M. Vasnetsov
National Academy of Sciences of Ukraine, Institute of Physics, Faculty Member
Oscillation in double phase conjugate mirror [1] with the local response medium (unshifted gratings) is possible under following conditions [2]: 1) frequency detuning of oscillation waves with respect to the incident pump waves and 2)... more
Oscillation in double phase conjugate mirror [1] with the local response medium (unshifted gratings) is possible under following conditions [2]: 1) frequency detuning of oscillation waves with respect to the incident pump waves and 2) angular deviation of oscillation waves from strictly counterpropagation direction with respect to the pump waves.
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In this report we consider the elaboration of dye-doped POLIPHEM [1] (POlymer Liquid-crystal Polymer Holograms Electrically Manageable) holo-graphic material for the creation of distributed-feedback laser. The manufacturing of... more
In this report we consider the elaboration of dye-doped POLIPHEM [1] (POlymer Liquid-crystal Polymer Holograms Electrically Manageable) holo-graphic material for the creation of distributed-feedback laser. The manufacturing of electrically switchable holograms was performed by the process of photopolymerization and subsequent induced phase separation from an initially homogenous pre-polymer-liquid crystal mixture in the interference pattern of UV radiation. Stable gratings consist from the alternating planes of polymer network and regions of almost pure liquid-crystal regions filling the whole volume between the polymer walls without droplets formation. In POLIPHEM gratings, nematic liquid crystal molecules located between the polymer stripes are well aligned normal to the polymer-liquid crystal interface planes. Under the application of an external voltage, a strong variation of the refraction index modulation occurs due to the reorientation of the LC molecules [2]. Theoretical ana...
Soft material templating is a promising approach for assembling and manipulating nanoparticles structures. Due to the high sensitivity of soft matter systems to external stimuli, such composite materials exploit the soft surrounding... more
Soft material templating is a promising approach for assembling and manipulating nanoparticles structures. Due to the high sensitivity of soft matter systems to external stimuli, such composite materials exploit the soft surrounding medium to move or to reconfigure nano-structures or nano-objects as well as to tune their own properties. The use of topological defects in anisotropic fluids has been recently reported. Here, arrays of defect lines are created in planar-periodic nematic liquid crystal cells, wherein the nematic director undergoes static twist deformations separated by topological defects. Trapping and manipulation of the nanoparticles in disclinations are demonstrated and investigated by confocal fluorescence microscopy exploiting quantum dots. Nanoparticles gathering is observed during electrically controlled switching from orientational topological walls to disclinations. The external field is also used to perform displacement and deformation of the nanoparticles arra...
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Wave propagation in metamaterials with different structure scales is analyzed with account of nonlinear effects. We introduce topological nonlinearity and magnetooptical control over nonlinear strongly localized bullet-like structures... more
Wave propagation in metamaterials with different structure scales is analyzed with account of nonlinear effects. We introduce topological nonlinearity and magnetooptical control over nonlinear strongly localized bullet-like structures with phase singularities.
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A structure of wavefront edge dislocations and associated “transversal” optical vortices in an interference field of two two-dimensional Gaussian beams is analyzed. It was shown that the optical vortex rotation is directed toward the area... more
A structure of wavefront edge dislocations and associated “transversal” optical vortices in an interference field of two two-dimensional Gaussian beams is analyzed. It was shown that the optical vortex rotation is directed toward the area of higher phase velocity in the interference field (the origin of the phase velocity variation is due to the Gouy effect). The conditions for the
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In a \mathcal Q-switched YAG:Nd3+ laser utilizing a three-mirror resonator a reproducible structure of regular fluctuations was obtained with a period corresponding to the reciprocal of the width of the lasing spectrum. When the optical... more
In a \mathcal Q-switched YAG:Nd3+ laser utilizing a three-mirror resonator a reproducible structure of regular fluctuations was obtained with a period corresponding to the reciprocal of the width of the lasing spectrum. When the optical lengths of the partial resonators were not submultiples of the total length, random intensity fluctuations over the entire duration of the giant lasing pulse were observed. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
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Superpositions of coaxial Laguerre-Gaussian modes with common waists and the same Gaussian envelopes are known to form beams whose transverse structures experience the self-similar transformation during free beam propagation: the beam... more
Superpositions of coaxial Laguerre-Gaussian modes with common waists and the same Gaussian envelopes are known to form beams whose transverse structures experience the self-similar transformation during free beam propagation: the beam shape remains the same except for the divergence and rotation around the propagation axis. We show that under certain conditions this transformation can be represented as if every point of the beam cross section performs a centrifugal straight-line fly off.
