INVESTIGATION OF THERMAL RADIATION ANGULAR AND POLARIZATION CHARACTERISTICS OF ONE-DIMENSIONAL PHOTONIC STRUCTURES ON A FINITE SUBSTRATE

One-dimensional photonic structures (PS) are the layered metamaterials, which optical properties are due to interference effects within the structure. Due to the interaction of electromagnetic waves with the periodic structure, the thermal radiation (TR) of such PS has the features of coherent: it has a selective spectrum and a petal pattern. The relevance of TR PS research is due to the search for new materials to create sources of infrared (IR) radiation in the middle and far IR range (with a wavelength > 5 μm). The second important area of application of the radiating properties of the PS is the creation of non-radiating coatings to remove unwanted TR from the heated surfaces of the IR devices. Despite the fact that the irradiative properties of PS have been studied quite well, in the literature insufficient attention is paid to the influence of the finite substrate on the parameters of TR structures. The influence of a finite incoherent substrate on the angular and polarization characteristics of the thermal radiation of the system (photonic structure)/substrate has been investigated. Systems consisting of plane-parallel Ge or Si plates as PS and incoherent BaF2, BaF2/Al and Al substrates were used in experimental studies. It has been established, the contrast and amplitude of the directional diagram petals of the TR system depend on the ratio of the optical characteristics of the photonic structure and the substrate. The presence of a strongly reflective substrate eliminates the difference between the angular dependences of the s- and p-polarized components of the TR. In the case when the PS is placed on a transparent incoherent substrate with a lower refractive index, there is an increase in the p-polarized component of the TR and the suppression of the s-polarized. The thermal imaging picture of the TR angular distribution of the Si/Al system has been recorded and it was experimentally proved that the TR of photonic systems exhibits circular patterns. The results of the work can be used in the development of narrowband emitters in the middle and far infrared range, coatings to increase radiation energy exchange and coatings with minimal emissivity that are invisible in the thermal range.

Estimation of Rock Characteristics Based on Polarization Spectra: Surface Roughness, Composition, and Density

Surface polarization characteristics provide crucial structural information of the Earth's surface. As two key elements of the natural geographical environment, rocks and soils play an important role in the study of surface processes. Inherent surface characteristics, such as surface roughness, composition, and density are critical parameters for the remote monitoring of land surfaces as they affect the polarization characteristics of scattered light waves. In this study, we investigated the relationship between surface roughness, composition, and density, and the polarization spectra of limestone-dolomite series rock. Results reveal a power function relationship between the surface roughness and the degree of polarization peaks among different detection zenith and azimuth angles. The depth and position of the absorbing waveband are significantly correlated with the characteristic component contents. The rock density was determined via the polarized reflection spectra, with the Earth's surface density calculations associated with a 2.6% divergence from the current recognized data. Our results demonstrate the ability of polarized spectra to retrieve surface roughness, composition, and density, with potential for further development in future work.

Mathematical modeling of equivalent ellipse radii of Raman spectra for identification of gold nanoparticles

To ensure the biomedical, therapeutic and protective properties of textile materials using gold nanoparticles, there is a need to apply the convergence of nano-, bio-, info -, cognitive sciences and technology. It is proposed to evaluate the accuracy of identification of colloidal gold nanoparticles on organic fibers based on the multidimensional correlation components of the Raman spectra under control by the polarization characteristics. The aim of the work is to improve the accuracy of identification of gold nanoparticles in nanostructured biological objects during mathematical modeling based on the components of Raman spectrograms.The paper analyzes the Raman spectra of polyester fibers with and without gold nanoparticles in different ranges. A method for solving a system of multidimensional equations with differentiation in X and Y is proposed, according to which the coordinates of the intersection points of ellipses are determined under conditions of equality of equivalent radii and probability densities of two-dimensional distributions. The sensitivity to the concentration of gold nanoparticles of the developed method under various conditions is estimated. The research carried out in this work will improve the accuracy of identification of gold nanoparticles on various biological objects, as well as solve a wide range of problems related to increasing the reliability of control of metal nanoparticles

Polarization stability of the single-mode laser diodes radiation applied in radiation scattering study complexes

Key features of semiconductor lasers and its serially manufacturing technology modernization have greatly expanded of its using at applied studies at last 20 years. But there is set of factors restricting such lasers application in a number of optical-electronic measuring complexes. Particularly in particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) complexes commonly the gas and solid-state lasers is used due to more stability of spectral, energy and polarization characteristics of radiation then semiconductor lasers have. However gradual introduction of the serially manufacturing laser diodes into such systems picking up the pace that certainly characterizes the progress of reaching the required stability of its output laser radiation parameters. In laser measurement systems where medium investigation carried out by analyzing of scattering radiation in it the probe radiation polarization is often important. So the using in such systems the laser diodes as sources of radiation need to be followed by stability monitoring of its polarization characteristics which may be violated both by the outer factors and by natural degradation of inner laser diode structure. This work is devoted to the issues of monitoring the radiation polarization characteristics of the serially manufacturing single-mode laser diodes.

Multifunctional Partially Reflective Surface for Smart Blocks

In general, a partially reflective surface (PRS) is mainly used to increase the gain of an antenna; some metallic objects placed on the PRS degrades the antenna performance because the objects change the periodic structure of the PRS. Herein, we propose a multifunctional PRS for smart block application. When a passenger passes over a smart block, the fare can be simultaneously collected and presented through the LED display. This requires high gain antenna with LED structure. The high gain characteristic helps the antenna identify passengers only when they pass over the block. The multifunctional PRS has a structure in which an LED can be placed in the horizontal direction while increasing the antenna gain. We used the antenna’s polarization characteristics to prevent performance deterioration when LED lines are placed in the PRS. We built the proposed antenna and measured its performance: At 2.41 GHz, the efficiency was 81.4%, and the antenna gain was 18.3 dBi. Furthermore, the half-power beamwidth was 18°, confirming a directional radiation pattern.