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Alexeyev C.N.,rnadsky Crimean Federal University | Lapin B.P.,rnadsky Crimean Federal University | Milione G.,City College of New York | Yavorsky M.A.,rnadsky Crimean Federal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2016

We have studied the influence of a twist defect in multihelicoidal Bragg fibers on the emerging of localized defect modes. We have shown that if such a fiber is excited with a Gaussian beam this leads to the appearance of a defect-localized topological state, whose topological charge coincides with the order of rotational symmetry of the fiber's refractive index. We have shown that this effect has a pronounced crossover behavior. We have also formulated a principle of creating the systems that can nestle defect-localized topologically charged modes. According to this principle, such systems have to possess topological activity, that is, the ability to change the topological charge of the incoming field, and operate in the Bragg regime. © 2016 American Physical Society.


Gusev A.N.,rnadsky Crimean Federal University | Shul gin V.F.,rnadsky Crimean Federal University | Efimov N.N.,RAS Kurnakov Institute of General and Inorganic Chemistry | Minin V.V.,RAS Kurnakov Institute of General and Inorganic Chemistry | And 2 more authors.
Russian Chemical Bulletin | Year: 2015

Dysprosium(iii) and neodymium(iii) complexes with aliphatic dicarboxylic acid bispicolyl-amidrazones were synthesized and studied. X-ray diffraction data showed that the compounds under study have a binuclear structure, in which the coordination polyhedra are bound by two aliphatic bridges. When excited with UV radiation, neodymium complexes exhibit weak ionic photoluminescence, while no luminescent activity was shown by dysprosium complexes. The temperature dependence of magnetic susceptibility of dysprosium complexes was studied. © 2015, Springer Science+Business Media New York.


Alexeyev C.N.,rnadsky Crimean Federal University | Lapin B.P.,rnadsky Crimean Federal University | Milione G.,City University of New York | Yavorsky M.A.,rnadsky Crimean Federal University
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2015

We have studied optical activity in optical fibers that possess multihelical distribution of the refractive index profile. We have demonstrated through an analytical treatment that the effect of optical activity is caused by asymmetric spin-dependent influence of the spin-orbit interaction on the coupling between the fundamental mode and the higher-order modes. We have provided a simple analytical expression for the coefficient of optical activity. © 2015 American Physical Society.


Dzedolik I.V.,rnadsky Crimean Federal University | Pereskokov V.,rnadsky Crimean Federal University
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2016

The TM-mode of surface plasmon polaritons (SPPs) can be excited at the interface of a metal layer and a dielectric medium. The E-mode of the SPPs is excited due to reflection of the TM-mode from the boundary of inhomogeneity in the metal layer. The interference of these modes leads to the formation of the SPP vortices in the points of minima of the mode field in some components of the Poynting vector of the SPP. The SPP interference vort expattern changes depending on the curvature of the boundary of inhomogeneity in the metal layer, and the vorti cesappear and disappear in the components of the Poynting vector. © 2016 Optical Society of America.


Lelyakov A.P.,rnadsky Crimean Federal University
Gravitation and Cosmology | Year: 2015

We consider the dynamics of a test null string in the gravitational field of a closed null string of constant (invariable in time) radius, whose direction of motion is at any time orthogonal to the plane in which the null string is located. An analysis of the solutions obtained makes it possible to assume that, in principle, some properties of a null string gas can be of interest from a cosmological viewpoint. For example, their ability of accelerated expansion and contraction, the opportunity of a grain structure, the ability to form stable polarized states and a domain structure. © 2015, Pleiades Publishing, Ltd.


Alexeyev C.N.,rnadsky Crimean Federal University | Lapin B.P.,rnadsky Crimean Federal University | Yavorsky M.A.,rnadsky Crimean Federal University
Optics Letters | Year: 2016

We have studied the effect of optical activity (OA) in optical fibers with multihelical distribution of refractive index profiles near the resonance wavelength, at which the conversion of an incident Gaussian beam into an optical vortex (and vice versa) takes place. We have shown that at such a wavelength the polarization vector of the input Gaussian beam rotates within the fiber at an average rate proportional to the difference in propagation constants of left- and right-circularly polarized optical vortices with the same topological charge. We also show that for certain fiber lengths the magnitude of OAcan greatly exceed its average level and reach anomalously high values. © 2016 Optical Society of America.


Alexeyev C.N.,rnadsky Crimean Federal University | Milodan A.V.,rnadsky Crimean Federal University | Alexeyeva M.C.,rnadsky Crimean Federal University | Yavorsky M.A.,rnadsky Crimean Federal University
Optics Letters | Year: 2016

In this Letter, we study the propagation of optical vortices (OVs) in a two-coil multimode fiber resonator. We suggest an analytical scheme of solving this problem based on its reduction to one of propagation of OVs in parallel evanescently coupled optical fibers. In the framework of the scalar approximation, we derive expressions for normal modes of the system and study evolution of an OV with an arbitrary topological charge excited at the input end of the resonator. We show that such a coil resonator is able to invert the topological charge of the incoming OV, provided the resonance condition is met. © 2016 Optical Society of America.


Pertel S.S.,rnadsky Crimean Federal University | Oselskaya V.Y.,rnadsky Crimean Federal University | Chirva V.Y.,rnadsky Crimean Federal University | Kakayan E.S.,rnadsky Crimean Federal University
Russian Chemical Bulletin | Year: 2015

A new 4-hydroxy glycosyl acceptor derivative of d-glucosamine containing a lactam-type N-protecting group was synthesized. The new glycosyl acceptor containing a hydroxy group at the C(4) atom was shown to be highly reactive in the glycosylation despite the presence of the amide (lactam) NH group. The high efficiency of the synthesized acceptor derivative is apparently attributed to the transformation of the (Z)-amide function that is present in amino sugar derivatives containing an acyclic acyl N-protecting group into the (E)-amide group in derivatives containing a lactam-type cyclic N-protecting group. This transformation leads to a radical change in the hydrogen bonding conditions and the character of molecular association. The observed effect can be employed to design new N-protecting groups providing high reactivity of glycosyl acceptor derivatives of D-glucosamine. © 2015 Springer Science+Business Media New York.

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