Photorefractive Materials, Effects And Devices Prm'93
Oscillation in double phase conjugate mirror [1] with the local response medium (unshifted gratin... 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.
We report the experiments aimed at controlling the position of linear topological defect (disclin... more We report the experiments aimed at controlling the position of linear topological defect (disclination) in a so-called -cell filled with a nematic liquid crystal sandwiched between circularly rubbed polyimide (Kapton) layer and photoaligning PVCN material oriented unidirectionally. To satisfy surface-alignment conditions, the director within this cell experiences a twist. The topological defect appears in a plane where the twist angle of the director becomes indeterminate (90º). In an achiral liquid crystal, orientation of the disclination coincides with the alignment occurring on the unidirectionally oriented substrate. The idea of this work is to control the alignment direction on the substrate by a polarized ultraviolet light. Photo-induced director reorientation on the substrate changes the twist angle in the bulk and so varies the azimuthal angle of the disclination. We monitor reorientation of the disclination as a function of light-polarization angle and irradiation dose.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1981
_-The possibilities of the detection of extremely low atomic concentrations by laser atomic fluor... more _-The possibilities of the detection of extremely low atomic concentrations by laser atomic fluorescence were examined using Pb as an example. A detection limit of 250 atoms/cm3 or 30 atoms in the analytical volume was achieved in the experiments with saturated lead vapour in an evacuated quartz cell. A detection limit of 0.05 pglml was achieved in the experiments with aqueous solutions as reference using a graphite atomizer.
In this report we consider the elaboration of dye-doped POLIPHEM [1] (POlymer Liquid-crystal Poly... 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 st... 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...
2021 Fifteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials)
Wave propagation in metamaterials with different structure scales is analyzed with account of non... 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.
We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on th... more We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on the use of topological defects, namely disclination lines, created in chiral liquid crystals. The control of nanoparticle-loaded topological defects by low power light is demonstrated. Large-scale rotation, translation and deformation of quantum dots light-emitting chains is achieved by homogeneous LED illumination. Full reconfigurability and time stability make this approach attractive for future developments and applications.
We report a study devoted to the creation of a distributed feedback device on a basis of waveguid... more We report a study devoted to the creation of a distributed feedback device on a basis of waveguide with periodical composition polymer - liquid crystal. Due to the refractive indices difference between the components the Bragg diffraction grating is formed, which provides coupling of the forward and backward propagating waves. The influence of the gain and conditions of laser oscillation threshold are analyzed for gain-type reflection grating. The conclusion is done on the advantage of second-order Bragg diffraction exploitation. Numerical simulations demonstrated the stability of the waveguide mode.
A circular Laguerre-Gaussian mode transformation by an astigmatic lens is considered theoreticall... more A circular Laguerre-Gaussian mode transformation by an astigmatic lens is considered theoretically as an example of the higher-order optical vortex symmetry breakdown. Behind the lens, an m-charged optical vortex converts into jmj secondary first-order vortices whose evolution upon the beam propagation has been studied. In the beam cross section, they are positioned on a straight line crossing the beam axis. Orientation of this straight line is determined by the direction of the energy circulation within the incident beam. Depending on the parameters of the beam and the lens, in certain cross-sections all the secondary vortices can invert their signs; and in these sections (inversion planes) jmj edge dislocations (transverse vortices) appear. The morphology of secondary vortices is analyzed and the local orbital angular momentum of the nearest vicinity of an optical vortex core is shown to characterize the vortex anisotropy.
A structure of wavefront edge dislocations and associated “transversal” optical vortices in an in... 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
In a \mathcal Q-switched YAG:Nd3+ laser utilizing a three-mirror resonator a reproducible structu... 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
Spatial characteristics of the optical-vortex (OV) beams created during the Gaussian beam diffrac... 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 highorder 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.
Photorefractive Materials, Effects And Devices Prm'93
Oscillation in double phase conjugate mirror [1] with the local response medium (unshifted gratin... 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.
