Reversal of the dipole vortex in a negative index of refraction material

When a small particle is illuminated by a circularly polarized laser beam, the induced electric dipole moment rotates in a plane. The flow lines of the emitted electromagnetic energy are the field lines of the Poynting vector. When the particle is embedded in a dielectric, these field lines have a vortex structure, and the rotation in the vortex has the same orientation as the rotation direction of the dipole. We show that when the embedding medium is a negative index of refraction material, the direction of rotation in the vortex is reversed.     

Parametric interaction of surface waves guided by a plasma layer

We study the linear stage of the parametric instability of high-frequency surface waves guided by a homogeneous plasma layer on a metallic substrate when a TM-polarized plane electromagnetic wave is incident on the layer. The instability growth rate and the threshold value of the pumping wave amplitude are determined. It is shown that the instability can be thresholdless in a certain range of permittivities and thicknesses of the layer. Radiophysical Research Institute, Nizhny Novgorod, Russia. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 40, No. 7, pp. 870–876, July, 1997.     

Self-localization of whispering-gallery modes in a spherical microcavity filled with a cold electron plasma

We have studied the mechanisms and conditions for self-localization of laser radiation in a cold collisionless electron plasma for a spherical microcavity in the quasistatic approximation, taking into account the appearance of striction nonlinearity and also relativistic effects connected with forced oscillatory motion of the electrons. We have shown that when whispering-gallery modes interact nonlinearly with the electron plasma, a spherical plasmon is excited which is localized within the finite volume of the microsphere. We have established that realization of self-localized spherical structures, in the form of an electromagnetic field and spherical plasmons within a microcavity filled with a cold electron plasma, is primarily due to appearance of relativistic nonlinearity of the medium. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 59–64, January–February, 2006.     

Possibilities of the method of phase-polarization selection of laser frequencies in strong fields

The spectra of Faraday rotation of the plane of polarization of laser radiation in strong radiation fields and a magnetic field were investigated for alkali atoms. The spectra were obtained using the known method of computer simulation of polarization effects in real multilevel atoms. The possibility of using these effects in the phase-polarization method of selection of laser frequencies was considered. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 67, No. 1, pp. 61–64, January–February, 2000.     

Optical activity of a cadmium diphosphide crystal

We have experimentally studied the characteristic features of a laser beam, polarized at angles of ± 45° to the horizontal (vertical), passing through plates of varying thickness cut from a CdP₂ crystal and placed between crossed polarizers, as a function of their angle of rotation relative to the vertical axis. We show that a periodic variation in the intensity is connected with the variation in polarization of the laser beam. We have established that the laser beam remains linearly polarized not only when it passes through the sample along the optic axis, but also when it travels at up to a 17.5° angle to the optic axis. In this case, the specific rotation of the plane of polarization along the optic axis is 68.2 degrees/mm for a thicker plate and 83.3 degrees/mm for a thin plate. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 5, pp. 690–693, September–October, 2006.     

Relativistic ponderomotive forces

The interaction of a relativistic classical electron with an inhomogeneous electromagnetic field is investigated. In second-order perturbation theory the motion is separated into fast and slow motions, and the relativistic Newtonian equation is averaged over the fast oscillations. The rate of change obtained for the slow component of the electron momentum is interpreted as a relativistic ponderomotive force. The result is generalized to the relativistic case of the wellknown expression for the Gaponov-Miller force acting on an electron at rest. The expressions obtained for the relativistic ponderomotive forces are very complicated in the general case. They simplify in the limit of a stationary field (pulses of long duration) and a small gradient. The most typical and simplest special case of an inhomogeneous field—a stationary plane-focused beam—is investigated. The main difference between relativistic ponderomotive forces and their nonrelativistic limit is they have multiple components. In addition to the usual force directed along the gradient of the field, the relativistic case is also characterized by force components that do not have the form of the gradient of a potential and are parallel to the wave vector and the direction of the field polarization. It is shown that when a relativistic electron travels in a direction close to the direction of the wave vector of a focused laser beam, these components can greatly exceed the gradient force. A force directed along the field polarization vector arises even when the gradient of the field in this direction is zero. Zh. éksp. Teor. Fiz. 116, 1198–1209 (October 1999)     

