Institute of Physical Optics

L'viv, Ukraine

Institute of Physical Optics

L'viv, Ukraine
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Fadeyeva T.A.,Taurida National University | Fadeyeva T.A.,Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2013

In the framework of paraxial approximation we consider evolution of a monochromatic Gaussian beam diffracted by a corner formed by three verges of the phase wedges of different types and the π -phase plate. We have found that the edges of the phase wedge generate macroscopic chains of identical optical vortices that disappear at the far field zone. At the same time, the π -phase plate can reproduce a very complex wave field whose structure depends on the scale of observation. At large scales there appear two π -cuts resembling broken edge dislocations with perpendicular directions. At small (some microns) scales two short vortex chains consisting of alternating-sign optical vortices are nucleated near the corner of the wedge. The analysis shows that the sizes of the chains decrease quickly when approaching the wedge surface. This enables us to assume that the π -phase plate can create so-called optical quarks in the evanescent waves of the edge field.


Nastishin Yu.A.,Institute of Physical Optics | Nastyshyn S.Yu.,Ivan Franko National University of Lviv
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2013

An integral Jones matrix for oblique light propagation through a deformed crystal is derived using the differential Jones matrix approach. We show that generally at oblique light propagation a crystal monotonically deformed along its normal should show both linear and circular birefringence, even without twist deformation. The capability of the approach is illustrated by the calculation of the integral extended Jones matrices for oblique light propagation through several deformed liquid crystal nematic cells. In particular, we predict that at oblique light propagation in certain directions the nontwisted hybrid nematic cell (in which the tilt angle of the optic axis with respect to the crystal plate normal smoothly varies through the thickness) shows optical activity, a phenomenon of spatial light dispersion akin to so-called weak optical activity in nonchiral polar solid crystals. © 2013 American Physical Society.


Padlyak B.,Institute of Physical Optics | Padlyak B.,University of Zielona Gora | Drzewiecki A.,University of Zielona Gora
Journal of Non-Crystalline Solids | Year: 2013

A series of borate glasses of high optical quality with CaB 4O7:Tb, LiCaBO3:Tb, CaB4O 7:Dy, and LiCaBO3:Dy compositions containing 0.5 and 1.0 mol% Tb2O3 and Dy2O3 impurity compounds were obtained from corresponding polycrystalline compounds using standard glass technology. By electron paramagnetic resonance (EPR) and optical spectroscopy it was shown that the Tb and Dy impurities are incorporated as Tb3 + (4f8, 7F6) and Dy 3 + (4f9, 6H15/2) ions in the Ca and Li(Ca) sites of CaB4O7 and LiCaBO3 glasses network, respectively. The luminescence excitation and emission spectra as well as luminescence kinetics of the Tb3 + and Dy3 + centres in the CaB4O7 and LiCaBO3 glasses have been investigated and analysed in comparison with obtained earlier results for Tb3 + and Dy3 + centres in the Li2B 4O7 glasses. All observed f-f transitions of the Tb 3 + and Dy3 + centres in the luminescence excitation and emission spectra have been identified. Luminescence kinetics show single exponential decay for Tb3 + and Dy3 + centres in the CaB4O7 and LiCaBO3 glass network. The lifetime values for the main emitting levels of the Tb3 + and Dy3 + centres in all investigated glasses were determined at room temperature and their dependencies on the basic glass compositions and impurity concentrations are discussed. The obtained results show that the CaB4O7 and LiCaBO3 glasses are promising luminescent materials, operating in green and yellow-blue spectral regions, when activated with Tb3 + and Dy3 + ions, respectively. © 2013 Elsevier B.V.


Krupych O.,Institute of Physical Optics | Savaryn V.,Institute of Physical Optics | Vlokh R.,Institute of Physical Optics
Applied Optics | Year: 2014

A recently proposed technique representing a combination of digital imaging laser interferometry with a classical four-point bending method is applied to a canonical nonlinear optical crystal, LiNbO3, to precisely determine a full matrix of its piezo-optic coefficients (POCs). The contribution of a secondary piezo-optic effect to the POCs is investigated experimentally and analyzed theoretically. Based on the POCs thus obtained, a full matrix of strain-optic coefficients (SOCs) is calculated and the appropriate errors are estimated. A comparison of our experimental errors for the POCs and SOCs with the known reference data allows us to claim the present technique as the most precise. © 2014 Optical Society of America.


