Observation of local light propagation in ordered latex layers by scanning near-field optical microscope

Under the local excitation by a scanning near-field optical microscope, we have observed the transmission and luminescence excitation images of the hexagonally close-packed single layers of ordered, dye-doped polystyrene particles (LATEX) of 1.0 and 0.37 μm in diameter. The transmission images with the spatial resolution shorter than the optical wavelength dramatically changes, depending not only on the diameter of the particles but also on the aperture size of the probe tip end of the microscope. The luminescence excitation images for the single layers composed of particles, all or a part of which is dye-doped, give the information how the excitation light propagates through the layers. From these results we propose that the localized and extended modes of electromagnetic waves with large wave vectors propagating across and along the layers, respectively, are generated under the local excitation by the near-field effect