Second harmonic (SH) scanning optical microscopy in reflection is used to image the gold film surface covered with randomly placed scatterers. SH images obtained with a tightly focused tunable (750–830 nm) laser beam show small ($\sim 0.7\mu \mathrm{m}$) and very bright ($\sim {10}^3$ times the background) spots, whose locations depend on the wavelength and polarization of light. Comparing SH and fundamental harmonic (FH) images, we conclude that the localized SH enhancement occurs due to the overlap of FH and SH eigenmodes. The probability density function of the SH signal is found to follow the power-law dependence.

Elastic (in-plane) scattering of surface plasmon polaritons (SPP’s) is modeled by considering isotropic pointlike scatterers whose responses to the incident SPP field are phenomenologically related to their effective polarizabilities. Numerical simulations of single, double, and multiple scattering are presented for randomly situated scatterers showing the interplay between different orders of scattering and localization phenomena. Correlation between the scattering regimes and spatial Fourier spectra of the corresponding SPP intensity distributions is considered. Various optical microcomponents (e.g., straight and curved micromirrors) formed by sets of point scatterers are also simulated, and the stability and dispersion of their characteristics are investigated. The appropriate experimental results for SPP scattering by both random and specially configured sets of microscatterers are reported for two excitation wavelengths (594 and 633 nm) and different metal (silver and gold) films. The near-field optical images obtained are related to the calculated SPP intensity distributions demonstrating that the model developed can be successfully used in studies of SPP elastic scattering, e.g., to design the microcomponents for SPP’s.

We demonstrate experimentally generation of diffraction-free plasmonic beams with zeroth- and first-order Bessel intensity profiles using axicon-like structures fabricated on gold film surfaces and designed to operate at a wavelength of 700 nm. The central beam features a very low divergence ($\sim 8\pi \mathrm{mrad}$) for a narrow waist of the order of one wavelength and the ability to self reconstruct, which are the main signatures of diffraction-free beams.