We report the experiments aimed at controlling the position of linear topological defect (disclin... more We report the experiments aimed at controlling the position of linear topological defect (disclination) in a so-called -cell filled with a nematic liquid crystal sandwiched between circularly rubbed polyimide (Kapton) layer and photoaligning PVCN material oriented unidirectionally. To satisfy surface-alignment conditions, the director within this cell experiences a twist. The topological defect appears in a plane where the twist angle of the director becomes indeterminate (90º). In an achiral liquid crystal, orientation of the disclination coincides with the alignment occurring on the unidirectionally oriented substrate. The idea of this work is to control the alignment direction on the substrate by a polarized ultraviolet light. Photo-induced director reorientation on the substrate changes the twist angle in the bulk and so varies the azimuthal angle of the disclination. We monitor reorientation of the disclination as a function of light-polarization angle and irradiation dose.
Spectrochimica Acta Part B: Atomic Spectroscopy, 1981
_-The possibilities of the detection of extremely low atomic concentrations by laser atomic fluor... more _-The possibilities of the detection of extremely low atomic concentrations by laser atomic fluorescence were examined using Pb as an example. A detection limit of 250 atoms/cm3 or 30 atoms in the analytical volume was achieved in the experiments with saturated lead vapour in an evacuated quartz cell. A detection limit of 0.05 pglml was achieved in the experiments with aqueous solutions as reference using a graphite atomizer.
In this report we consider the elaboration of dye-doped POLIPHEM [1] (POlymer Liquid-crystal Poly... 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 st... 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...
2021 Fifteenth International Congress on Artificial Materials for Novel Wave Phenomena (Metamaterials)
Wave propagation in metamaterials with different structure scales is analyzed with account of non... 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.
We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on th... more We report a strategy to assemble and manipulate nanoparticles arrays. The approach is based on the use of topological defects, namely disclination lines, created in chiral liquid crystals. The control of nanoparticle-loaded topological defects by low power light is demonstrated. Large-scale rotation, translation and deformation of quantum dots light-emitting chains is achieved by homogeneous LED illumination. Full reconfigurability and time stability make this approach attractive for future developments and applications.
We report a study devoted to the creation of a distributed feedback device on a basis of waveguid... more We report a study devoted to the creation of a distributed feedback device on a basis of waveguide with periodical composition polymer - liquid crystal. Due to the refractive indices difference between the components the Bragg diffraction grating is formed, which provides coupling of the forward and backward propagating waves. The influence of the gain and conditions of laser oscillation threshold are analyzed for gain-type reflection grating. The conclusion is done on the advantage of second-order Bragg diffraction exploitation. Numerical simulations demonstrated the stability of the waveguide mode.
A circular Laguerre-Gaussian mode transformation by an astigmatic lens is considered theoreticall... more A circular Laguerre-Gaussian mode transformation by an astigmatic lens is considered theoretically as an example of the higher-order optical vortex symmetry breakdown. Behind the lens, an m-charged optical vortex converts into jmj secondary first-order vortices whose evolution upon the beam propagation has been studied. In the beam cross section, they are positioned on a straight line crossing the beam axis. Orientation of this straight line is determined by the direction of the energy circulation within the incident beam. Depending on the parameters of the beam and the lens, in certain cross-sections all the secondary vortices can invert their signs; and in these sections (inversion planes) jmj edge dislocations (transverse vortices) appear. The morphology of secondary vortices is analyzed and the local orbital angular momentum of the nearest vicinity of an optical vortex core is shown to characterize the vortex anisotropy.
A structure of wavefront edge dislocations and associated “transversal” optical vortices in an in... 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
In a \mathcal Q-switched YAG:Nd3+ laser utilizing a three-mirror resonator a reproducible structu... 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
Spatial characteristics of the optical-vortex (OV) beams created during the Gaussian beam diffrac... 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 highorder 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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