Frolov D.S.,St Petersburg Electrotechnical University Leti |
Zubkov V.I.,St Petersburg Electrotechnical University Leti
Instruments and Experimental Techniques | Year: 2017
An apparatus for measuring nonequilibrium capacitance–voltage characteristics in semiconductor structures with electrolytic contacts is described. A pulse CV method was used in which a space-charge region in the deep-depletion mode was created via application of a bias-voltage pulse. Measuring the capacitance in a nonequilibrium mode makes it possible to avoid the formation of an inverse layer in an electrolyte–semiconductor system, whose presence leads to overestimation of the results of measuring the impurity concentration in narrow-band semiconductors. The possibility of applying this technique to measurements of the impurity concentration in weakly doped n-InAs is shown. © 2017, Pleiades Publishing, Inc.
Altmark A.M.,St Petersburg Electrotechnical University Leti |
Kanareykin A.D.,Euclid Techlabs LLC
Journal of Physics: Conference Series | Year: 2012
In this paper, we give a complete analytical solution for Cherenkov wakefields generated by an azimuthally asymmetric annular beam propagating in a coaxial two-channel dielectric structure. The transformer ratio of this type of structure is dramatically increased in comparison to a cylindrical wakefield accelerating structure. A particle-Green's function beam dynamics code (BBU-3000) to study beam breakup effects has been upgraded to incorporate annular drive beams and coaxial dielectric wakefield accelerating structures. Beam dynamics simulations of the annular drive beam with asymmetric charge distributions have been carried out to determine the sensitivity of this method to beam imperfections. © Published under licence by IOP Publishing Ltd.
Skobov V.G.,St Petersburg Electrotechnical University Leti |
Chernov A.S.,National Research Nuclear University MEPhI
Physics of the Solid State | Year: 2013
The influence of nonlinearity on propagation of radio waves into semimetals in the geometry where the constant magnetic field H is directed along the trigonal axis of the crystal has been investigated. Strong magnetic Landau damping occurs in the linear mode in this geometry. It is shown that the electron capture by the magnetic field of a radio frequency wave of large amplitude decreases this absorption. As a result, the depth of the skin layer in the semimetal becomes the function of the amplitude of the exciting radio frequency field and can increase many times. © 2013 Pleiades Publishing, Ltd.
Vendik O.G.,St Petersburg Electrotechnical University Leti |
Kozlov D.S.,St Petersburg Electrotechnical University Leti
IEEE Antennas and Wireless Propagation Letters | Year: 2012
A procedure of synthesis of an adaptive antenna array providing reduction of susceptibility to jamming or interference is presented. This approach is based on the sidelobe cancellation in the required direction. In this case, the form of the radiation pattern can be transformed by a modification of the system of sampling coefficients. An example of the forming of the required radiation pattern and corresponding current distribution is demonstrated. © 2011 IEEE.
Firsov D.D.,St Petersburg Electrotechnical University Leti |
Komkov O.S.,St Petersburg Electrotechnical University Leti
Technical Physics Letters | Year: 2013
A method for measuring photoreflectance (PR) by using a Fourier transform infrared (FTIR) spectrometer has been implemented. Features of application of the phase-correction method necessary for storing information on the sign of the spectrum were revealed. The method was applied for measuring the energy spectrum of charge carriers in InxGa1 - xAs/GaAs single quantum wells in the near-infrared range. A good agreement with the results obtained by means of a diffraction spectrometer for the same samples in the same wavelength range is observed. Application of the developed photomodulation FTIR spectroscopy method for measuring photoreflectance in InSb epitaxial layers in the wavelength range of 2-10 μm has been demonstrated. © 2013 Pleiades Publishing, Ltd.