Twisted lines and small-scale structures in generation spectra of Yb-doped media excited by focused radiation of LiF:F 2 + color center laser

Spectral lines of Yb lasing in 1.03–1.05 μm region structured by 50–200 μm spots were found at focusing a pulsed LiF:F₂⁺ color center laser of 0.5–5.0 GW/cm² intensity on highly doped Yb:YAG or Yb:glass plates in a resonator. Small spots at the spectrograph located ≈ 1 m apart from the resonator indicated a “sub-diffraction” directivity of Yb generation, 1–2 orders better than the diffraction limit 10⁻³–10⁻² rad determined by the pumped volume dimensions. Observed features of Yb emission are explained assuming off-axis oscillations in Yb laser on phase-synchronized photons due to a strong spatial-angular selection of radiation in the resonator. Propagation of near diffraction free beams at angles to the axis built at the spectrograph slit for every 10–15 ns pulse of Yb generation a magnified “image” of a structure of generating channels in the active medium. This image projection brought a corresponding structure of spots in Yb spectra. It was found that channels may be formed due to a high-frequency spatial modulation (micrometers scale) of the refractive index profile in samples caused by the oscillating amplitude of thermoelastic stresses in the pumped medium. Obtained data demonstrate a possibility to study (with high spatial and temporal resolution) non-equilibrium stales of materials in small volumes using laser radiation emerging from these objects. This study results evidence for the novel concept of the spatial distribution of electromagnetic field of a photon: not in the form of a “travelling” wave but in the form of a wave with maxima and nodes located at fixed positions along the photon propagation direction.     

Surface currents on a perfect conductor, induced by a magnetic dipole

An oscillating magnetic dipole located near a perfect conductor induces a current density on the surface of the metal. We have derived an expression for this current density, and studied its field line patterns for various orientations of the dipole moment. When the dipole moment is perpendicular to the surface, the field lines are circles which run clockwise and counterclockwise. For a linear dipole oriented parallel to the surface, the field line pattern is much more complex, and it contains singular points. When the dipole moment rotates in a plane parallel to the surface, the field lines are spirals. A field line spirals inward from infinity to some given point, after which it spirals outward back to infinity. We have also considered the Poynting vector of the electromagnetic field near the surface, and we found that its field lines can have singular points or exhibit a vortex.     

From Euclidean to Minkowski space with the Cauchy–Riemann equations

We present an elementary method to obtain Green’s functions in non-perturbative quantum field theory in Minkowski space from Green’s functions calculated in Euclidean space. Since in non-perturbative field theory the analytical structure of amplitudes often is unknown, especially in the presence of confined fields, dispersive representations suffer from systematic uncertainties. Therefore, we suggest to use the Cauchy–Riemann equations, which perform the analytical continuation without assuming global information on the function in the entire complex plane, but only in the region through which the equations are solved. We use as example the quark propagator in Landau gauge quantum chromodynamics, which is known from lattice and Dyson–Schwinger studies in Euclidean space. The drawback of the method is the instability of the Cauchy–Riemann equations against high-frequency noise,which makes it difficult to achieve good accuracy. We also point out a few curious details related to the Wick rotation.     

Method for solving the electron-wave interaction problem

We examine a solution to the equations of motion of an electron in a plane electromagnetic wave in the presence of a constant magnetic field. The problem reduces to the solution of a parametric system of equations by the Lagrange and Byurman-Lagrange methods. This approach allows us to write out the solution to the equations of motion both for the forward motion of the electron along magnetic field force lines and for its reflection by the plane wave — a multivalued solution.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 76–83, September, 1989.In conclusion, the authors wish to thank I. M. Ternov for valuable critical comments that assisted in the presented paper.     

