Subwavelength grating Fourier‐transform interferometer array in silicon‐on‐insulator

A planar waveguide Fourier‐transform spectrometer with densely arrayed Mach‐Zehnder interferometers is demonstrated. Subwavelength gratings are used to produce an optical path difference without waveguide bends. The fabricated device comprises of an array of 32 Mach‐Zehnder interferometers, which produce a spatial interferogram without any moving parts, yielding a spectral resolution of 50 pm and a free‐spectral range of 0.78 nm. As a result of similar propagation losses in subwavelength grating waveguides and conventional strip waveguides, loss imbalance is minimized and high interferometic extinction ratio of −25 to −30 dB is obtained. Furthermore, phase and amplitude errors arising from normal fabrication variation are compensated by the spectral retrieval process using calibration measurements.     

Generation of electromagnetic waves in a spheroidal conductor by moving charges

The surface polarization fields generated by a charge moving near a spheroidal conductor are considered. The relations for surface plasmon dispersion are obtained. The polarization fields and energy losses of a moving charge are calculated.     

Radiation Losses of the Relativistic Charge Moving Near a Dielectric Radiator

Russian Physics Journal - The radiation losses of a relativistic charge moving in vacuum near a dielectric radiator in which Vavilov – Cherenkov radiation is generated are estimated. For a...     

Radiation of extended electromagnetic sources moving near the surface of a chiral medium

Current-carrying and charged filaments moving in vacuum along the plane surface of a semiinfinite chiral medium are investigated. The electromagnetic fields and energy losses due to radiation are found in both cases. The dependence of the radiation losses on the chirality constant is given. State Electrotechnical University of St. Petersburg, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 41, No. 7, pp. 866–873, July, 1998.     

Ionization losses of fast charged particles in an anisotropic medium

The energy losses of fast charged particles in anisotropic media are investigated. The macroscopic Maxwell equations are used to find the electromagnetic field of particles moving according to a given law in an anisotropic medium. A solution in quadratures is obtained for the energy loss of a charge moving at an angle to the optical axis of a weakly anisotropic uniaxial crystal; the result is in the form of a correction to the ionization losses in an isotropic medium. In the case of a medium consisting of anisotropic oscillators, an analytic formula is obtained for the correction: It is inversely proportional to the square of the velocity at particle velocities much less than the velocity of light and tends to zero for ultrarelativistic particles.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 1, pp. 14–19, January, 1978.Finally, it remains to thank O. B. Evdokimov for formulating the problem and for useful discussions.     

Squeezing with χ(3) materials

We assess in this paper the advantages and drawbacks of different nonlinear ⁽³⁾ materials for the purpose of generating squeezed light. The respective roles of nonlinearity, losses, response time and excess noise are discussed. Two simple models of nonlinear media are considered more precisely: parametric media with linear losses and an empty cavity with moving mirrors.     

Energy Characteristics of Wave Fields Radiated from Elementary Oscillators in a Nondispersive Medium Moving with Subluminal Velocity

We study the energy characteristics of fields radiated from electric, magnetic, and toroidal dipoles in a nondispersive medium moving with velocity lower than the speed of light in this medium. The angular dependences of Abraham's energy-flux density of electromagnetic field are analyzed. In particular, it is shown that if the medium velocity is high enough, then the radial component of the vector of energy-flux density is negative in a certain angular range. Expressions for the electromagnetic energy flux through a sphere of large radius are obtained. It is shown that if the velocity of a moving medium is high enough, then the energy flux is negative and its absolute value can exceed the energy losses of sources.     

Determination of the losses induced by irreversible barkhausen jumps of the 180° domain wall moving with a sinusoidal motion in the single domain wall model

The paper presents an analysis of the losses due to irreversible Barkhausen jump of the 180° Bloch wall in the single-domain wall model. The field-intensity and current-density vectors at unit input were determined for a single instantaneous jump. The losses were calculated for the case of the wall moving sinusoidally. The Parseval formula was used at determining the losses, which made it possible to perform calculations. A similar problem was considered by Allia and Vinai who adopted a simplified assumption of the domain of an infinitely long cylindrical shape.     

Energy Losses of a Charged Particle due to Excitation of Helicons in Plasma-Like Media

We study the energy lost by a particle moving along the helical line in a static magnetic field due to Vavilov–Cherenkov radiation of volume and surface helicons. It is found that the energy losses related to excitation of volume helicons are equivalent to the energy losses of a magnetic moment created due to the charge rotation. The magnetic moment moves at a constant velocity along the magnetic field. It is shown that collisionless damping of volume helicons in plasmas is based on the Cherenkov radiation of magnetic moment. Radiation of surface helicons by a particle does not correspond to the energy losses of a moving magnetic moment. This is related to the fact that not only magnetic (H) waves but also electric (E) waves contribute to the excitation of surface helicons, which leads to an increase in the energy losses of a particle.     

Next‐to‐next‐to‐leading order post‐Newtonian linear‐in‐spin binary Hamiltonians

The next‐to‐next‐to‐leading order post‐Newtonian spin‐orbit and spin(1)‐spin(2) Hamiltonians for binary compact objects in general relativity are derived. The Arnowitt‐Deser‐Misner canonical formalism and its generalization to spinning compact objects in general relativity are presented and a fully reduced matter‐only Hamiltonian is obtained. Several simplifications using integrations by parts are discussed. Approximate solutions to the constraints and evolution equations of motion are provided. Technical details of the integration procedures are given including an analysis of the short‐range behavior of the integrands around the sources. The Hamiltonian of a test‐spin moving in a stationary Kerr spacetime is obtained by rather simple approach and used to check parts of the mentioned results. Kinematical consistency checks by using the global (post‐Newtonian approximate) Poincaré algebra are applied. Along the way a self‐contained overview for the computation of the 3PN ADM point‐mass Hamiltonian is provided, too.     

