Оптические и фотолюминесцентные свойства тонкой пленки оксида цинка на подложке из тантала лития

Presents the results of the study of the structural, optical and photo luminescent properties of the thin films ZnO on LiNbO3 substrate. The results of X-ray structural analysis of a zinc oxide film synthesized on a single-crystal LiTaO3 substrate and on a KU-1 quartz substrate are presented. Present the transmission spectra, reflection spectra and the spectral dependence of zinc oxide thin films on substrate LiTaO3 and the structure of ZnO-SiO2 in the ultraviolet and visible spectral ranges.

DEVELOPMENT OF A BROADBAND ELECTROMAGNETIC RADIATION ABSORBER BASED ON MULTIWALL CARBON NANOTUBES AND ITS APPLICATION IN BOLOMETRIC RECEIVERS

This work is devoted to the development of a technique for obtaining an array of multi-walled vertically aligned carbon nanotubes (VACNT) with a thickness of up to 120 μm on Si/Al2O3/Fe substrates and to the study of their absorbing properties in the THz spectral region, as well as to the assessment of their prospects as a broadband THz radiation absorber based on calculations of the spectral dependence of absorption coefficient for traditional and inverted-type bolometric devices. It is shown that the absorption of the VACNT array transferred onto the Revalpha polymer substrate reaches 70–80% in the wavelength range of 40–200 µm. Calculations show that traditional bolometers with an absorber based on VACNT have the best sensitivity at wavelengths less than 100 μm, and inverted bolometers also having a VACNT layer have the best sensitivity at wavelengths exceeding 50 μm, which makes them complementary to each other.

INVESTIGATION OF THE INFLUENCE OF CORRELATED COLOR TEMPERATURE OF LED illuminatorS AS A FACTOR OF SAFETY LIGHTING OF HIGHWAYS FOR DIFFICULT WEATHER CONDITIONS

A investigation of the dependence of relative horizontal illumination level and brightness of the most common types of road surface in Ukraine when using LED illuminators with different spectral distribution of radiation in the presence of aerial aerosols of different optical densities (strong, moderate, weak fog and haze) is performed. Mathematical models of LED illuminators with correlated color temperature Tcc = (2200÷8400) K in the visible range of the spectrum λ = (380÷780) nm have been created. Their use together with the selected model of the spectral dependence of the scattering index β (λ) (Ferdinandоv’s model) of the atmospheric environment with the presence of aqueous aerosols, which cause a limited meteorological range of visibility MOR = (0.1÷3) km, showed a slight (1%) advantage in creation of illumination from lamps of a warm spectrum of radiation (TCC = 2200 K) in comparison with cold (Tcc = 8400 K) for cases of strong fogs with MOR = 100 m. Calculations involving the analysis of mathematical modeling of the spectral distribution of the reflection coefficients for two types of road surface (new and worn asphalt) proved that when using warm spectrum illuminators the brightness of the most common in Ukraine old asphalt pavement in the conditions of MOR = 100 m by 5% exceeds the corresponding value of the cold spectrum emitters. This difference gradually decreases as visibility is improved due to the weaker spectral dependence of β (λ) and at MV = 3 km is 4.5%. The advantage of using warm spectrum illuminators will be significantly enhanced for the case of estimating the brightness of the coverage over long distances, for example, airfield runways, which will significantly improve flight safety.

Fiber Optic Attenuator

A study of a bending-type fiber-optic attenuator has been carried out. It is shown that the use of G.655 - optical fiber provides the largest dynamic range of the attenuator. The spectral dependence of the bending losses was measured in a wide range of wavelengths: from 1270 to 1610 nm.

INTERBAND MULTIPHOTON ABSORPTION OF LIGHT IN THE KANE MODEL

The spectral dependences of the coefficients of interband three-photon optical transitions for InSb and for some optical transitions are calculated and a numerical analysis of the coefficient of interband three-photon absorption of light is carried out, which taken into account the contribution to the three-photon absorption of optical transitions occurring during the simultaneous absorption of two photons in the Kane model. Interband three-photon optical transitions in crystals of the InSb and type are classified, and the spectral dependence of some optical transitions is analyzed. The coefficient of linear-circular dichroism of interband three-photon absorption in a crystal in the Kane model is calculated. KEY WORDS: interband three-photon optical transitions, spectral dependence, crystal.

Kramers–Kronig Relation for Attenuated Total Reflection from a Metal–Dielectric Interface Where Surface Plasmon Polaritons Are Excited

The applicability of the Kramers–Kronig relation for attenuated total reflection (ATR) from a metal–dielectric interface that can excite surface plasmon polaritons (SPP) is theoretically investigated. The plasmon-induced attenuation of reflected light can be taken as the resonant absorption of light through a virtual absorptive medium. The optical phase shift of light reflected from the SPP-generating interface is calculated using the KK relation, for which the spectral dependence of ATR is used at around the plasmonic resonance. The KK relation-calculated phase shift shows good agreement with that directly obtained from the reflection coefficient, calculated by a field transfer matrix formula at around the resonance. This indicates that physical causality also produces the spectral dependence of the phase of the leakage field radiated by surface plasmons that would interfere with the reflected part of light incident to the interface. This is analogous with optical dispersion in an absorptive medium where the phase of the secondary field induced by a medium polarization, which interferes with a polarization-stimulating incident field, has a spectral dependence that stems from physical causality.

Interband Multiphoton Absorption of Light in Narrow-Gap Crystals

The spectral dependences of the coefficients of interband three-photon optical transitions for InSb and for some optical transitions are calculated and a numerical analysis of the coefficient of interband three-photon absorption of light is carried out, which taken into account the contribution to the three-photon absorption of optical transitions occurring during the simultaneous absorption of two photons in the Kane model. Interband three-photon optical transitions in crystals of the InSb and type are classified, and the spectral dependence of some optical transitions is analyzed. The coefficient of linear-circular dichroism of interband three-photon absorption in a crystal in the Kane model is calculated.

Mie–Raman-Fluorescence lidar observations of aerosols during pollen season in the north of France

Multiwavelength Mie–Raman–fluorescence lidar of Lille University with the capability to measure three aerosol backscattering, two extinction coefficients and three linear depolarization ratios together with the fluorescence backscattering at 466 nm was used to characterize aerosols during the pollen season in the north of France for the period March – June 2020. The results of observations demonstrate that the presence of pollen grains in aerosol mixture leads to an increase of the depolarization ratio. Moreover, the depolarization ratio exhibits a strong spectral dependence increasing with wavelength, which is expected for the mixture containing fine background aerosols with low depolarization and strongly depolarizing pollen grains. High depolarization ratio correlates with the enhancement of the fluorescence backscattering, corroborating the presence of pollen grains. Obtained results demonstrate that simultaneous measurements of particle depolarization and fluorescence allows to separate dust, smoke particles and aerosol mixtures containing the pollen grains.