Highly oriented La2/3Ca1/3MnO3 films grown on silicon-on-insulator substrates by pulsed laser deposition

High quality La_2/3Ca_1/3MnO₄(LCMO) thin films have been deposited on silicon-on-insulator (SOI) substrates only buffered by yt tria-stabilized zirconia (YSZ) by using the pulsed laser deposition (PLD) technique. The results obtained from X-ray diffraction (XRD), reflection high energy electron diffraction (RHEED), scanning electron microscopy (SEM) and magnetization investigations indicate that the LCMO films are highly oriented both in-plane and out-of-plane. The Curie temperature T _c is close to 260 K and the insulator–metal (I–M) transition appears around 220 K. The conducting mechanism at low temperatures is dominated by the electron–magnon scattering. A tensile stress from the film–substrate lattice mismatch results in magnetic ‘easy axes’ in the film plane and the magnetic anisotropy energy increases with cooling. A maximum magnetoresistance (MR) is observed near 190 K, with the external magnetic field either parallel or vertical to the LCMO film plane. Moreover, the large intrinsic high-field magnetoresistance (HFMR) and the very small extrinsic low-field magnetoresistance (LFMR) again reveal that the LCMO films on SOI substrates are highly oriented thin films of good crystallinity.     

Frequency dependence of the coefficient of microwave radiation reflection from magnetic fluid at liquid nitrogen temperatures

The coefficient of microwave radiation reflection from a plane layer of a magnetic fluid magnetized by a magnetic field of 11.5 kOe is measured in the temperature range 253–293 K. The concentration of the magnetic phase (magnetite) is 15 vol %. In this temperature range, the dynamic susceptibility of nanoparticles exhibits strong dispersion (ferromagnetic resonance). Experimental data are treated by invoking the theory of high-frequency magnetization of an ensemble of interacting isotropic superparamagnetic particles. It is shown that, when the temperature drops below the room value, the trends observed at elevated temperatures (a decrease in the fraction of the power reflected from the magnetic fluid and an increase in the frequency of a minimum in the frequency dependence of the power) are retained.     

Shaping dynamics and structure of large-scale surface plasma formations under single-pulse laser action on various materials

It is established that, in the case of laser action on materials in large illuminated spots in atmospheric-pressure air for a laser radiation power density q≤2 MW/cm² (λ=1.315 μm), an evaporative regime with plane scattering of the laser-produced erosion plasma is realized while, for q≈5–17 MW/cm², the plasma front is transferred to the air, leading to plasma screening of the target and shaping of a subsonic radiation wave in the air. As the duration of the laser pulses increases (τ∼160 μsec), in spite of the large illuminated spots (S∼150 cm²) the evaporative regime of the laser action with plane plasma scattering goes over into a regime with jet outlow and formation of a quasistationary shock wave. Deceased. Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 65, No. 2, pp. 261–268, March–April, 1998.     

On the Electromagnetic Origin of Inertia and Inertial Mass

We address the problem of inertial property of matter through analysis of the motion of an extended charged particle. Our approach is based on the continuity equation for momentum (Newton’s second law) taking due account of the vector potential and its convective derivative. We obtain a development in terms of retarded potentials allowing an intuitive physical interpretation of its main terms. The inertial property of matter is then discussed in terms of a kind of induction law related to the extended charged particle’s own vector potential. Moreover, it is obtained a force term that represents a drag force acting on the charged particle when in motion relatively to its own vector potential field lines. The time rate of variation of the particle’s vector potential leads to the acceleration inertia reaction force, equivalent to the Schott term responsible for the source of the radiation field. We also show that the velocity dependent term of the particle’s vector potential is connected with the relativistic increase of mass with velocity and generates a longitudinal stress force that is the source of electric field lines deformation. In the framework of classical electrodynamics, we have shown that the electron mass has possibly a complete electromagnetic origin and the obtained covariant equation solves the “4/3 mass paradox” for a spherical charge distribution.     

