Vol 80, No 7 (2016)

Analysis of the orbital angular momentum of paraxial light beams shows that a key role in the formation of this quantity is played by phase relations between longitudinal and transverse radiation fields. When a light beam is circularly polarized or has a helical wave front, the azimuthal component of the Poynting vector and the density of orbital angular momentum prove to be non-zero. In the case of circularly polarized radiation, the azimuthal component of the Poynting vector and the density of the orbital angular momentum can change the sign at different points in the cross section of the light beam, while the total orbital momentum of the beam remains quantized.

The discrete diffraction of electromagnetic waves near the interface between two different media formed by waveguide arrays is studied. One of the arrays consists of waveguides made of a positive index material; the other, of waveguides made of a negative index material. The refraction of a beam resulting from diffraction at the interface obeys an analog of Snell’s law.

Conditions for the emergence of pseudoscalar vibrational excitations in the spectra of spontaneous and stimulated Raman scattering in molecular liquids and crystals are determined. The spectra of spontaneous and stimulated Raman scattering by pseudoscalar bosons are measured experimentally for several liquids and crystals.

A brief review of applications of the coherent states (CSes) in quantum optics is given. The CS representation of path integrals in the semi-classical approximation leads to the classical dynamics of CS parameters. Calculations of squeezing in the model of spontaneous parametric scattering are performed and the chaos in the collective dynamics of three-level atoms interacting with resonant photon modes is studied.

The precession of nuclear magnetic moments for a noble gas in an external magnetic field upon the laser pumping of nuclear magnetization is considered. A shift of the nuclear magnetic resonance for a mixture of noble gases with different gyromagnetic ratios of nuclei is observed.

Features of the generation of super radiance short pulses in a dielectric medium with quantum dots allowing for the nonlinear dissipative effects of the local field are considered. It is shown that the problem can be reduced to an equation of a nonlinear pendulum with an additional term for the harmonic loss/gain.

Methods of laser modification allow us to observe macroscopic quantum phenomena in nanostructured (cluster) materials. The laser synthesis of nanoparticles/nanoclusters with different topologies in semiconductor PbTe samples is performed via direct laser modification of thin films under the action of continuous laser radiation with a wavelength of 1.06 μm and a power density of ~10⁵ W/cm². Nanoparticles with bimodal distribution in lateral dimensions are obtained on the surfaces of the samples. The electrophysical properties of such structures can be controlled as desired by modifying their topology. Variations in electric properties depending on the particle location density are demonstrated. The results are interpreted based on the existence of quantum coherent processes with tunneling transitions and hopping conductivity. This approach is promising for the fabrication of elements and devices in optoelectronics and photonics based on new physical principles, and of different hybrid optoelectrical schemes.

The behavior of a two-dimensional light bullet propagating with a velocity greater than the speed of light in a medium consisting of semiconducting carbon nanotubes is investigated by means of numerical simulation. The electromagnetic field of the investigated system is described using Maxwell’s equations with allowance for the electric and magnetic properties of the carbon nanotubes and the medium in which they are embedded.

It is shown that in the presence of triplet levels of donor and acceptor molecules, the formula for function E(R) describing the dependence of efficiency E of Förster energy transfer on donor–acceptor distance R differs considerably from the one commonly used in experimental works.

The parameters of Franck–Condon and Herzberg–Teller interactions that form the fine-structure spectra of all-trans diphenyl polyenes in n-paraffin solutions at 4.2 K are analyzed. The effect the length of a polyene chain has on the emergence of benzene fragment bands is considered for four all-trans-diphenyl polyene compounds that differ by the number of π-conjugated bonds in the polyene chain.

Stochastic deformation and stress fields within a fractal multilayer nanosystem are investigated theoretically and by numerical modeling. It is shown that the averaged displacement functions of lattice nodes are complex. Their behavior changes from regular to stochastic when the control parameters are altered. A set of ultracold ²³Na atoms in an optical trap is chosen as the active nanoelement. It is demonstrated that certain physical properties (rate and quantization of the flow; hysteresis) of elementary excitations such as a vortex–antivortex pair are associated with the influence of a superfluid Bose–Einstein condensate (where a Higgs boson is the elementary excitation).