Baruzdin S.A.,St Petersburg Electrotechnical University Leti
Technical Physics | Year: 2015
The excitation of a spin echo by two pulses with linear frequency modulation, upon which the pulse parameters ensure maximal compression of the response in time, is considered. The frequency of the excitation pulses was changed by a step law, approximating its linear rise. The transfer matrix of the state of the spin system for pulses with linear frequency modulation is found by solving the Bloch equations. The shape of the envelope of the spin echo in thin magnetic cobalt films, as well as the dependence of the echo amplitude on the parameters of the excitation pulses, is determined. The amplitudes of the excitation pulses, which ensure the excitation of the echo maximal amplitude for various values of the frequency deviation, are found. It is shown that the use of pulses with linear frequency modulation makes it possible to obtain the same echo amplitude as with the use of simple excitation pulses for a substantially smaller amplitude and power of excitation pulses. © 2015, Pleiades Publishing, Ltd.
Nikitin A.A.,St Petersburg Electrotechnical University Leti |
Kalinikos B.A.,St Petersburg Electrotechnical University Leti
Technical Physics | Year: 2015
A theory that describes the threshold regime of the formation of auto-oscillation spectrum is proposed for a tunable ring optoelectronic microwave oscillator (OEO). The main elements of the OEO are series-connected optical fiber, spin-wave narrow-band microwave film filter, and broadband semiconductor microwave amplifier. It is demonstrated that a relatively low level of the OEO phase noise is provided by both the optical fiber and spin-wave filter. © 2015, Pleiades Publishing, Ltd.
Khomyakov M.Y.,St Petersburg Electrotechnical University Leti
Pattern Recognition and Image Analysis | Year: 2012
A comparative evaluation of the most commonly used linear methods for edge detection in grayscale images are presented. Detectors based on the first and second derivatives of image brightness are considered. The method for automatic edge tracking in grayscale images is proposed. The model for assessing errors and artifacts caused by sampling during digitization of real input images is proposed. Investigation of edge detectors isotropy and errors caused by input images sampling is conducted. The advantage of the Isotropic operator for edge tracking is shown. The noise immunity of linear edge detection methods is assessed and the superiority of 3 × 3 gradient operators for noisy images is shown. Isotropic and Sobel operators are identified to be optimal on a basis of sampling errors, output noise level, and computational complexity. © 2012 Pleiades Publishing, Ltd.
Vendik I.B.,St Petersburg Electrotechnical University Leti |
Vendik O.G.,St Petersburg Electrotechnical University Leti
Technical Physics | Year: 2013
A metamaterial is a composite material that has attracted the attention of researchers since the late 1990s-early 2000s. This material contains an artificial periodic structure, which modifies its permittivity and permeability and, thereby, makes it possible to control the dispersion, refraction, and reflection of electromagnetic waves in the metamaterial. Analytical and experimental studies of the properties of metamaterials, as well as their applications, cover a wide frequency range from radio waves to the visible range. In recent years, considerable progress has been made toward the application of these materials in the microwave range (1-100 GHz). Works on development and application of metamaterials in the microwave range published over the last 8-10 years are reviewed. Artificial transmission lines as 1D metamaterials are discussed. Resonators, filters, and phase shifters based on the "metamaterial philosophy" are considered. Special attention is given to the application of metamaterials in the antenna technology. © 2013 Pleiades Publishing, Ltd.
Baruzdin S.A.,St Petersburg Electrotechnical University Leti
Optics and Spectroscopy (English translation of Optika i Spektroskopiya) | Year: 2016
The excitation of photon echo by noise pulses that are formed by modulation of the carrying frequency with Gauss noise is modeled. The modeling is based on optical Bloch equations the solution of which for noise pulse realizations is constructed by their stepwise approximation. In terms of the formalism of state transfer matrices, the two- and three-pulse excitation modes are analyzed. The complex envelopes of the primary and stimulated echo responses are determined. In the linear (low-level-signal) mode, the shape of the two-pulse echo corresponds to that of the time delayed and inverted noise pulse. The boundary of the linear mode, upon exceeding of which distortions of the shape of the noise pulse become noticeable, is determined. The shape of the stimulated (three-pulse) echo in the linear mode corresponds to that of the autocorrelation function of the noise pulse realization. Upon passage beyond the boundary of the linear mode, the shape of the three-pulse echo corresponds either to the cross-correlation function of distorted noise pulses (with different intensities) or to the autocorrelation function of distorted pulses (with the same intensities). The modeled photon echo excitation modes can be used in photon echo processors to process signals in the light range. © 2016, Pleiades Publishing, Ltd.