SNOM INVESTIGATION OF THE ELECTROMAGNETIC FIELD INTENSITY AND POLARIZATION DISTRIBUTION IN THE VICINITY OF NANOSTRUCTURES

The experimental and calculated results of the investigation of electromagnetic field distribution including its polarization characteristics in the vicinity of the nanostructures are presented. The experimental investigation was realized by aperture type scanning near field optical microscopes (SNOMs) which operated in collection mode. Normal resolution which allows us to image down to 0.3 nm height surface steps was demonstrated for the shear force probe to surface gap control system of the SNOM. Theoretical computation of the electromagnetic field distribution was realized by finite-difference time-domain (FDTD) method. The experimental three-dimensional maps of intensity and polarization distribution as a result of light diffraction at nanoaperture in the metal screen, dielectric and metallized nanocylinders were obtained. The qualitative difference between the orthogonal polarized component distributions near nanoaperture was experimentally shown. The electromagnetic field concentration in the proximity of the dielectric nanocylinders was observed. This observation gives a good fit with the results of FDTD computations. A spiral type electromagnetic field distribution pattern was experimentally observed in the proximity of metallized nanocylinders, which is unexpected from both experimental and theoretical points of view.