Pattern Competition in the Photorefractive Semiconductors

We analytically study the photorefractive Gunn effect in n-GaAs subjected to two external laser beams which form a moving interference pattern (MIP) in the semiconductor. When the intensity of the spatially independent part of the MIP, denoted by $I_0$, is small, the system has a periodic domain train (PDT), consistent with the results of linear stability analysis. When $I_0$ is large, the space-charge field induced by the MIP will compete with the PDT and result in complex dynamics, including driven chaos via quasiperiodic route

Optically Driven Domain Instability and High-Frequency Current Oscillations in Photoexcited GaAs under Nonuniform Electron Heating

Fast domain instabilities induced by light-interference pattern in dc-biased semi-insulating GaAs are investigated. Current oscillations in GHz-frequency range are observed due to nonuniform electron heating and domains formation in light-induced grating. Characteristic features of the oscillations under various experimental conditions are presented. Numerical calculations based on the hot-electron hydrodynamic model are used to explain the observed nonlinear features under various external bias and periods of the grating

Optically Driven Domain Instability and High-Frequency Current Oscillations in Photoexcited GaAs under Nonuniform Electron Heating

Fast domain instabilities induced by light-interference pattern in dc-biased semi-insulating GaAs are investigated. Current oscillations in GHz-frequency range are observed due to nonuniform electron heating and domains formation in light-induced grating. Characteristic features of the oscillations under various experimental conditions are presented. Numerical calculations based on the hot-electron hydrodynamic model are used to explain the observed nonlinear features under various external bias and periods of the grating

Hot-Electron Effects in High-Resistivity InSb

We report that in the presence of random potential of the conduction band hot-electron transport can exhibit some novel features, some of which can be observed in dependencies of electric conductivity, mean electron energy and noise temperature on electric field strength

Analysis of locomotive wheel sets wearing

Wearing dynamics of traction rolling-stock wheel tyres of diesel locomotives was investigated. Based on research results it is possible to predict wheel-tyre safety margin, to improve maintenance and state periodicity of repair, as well as to use traction rolling-stock repair funds most efficiently

On Oscillating Carrier Dynamics in Highly Excited InP:Fe Crystals

The numerical analysis and experimental data on time-resolved four-wave mixing confirmed a novel origin of oscillations in subnanosecond carrier dynamics in highly excited InP:Fe crystals. The effect was attributed to simultaneous presence of electron and hole gratings, which drift in the space charge field and contribute constructively or destructively to refractive index modulation in time domain

High-Speed Quadratic Electrooptic Nonlinearity in dc-Biased InP

We present experimental data on degenerate four-wave mixing as well as simulation results of fast optical nonlinearities in highly-excited semi-insulating InP under applied dc-field. Hot-electron transport governed enhancement of optical nonlinearity is obtained by applying a dc-field of 10-14 kV/cm at full-modulation depth of a light-interference pattern. The hydrodynamic model, which incorporates both free-carrier and photorefractive nonlinearities is used to explain the experimentally observed features. We show that the enhancement of optical nonlinearity is due to the quadratic electrooptic effect

Electrical conductivity of single-wall carbon nanotube films in strong electric field

Citation: J. Appl. Phys. 113, 183719 (2013); doi: 10.1063/1.4804658(Received 6 March 2013; accepted 26 April 2013; published online 14 May 2013) Carrier transport features in single-wall carbon nanotube (SWCNT) films under strong electric fields (up to 105 V/cm) are presented. Application of electrical pulses of nanosecond duration allowed to minimize Joule heating and resolve intrinsic nonlinearities with the electric field. Investigations within a wide range of temperatures—4.2–300 K—indicated that carrier localization as well as tunneling through the insulating barriers between conducting regions takes place in SWCNT films. Crossover from semiconducting behavior to metallic behavior in strong electric field is described using the fluctuation induced tunneling model and assuming that the conducting regions demonstrate characteristic metallic conductivity. V C 2013 AIP Publishing LLC. [http://dx.doi.org/10.1063/1.4804658

High-Speed Quadratic Electrooptic Nonlinearity in dc-Biased InP

We present experimental data on degenerate four-wave mixing as well as simulation results of fast optical nonlinearities in highly-excited semiinsulating InP under applied dc-field. Hot-electron transport governed enhancement of optical nonlinearity is obtained by applying a dc-field of 10-14 kV/cm at full-modulation depth of a light-interference pattern. The hydrodynamic model, which incorporates both free-carrier and photorefractive nonlinearities is used to explain the experimentally observed features. We show that the enhancement of optical nonlinearity is due to the quadratic electrooptic effect