arXiv subjects

Dmitry Kazantsev

Publications and source records attributed to Dmitry Kazantsev.

3 recordsLinked to original sources

arXiv2013

Artifact-free data recovery system for an ASNOM application

A digital signal acquisition system for an Apertureless SNOM (ASNOM) based on a digital signal processing (DSP) card is presented. An electromagnetic wave scattered by an AFM-like tip is initially detected by an optical homodyning in a Michelson interferometer, with a homodyne phase modulation caused by a periodic travel of the reference arm mirror. Utilizing a non-linear dependency of the tip scattering amplitude on a tip-sample separation distance, the non-fundamental components of a tip oscillation frequency are recovered in optical signal within each tip oscillation period. A detected value, corresponding mostly to the near-field modes of a tip-sample electromagnetic interaction, is then averaged over all reference phases. A modular structure of the data acquisition and signal recovery program allows modify easily the modes of operation and the recovery algorithms.

physics.ins-det↗

arXiv2013

ASNOM mapping of SiC epi-layer doping profile and of surface phonon polariton waveguiding

The apertureless SNOM mapping of the slightly-doped 4H-SiC epitaxial layer grown on a heavily-doped 4H-SiC substrate was performed with a cleaved edge geometry. ASNOM images taken at the light frequencies of a $C^{13}O_{2}^{16}$ laser show a clear contrast between the substrate and the epitaxial layer. The contrast vanishes at the laser frequency of $884cm^{-1}$, and gets clearer at higher frequencies $(923cm^{-1})$. This can be explained by changes in the local polarizability of SiC caused by the carrier concentration, which are more pronounced at higher frequencies. Since the light frequency is tuned up further ($935cm^{-1}$), a transversal mode structure appears in the ASNOM map, indicating a waveguide-like confinement of a surface phonon polariton wave inside the strip of an epi-layer outcrop.

physics.optics↗

arXiv2007

Nonlocal effects on the resonant dielectric surface observed by near-field optical probing in mid-infrared range

The local electromagnetic field distribution over the dielectric (SiC) surface illuminated by mid-IR light of frequency close to the lattice resonance was directly mapped with an apertureless scattering near-field optical microscope. Half of the sample surface was covered with a metal layer, in which some small $(0.2-10 μm)$ holes were formed. It was found, that due to the eliminating of collective surface polarization effects, the amplitude of the electromagnetic field becomes several times higher over such holes than over infinitely open surface of the same dielectric.

physics.optics↗