Physics

Total Conversion of Terahertz Wave Polarization by Graphene Microribbon Array without Magnetic Field

Authors: Melnikova V. S., Polischuk O. V., Popov V. V.

The polarization conversion of terahertz radiation by the periodic array of graphene microribbons located at the surface of a high-refractiveindex dielectric substrate (prizm) is studied theoretically. Polarization conversion at the plasmon resonance frequencies takes place without applying external DC magnetic field. It is shown that giant (up to total) polarization conversion can be reached at the total internal reflection of THz wave from the periodic array of graphene nanoribbons.

Time-delayed Feedback Control of Coherence Resonance. Experimental Study

Authors: Semenov V. V., Vadivasova T. Е., Shell' E., Zakharova А. S.

In the paper a possibility to control the behavior of dynamic systems under conditions of coherent resonance using delayed feedback is proved experimentally. This problem is studied on the classical example of excitable system, which is the FitzHugh – Nagumo oscillator, as well as on the example of the Van der Pol oscillator with hard excitation, which also demonstrates the regime of coherent resonance. In both cases, when changing the delay time the feedback loop can both enhance and suppress the effect of coherent resonance.

Comparison of Methods for Phase Synchronization Diagnostics from Test Data Modeling Nonstationary Signals of Biological Nature

Authors: Borovkova E. I., Karavaev A. S., Ponomarenko V. I., Prohorov M. D.

Three methods of phase synchronization diagnostics from time series are compared by the analysis of test data. These data reproduce the statistics of experimental temporal realizations recorded from the system of human cardiovascular system autonomic control.

Model of the Miniature Modulator for Microwave Devices

Authors: Antonov I. N., Lavkin A. G., Mysenko M. B., Eryomin V. P., Rossoshanskiy A. V.

In the given paper the model of the miniature modulator for microwave devices is observed. The modulator consists of the master oscillator, which provides four series of the impulses, and of the inverter commutated with the surge generator providing a plate supply of the load. The pulsing plate supply of the load is stabilized by the current regulator on the unipolar transistor. The control and check unit realize the general control of the modulator. The optimal characteristic of the work of a magnetron is provided by the 16-digit microcontroller.

The Liquid Crystal Modulator on the Basis of the Waveguide Mode in the Twist Structure with the High Twist Angle

Authors: Simonenko G. V., Studentsov S. A., Ezhov V. A.

On the basis of the analysis of color characteristics of different LC display units the criterion for an assessment of an unchromaticity of black-and-white images is entered. For the adequate description of the optical properties of the LC modulator the necessary set of three characteristics is offered: contrast of the modulator, average on a range; the average on a range passage of the modulator for a status «is opened»; a modulator akhromatichnost is «open» for a status.

Optical Clearing of Human Eye Sclera by Aqueous 30%-Glucose Solution

Authors: Bashkatov A. N., Genina E. A., Kochubey V. I., Kamenskikh T. G., Tuchin V. V.

In this work, optical clearing of human eye sclera in vitro under action of aqueous 30% glucose solution was studied. It was shown that diffusion of glucose in tissue results in significant decrease of light scattering, which manifests itself in both decreasing reflectance and increasing transmittance of the samples. At that, absorption coefficient does not change. Measurements were performed with spectrophotometer CARY-2415 in the spectral range from 400 to 800 nm by a standard method.

Self-mixing Interferometry of Distance at Wavelength Modulation of Semiconductor Laser

Authors: Astakhov E. I., Usanov D. A., Skripal A. V., Dobdin S. Y.

Theoretical description for method of distance measurement at alteration emission wavelength of semiconductor laser, operated in self-mixing regime, has been presented. The result of computer modeling of self-mixing signal at harmonic wavelength modulation of laser diode has been represented. Spectral harmonic selection of low-frequency spectrum of self-mixing signal for distance measurement has been theoretically substantiated.

Digital Speckle Photography with Correlation Processing of Spatial Spectrum of Specklegram for Determination of Micro Displacement of Scattering Object

Authors: Maksimova L. A., Ryabukho P. V., Mysina N. Y., Ryabukho V. P.

The method of digital speckle photography for determining of speckle pattern displacement with sub-pixel accuracy using correlation processing of summary spatial spectrum of speckle patterns is considered in this article. It is assumed that displacement of speckle pattern is caused by deformation or displacement of an object with a scattering surface. The method of phase shift of interference pattern in diffraction halo is proposed for expanding the lower limit of measuring range of speckle pattern displacement to subpixel values.

Microwave Photonic Crystals. New Application Areas

Authors: Usanov D. A., Mardanov M. K., Skripal A. V., Ponomarev D. V.

The theoretical and experimental justifications of the possibility to use the microwave photonic crystals for the creation of broadband loads have been presented. The possibility to simultaneously determine the thickness and the conductivity of nanometer semiconductor layered structures by use of the microwave photonic crystals has been shown. The possibility of electrical control of the microwave photonic crystals amplitude-frequency characteristic has been experimentally demonstrated.

Research of the Contact Pads Topology Influence on the Parameters Reproducibility of the Current Oscillations in Mesa-Planar Structures Based on Semi-Insulatinggallium Arsenide

Authors: Kozhevnikov I. O., Mikhailov A. I., Bratashov D. N.

Experimental results of research the influence of the electric field distribution between the pads of mesa-planar resistor structures based on semi-insulating n-GaAs are represented. These influence by changing pads topology (plane-parallel, flat-pointed, counterpointed and concave-pointed) was studied for the current oscillations parameters (the threshold voltage, frequency and amplitude of current oscillations) reproducibility increasing.

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