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Spatial characteristics of the optical-vortex (OV) beams created during the Gaussian beam diffraction by a grating with groove bifurcation are analyzed theoretically and numerically. In contrast to previous works, condition of small-angle... more
Spatial characteristics of the optical-vortex (OV) beams created during the Gaussian beam diffraction by a grating with groove bifurcation are analyzed theoretically and numerically. In contrast to previous works, condition of small-angle diffraction is no longer required and the diffracted beam can be strongly deformed. This causes the intensity profile rotation and the high-order OV decomposition into a set of secondary single-charged OVs. These effects are studied quantitatively and confronted with similar properties of a Laguerre–Gaussian beam that undergoes astigmatic telescopic transformation. In contrast to the latter case, the secondary OVs do not lie on a single straight line within the beam cross section, and morphology parameters of the individual secondary OVs carried by the same beam are, in general, different. Conditions for maximum relative separation of the secondary OVs with respect to the beam transverse size are specified. The results can be used for practical generation of OV beams and OV arrays with prescribed properties.
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Two forms of the transverse energy circulation within plane-polarized paraxial light beams are specified: one inherent in wave-front singularities (optical vortices) and the other peculiar to astigmatism and asymmetry of beams with a... more
Two forms of the transverse energy circulation within plane-polarized paraxial light beams are specified: one inherent in wave-front singularities (optical vortices) and the other peculiar to astigmatism and asymmetry of beams with a smooth wave front. As quantitative measures of these energy flow components, the concepts of vortex and asymmetry parts of a beam's orbital angular momentum are introduced and their definitions are proposed on the basis of beam intensity moments. The properties and physical meaning of these concepts are analyzed, and their use for the study of transformations of optical vortices is demonstrated.
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The physical background of singular optics dealing with phase singularities in light waves is reported as a new chapter in modern optics. A review of the current status of nonlinear singular optics is presented.
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Currently, optical vortices (OVs), ie, areas of circu-lar motion of energy flow in an electromagnetic wave, are being actively studied in optics. Optical vortices can be divided into longitudinal OVs, where the axis of cir-cular motion... more
Currently, optical vortices (OVs), ie, areas of circu-lar motion of energy flow in an electromagnetic wave, are being actively studied in optics. Optical vortices can be divided into longitudinal OVs, where the axis of cir-cular motion coincides with the direction of wave prop-agation ...
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An analysis is made of the interaction of lasing in two coupled ring resonators with a shared holographic amplifier made of a photorefractive crystal. Derivation is given of relationships between intracavity losses when lasing occurs... more
An analysis is made of the interaction of lasing in two coupled ring resonators with a shared holographic amplifier made of a photorefractive crystal. Derivation is given of relationships between intracavity losses when lasing occurs simultaneously in two resonators or when it takes place in each of them separately. Competition between lasing waves, important in associative optical memory applications, is discussed. Bibtex entry for this abstract Preferred format for this abstract (see Preferences) Find Similar Abstracts: Use: Authors Title Abstract Text Return: Query Results Return items starting with number Query Form Database: Astronomy Physics arXiv e-prints
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This paper studies the optical angular momentum in periodic arrays. This work shows a gray-scale representation of the phase cross-section of a periodic array of optical vortices. The phase gradient gives rise to transverse linear... more
This paper studies the optical angular momentum in periodic arrays. This work shows a gray-scale representation of the phase cross-section of a periodic array of optical vortices. The phase gradient gives rise to transverse linear momentum, which in turn leads to a nonvanishing angular momentum density.
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Lasing interaction in two coupled ring resonators with a common holographic amplifier based on a photorefractive crystal is analyzed. Intracavity loss ratios are determined for which lasing occurs in both resonators simultaneously or in... more
Lasing interaction in two coupled ring resonators with a common holographic amplifier based on a photorefractive crystal is analyzed. Intracavity loss ratios are determined for which lasing occurs in both resonators simultaneously or in each one separately. The competition of lasing modes, which is relevant to problem in associative optical memory, is discussed.
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... The number of fringes radiatingfrom the center of the interference pattern equals the modulus of the topological charge, and the direction of the ... For vortices with multiple charge this operation will split an initially m-charged... more
... The number of fringes radiatingfrom the center of the interference pattern equals the modulus of the topological charge, and the direction of the ... For vortices with multiple charge this operation will split an initially m-charged vortexinto umu single-charge vortices @21#. ...
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We have predicted and observed an anisotropic photocurrent induced in the cubic crystal Bi(12)SiO(20) by a high-contrast interference pattern. The transverse current detected when the interference pattern is tilted is caused by deflection... more
We have predicted and observed an anisotropic photocurrent induced in the cubic crystal Bi(12)SiO(20) by a high-contrast interference pattern. The transverse current detected when the interference pattern is tilted is caused by deflection of the direct current generated by an external voltage applied to the crystal.