Gleb S. Zhdanov

Tunneling and spatial resolution in near-field optics

A simple model resembling those used in scanning tunneling microscopy is proposed for an optical probe tip. The tip is considered as a pointlike source (detector) displaced from the apex in the direction towards or from the sample. The exact position of this point depends on the shape of electric field lines within the gap and is a crucial factor determining the probe imaging properties. For various probes, both the aperture and apertureless ones, a general expression relating the lateral resolution with the corrugation amplitude, the gap width, and the tip (the aperture) radius is obtained.

Potential of near- and far-field techniques for the detection of nanoemitters on laser-illuminated surface

A simple technique for density determination of nm-sized light-emitting areas on a flat surface such as those produced by quantum dots is proposed. The method is based on the measurements of luminescence intensity fluctuations at the center of inhomogeneously broadened spectral band from a sample illuminated through a series of mask with apertures in the 0.1-1 micrometers range. The fluctuation amplitudes depend crucially on the number of emitters involved. As shown by simulation the latter may be established with better than 100 percent accuracy as well as the averaged surface density. With aperture diameter as small as approximately 0,2 (lambda) in-depth discrimination of QDs in the aperture near-field is possible.