Calculation of the characteristics of radiative multiphoton absorption and emission lines when an atom interacts with pulsed laser radiation

We have used the quantum electrodynamic theory of moments and the S-matrix formalism of Gell-Mann and Low to carry out numerical modeling of the characteristics (shift, width) of radiative multiphoton absorption lines for an atom in the field of a multimodal laser pulse with gaussian and soliton-like shapes. We have studied the effect of multimode character on the characteristics of multiphoton resonances, using as an example the 6S-6F transition in the cesium atom at the wavelength 1059 nm. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 2, pp. 271–274, March–April, 2007.     

Test of a model coupling of electromagnetic and gravitational fields by using high-frequency gravitational waves

Models of the coupling of electromagnetic and gravitational fields have been studied extensively for many years. In this paper,we consider the coupling between the Maxwell field and the Weyl tensor of the gravitational field to study how the wavevector of the electromagnetic wave is affected by a plane gravitational wave. We find that the wavevector depends upon the frequency and direction of polarization of the electromagnetic waves, the parameter that couples the Maxwell field and the Weyl tensor, and the angle between the direction of propagation of the electromagnetic wave and the coordinate axis. The results show that this coupling model can be tested by the detection of high-frequency gravitational waves.     

Structure and optical properties of carbon films obtained by multipulse pulsed laser deposition

We have obtained carbon thin films on silicon and glass substrates with multipulse pulsed laser irradiation of graphite under vacuum (p ≈ 2.6 Pa) using a high-frequency series of nanosecond laser pulses (τ = 85 ns, λ = 1060 nm) with pulse repetition frequency f ≈ 10–20 kHz and laser power density q ≈ 15–40 MW/cm². We established the optimal laser power density and laser pulse repetition frequency for obtaining amorphous nanostructured diamond-like films.     

空间散斑场捕获大量吸光性颗粒及其红外显微观测

光镊技术被广泛应用于捕获和操纵微纳米尺寸颗粒,主要包括捕获水中透明性颗粒和空气中吸光性颗粒两种类型.本文用激光束照射毛玻璃散射片,透射光经透镜会聚后在透镜的像平面附近产生了主观散斑场.该散斑场为空间分布,包含大量的亮斑和暗斑.大量由亮斑包围的暗斑如同一个个空间能量陷阱,被用来捕获大量的吸光性墨粉颗粒,被捕获颗粒的尺寸约2—8μm,密度约1—2 g/cm3.采用红外显微镜拍摄到空间散斑场捕获颗粒的红外像,红外图像显示被捕获颗粒吸光后温度升高,证实了空间散斑场捕获吸光性颗粒的机理为光泳力原理.     

Self-oscillations of electronic and nuclear polarization during optical excitation of an Si/CaF2 nanostructure in a transverse magnetic field

We examine theoretically low-frequency and high-frequency self-oscillations of electronic and nuclear polarization in an Si/CaF₂ nanostructure in a transverse magnetic field. We show that the low-frequency self-oscillations are stable in zero field, and the analogous high-frequency oscillations are stable beyond the region of the maximum on the Hanle curve. The frequency of the low-frequency oscillations is 0.001–0.500 of the reciprocal nuclear longitudinal relaxation time; the frequency of the high-frequency oscillations is 10⁸–10⁹ Hz, and their amplitude reaches 50% of the initial electronic spin polarization. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 3, pp. 363–369, May–June, 2006.     

Motion of a particle in a static magnetic field and in the field of a electromagnetic plane wave

The solutions of the equations of motion of a charged particle in an external electromagnetic field consisting of a superposition of a constant uniform magnetic field and the field of a circularly polarized electromagnetic plane wave are presented as solutions of the Cauchy problem. The resonance case is studied. Zh. Tekh. Fiz. 67, 94–99 (February 1997)