Energy losses of dipoles traveling relative to a moving medium

We consider the radiation from nonoscillating dipoles traveling with constant velocity directed parallel or antiparallel to the velocity of a homogeneous transparent moving medium. It is assumed that the medium in its rest frame is isotropic and has no spatial dispersion. We obtain expressions for the radiative energy losses and estimate the polarization energy losses of electric and magnetic dipoles of different orientations. In particular, it is shown that the energy loss of a source is negative if it moves in the direction of the medium motion and the source velocity is less than the medium velocity. Estimates for the energy losses of dipoles in the cases of an electron beam and a flow of a weakly dispersive medium are given. __________ Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 49, No. 6, pp. 502–512, June 2006.     

Energy Losses in Collisions of Relativistic Structural Heavy Ions with Atoms

A nonperturbative theory of the energy losses in collisions of structural multiply charged heavy ions moving with relativistic velocities with atoms is worked out. Within the framework of this theory, by structural ions are meant ions containing partially filled electronic shells. It is such ions, having, as a rule, a considerable charge (for example, completely or partially stripped ions of uranium), that are used in many modern experiments on accelerators of heavy ions.     

Characterization of a sCMOS‐based high‐resolution imaging system

The detection system is a key part of any imaging station. Here the performance of the novel sCMOS‐based detection system installed at the ID17 biomedical beamline of the European Synchrotron Radiation Facility and dedicated to high‐resolution computed‐tomography imaging is analysed. The system consists of an X‐ray–visible‐light converter, a visible‐light optics and a PCO.Edge5.5 sCMOS detector. Measurements of the optical characteristics, the linearity of the system, the detection lag, the modulation transfer function, the normalized power spectrum, the detective quantum efficiency and the photon transfer curve are presented and discussed. The study was carried out at two different X‐ray energies (35 and 50 keV) using both 2× and 1× optical magnification systems. The final pixel size resulted in 3.1 and 6.2 µm, respectively. The measured characteristic parameters of the PCO.Edge5.5 are in good agreement with the manufacturer specifications. Fast imaging can be achieved using this detection system, but at the price of unavoidable losses in terms of image quality. The way in which the X‐ray beam inhomogeneity limited some of the performances of the system is also discussed.     

Stationary state of thermostated inelastic hard spheres

We consider a fluid composed of inelastic hard spheres moving in a thermostat modelled by a hard sphere gas. The losses of energy due to inelastic collisions are balanced by the energy transfer via elastic collisions from the thermostat particles. The resulting stationary state is analysed within the Boltzmann kinetic theory. A numerical iterative method permits to study the nature of deviations from the Gaussian state. Some analytic results are obtained for a one-dimensional system.     

Aerial ultrasonic micro Doppler sonar detection range in outdoor environments

Current research demonstrates that micro Doppler sonar has the capability to uniquely identify the presence of a moving human, making it an attractive component in surveillance systems for border security applications. Primary environmental factors that limit sonar performance are two-way spreading losses, ultrasonic absorption, and backscattered energy from the ground that appears at zero Doppler shift in the sonar signal processor. Spectral leakage from the backscatter component has a significant effect on sonar performance for slow moving targets. Sonar performance is shown to rapidly decay as the sensor is moved closer to the ground due to increasing surface backscatter levels.     

含原子运动非简并双光子JCM的光子统计性质

利用全量子理论,研究了与双模压缩真空场作用的含原子运动非简并双光子JCM中双模光场的光子统计性质着重讨论了不同初始态下原子的运动速度、模场结构和初始光强对光场的光子统计性质的影响,由此得到一些新的结论.     

动基座潜望式仪器瞄准线稳定时像倾斜的特性分析

潜望式仪器在动基座上实现瞄准线稳定时,会存在较明显的像倾斜。推导了动基座潜望式仪器瞄准线稳定时产生的像倾斜公式,分析了像倾斜的特性,得出了几点有意义的结论。提供了消除像倾斜的参数,为实现运动平台潜望式仪器图像稳定提供了一种途径。     

The Flow Patterns and Wall Stresses in a Louvered‐Wall Moving Granular Filter Bed of Quartz Sand

The flow patterns and wall stresses in a two‐dimensional louvered moving granular filter bed of quartz sand were investigated. The flow pattern histories of granular solids in the filter bed were recorded using a digital camcorder and a pressure gauge for simultaneously measuring the normal stresses as well as shear stresses of the granular solids. The static wall stress distributions produced by the granular solids were measured, and agreed with a theoretical prediction formed using the differential slice and Runge‐Kutta (order four) methods. The variations in the dynamic wall stresses with time in a moving granular filter bed were obtained and the effect of the louver angle upon the flow patterns and wall stresses was also investigated. Employing the results obtained by stress measurements and image processing, the wall pressure pulsation phenomena in a moving granular filter bed may be further understood. The results reported here provide fundamental information for the design of moving granular filter beds to act as high‐temperature flue gas cleanup filters.     

A Curved Noninteracting 2D Electron Gas with Anisotropic Mass

In da Costa's thin‐layer approach, a quantum particle moving in a 3D sample is confined to a curved thin interface. At the end, the interface effects are ignored and the quantum particle is localized on a curved surface. A geometric potential arises and, since it is due to this confinement procedure, it depends on the transverse to the surface mass component. The effects due to an anisotropic effective mass on a noninteracting two‐dimensional electron gas confined to a curved surface are reported. By tailoring the mass, many investigations carried out in the literature can be improved, which in turn can be useful to better designing electronic systems without modifying the geometry of the given system. Some examples are examined, such as a particle on a helicoidal surface, on a cylinder, on a catenoid and on a cone, with some possible applications briefly discussed.