Sergey A. Yuvchenko

Analysis of the scatter growth in dispersive media with the use of dynamic light scattering

Analysis of the structure functions of intensity fluctuations of scattered laser light was applied to monitor the phase separation in probed disperse media. UV-cured mixtures of a liquid crystal and prepolymer were studied during the formation of the structure of dispersive polymer-liquid crystal (DPLC) composites. The experimentally observed features of light beating induced by dynamic light scattering in DPLC systems (the scaling properties of the structure functions, the narrowing of the beating spectrum for certain weight fractions of the liquid-crystalline component) were interpreted in terms of the discrete scattering model using the results of statistical modeling.

Nonlinear optical properties of open-ended amichair single-wall carbon nanotubes (SW-CNT)

Summary form only given: Optical properties of carboxylic acid functionalized open-ended armchair single-wall carbon nanotubes (SW-CNT) are studied by numerical simulations and in experiments. The polarizability, extinction, saturated absorbance and non-linear refraction are analyzed in various conditions for different types of SW-CNT and compared with experimental data.

Effect of the “inversion” of a scattering medium in layers of close-packed titanium dioxide nanoparticles

The features of the behavior of the diffuse transmission of layers of close-packed titanium dioxide nanoparticles in the visible and near infrared spectral ranges with an increase in the volume fraction f of the particles in a layer have been analyzed. It has been found that an increase in f for layers of small particles (about 25 nm) with a relatively low volume fraction (0.20–0.25) is accompanied by the expected decrease in diffuse transmission. At the same time, an increase in f for layers of large particles (about 100 nm) with a volume fraction of 0.45–0.50 results in a strong increase in transmission. The described phenomenon has been interpreted in terms of the concepts of inverse scattering systems, where the main scattering centers are air nanocavities in a TiO2 matrix rather than TiO2 particles in an air matrix.

Peculiarities of the statistics of spectrally selected fluorescence radiation in laser-pumped dye-doped random media

We consider the practical realization of a new optical probe method of the random media which is defined as the reference-free path length interferometry with the intensity moments analysis. A peculiarity in the statistics of the spectrally selected fluorescence radiation in laser-pumped dye-doped random medium is discussed. Previously established correlations between the second- and the third-order moments of the intensity fluctuations in the random interference patterns, the coherence function of the probe radiation, and the path difference probability density for the interfering partial waves in the medium are confirmed. The correlations were verified using the statistical analysis of the spectrally selected fluorescence radiation emitted by a laser-pumped dye-doped random medium. Water solution of Rhodamine 6G was applied as the doping fluorescent agent for the ensembles of the densely packed silica grains, which were pumped by the 532 nm radiation of a solid state laser. The spectrum of the mean path length for a random medium was reconstructed.

The improved z-scan technique: potentialities of the additional right-angle scattering channel and the input polarization control

The theoretical possibility of retrieving the additional information on the dielectric properties of the nanoparticles material by single scattering in suspensions was studied. We have demonstrated a method of recreating the dielectric function of the material in the fundamental absorption band using the closed aperture z-scanning with the simultaneous Rayleigh scattering intensity measurements and the polarization control of an input laser beam. A possibility to recreate the form factor of the non-spherical particles or anisotropic nonlinear sensitivity for the sphere-like particles was also observed.

Excitation of local surface modes in semiconductor nanoparticles in visible and near UV regions

The effect of excitation of local surface modes in semiconductor nanoparticles is studied experimentally and theoretically for various compounds: titanium dioxide, titanium nitride, tungsten disilicide, molybdenum disilicide. Enhancement of depolarizing properties for non-spherical titania nanoparticles (nanoplatelets and nanoribbons) associated with the excitation of local surface modes is considered. The possibility to retrieve the dielectric function spectrum from the depolarization factor measurements for low-dimensional nanoparticles is discussed.

Diffusing low-coherence interferometry of turbid media: an approach to transport parameters evaluation

The features of formation of interferometer output in the case of a broadband light source and random medium as a retro-reflector in the interferometer object arm are considered. It is shown for the large values of the pathlength difference the interferometer output decays exponentially with the decay rate dependent on the transport parameters of a probed random medium. This allows us to determine the transport mean free path of light propagation in the medium. This approach can e applied not only for the strongly scattering media, but also for scattering samples characterized by non-diffusive regime of light propagation.