that an array of nanocavities can be fashioned. Structurally modified colloids have interesting potential applications in nanolithography, as well as in chemical sensing and solar cells, and as photonic crystal cavities.

Optical field distributions around individually fabricated subwavelength scatterers mapped with a photon scanning tunneling microscope are presented. The photonic structures are produced from ridge waveguides using focused-ion-beam milling. This flexible technique allows us to make single holes and slits of sizes down to 30 nm. A quantitative analysis of the observed optical pattern due to interference between incoming and reflected light yields insight about subwavelength scatterers in waveguides. We conclude that light scattering into high-loss modes of the waveguide occurs.

To study the damping crisis encountered in offshore structures composed of circular members, the damping forces acting on a harmonically oscillating circular cylinder were determined. An experimental setup, in which representative values of the shear-wave number together with a sufficient amplitude-to-diameter ratio can be met is very difficult to realize. This might explain the lack of experimental data so far.