Skab I.,Institute of Physical Optics | Vasylkiv Y.,Institute of Physical Optics | Savaryn V.,Institute of Physical Optics | Vlokh R.,Institute of Physical Optics
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2011

We report the results of studies of the torsion effect on the optical birefringence in LiNbO3 crystals. We found that the twisting of those crystals causes a birefringence distribution revealing nontrivial peculiarities. In particular, they have a special point at the center of the cross section perpendicular to the torsion axis where the zero birefringence value occurs. It has also been ascertained that the surface of the spatial birefringence distribution has a conical shape, with the cone axis coinciding with the torsion axis. We revealed that an optical vortex, with a topological charge equal to unity, appears under the torsion of LiNbO3 crystals. It has been shown that, in contrast to the q plate, both the efficiency of spin-orbital coupling and the orbital momentum of the emergent light can be operated by the torque moment. © 2011 Optical Society of America.


Skab I.,Institute of Physical Optics | Vasylkiv Y.,Institute of Physical Optics | Smaga I.,Institute of Physical Optics | Vlokh R.,Institute of Physical Optics
Physical Review A - Atomic, Molecular, and Optical Physics | Year: 2011

In the present work we have demonstrated a possibility for operation by orbital angular momentum (OAM) of optical beams via the Pockels effect in solid-crystalline materials. Based on the analysis of an optical Fresnel ellipsoid perturbed by a conically shaped electric field, we have shown that the point groups of crystals convenient for the conversion of spin angular momentum (SAM) to OAM should contain a threefold symmetry axis or a sixfold inversion axis. The results of our experimental studies and theoretical simulations of the SAM-to-OAM conversion efficiency carried out for LiNbO3 crystals agree well with each other. © 2011 American Physical Society.


Skab I.,Institute of Physical Optics | Vlokh R.,Institute of Physical Optics
Applied Optics | Year: 2012

Acousto-optic diffraction of light in optically active cubic crystals is analyzed from the viewpoint of conservation of optical angular momentum. It is shown that the availability of angular momentum in the diffracted optical beam can be necessarily inferred from the requirements of angular momentum conservation law. As follows from our analysis, a circularly polarized diffracted wave should bear an orbital angular momentum. The efficiency of the spin-to-orbit momentum conversion is governed by the efficiency of acousto-optic diffraction.


Skab I.,Institute of Physical Optics | Vasylkiv Y.,Institute of Physical Optics | Vlokh R.,Institute of Physical Optics
Applied Optics | Year: 2012

We describe a method for generation of optical vortices that relies on bending of transparent parallelepiped-shaped samples fabricated from either glass or crystalline solid materials. It is shown that the induced singularity of optical indicatrix rotation leads in general to appearance of a mixed screw-edge dislocation of the phase front of outgoing optical beam. At the same time, some specified geometrical parameters of the sample can ensure generation of a purely screw dislocation of the phase front and, as a result, a singly charged canonical optical vortex. © 2012 Optical Society of America.


Nastishin Y.,Institute of Physical Optics | Dudok T.H.,Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2013

Currently optically pumped mirror less lasing is represented by three distinct branches, which concern lasing in different types of the gain media: optically random and photonic media, and micro cavities. This article is a first part of our review on optically pumped mirror less lasing, with the random lasing in scattering media being a main subject. The other mirror less lasing mechanisms will be addressed in the second part. Considering light localization as a key function of the feedback, we discuss possible mechanisms for the light localization in the scattering media. Special attention is paid to the Anderson light localization. The other mechanisms of the light localization in the scattering media concern high Q-resonances in local micro resonators, which exist due to structural in homogeneities in the scattered media. Applications of the random lasers are shortly reviewed.


Skab I.,Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2012

The torsion method for measuring piezooptic coefficients π14 and π25 in the trigonal crystals belonging to the point symmetry groups 3 and 3 is described. The XY-distributions of the optical indicatrix orientation and the optical birefringence induced by the torsion stresses are analysed and evaluated quantitatively. It is shown that the spatial birefringence distribution in the sample subjected to torsion around the Z axis represents a canonical cone. The combined piezooptic coefficient for lead germanate crystals is determined experimentally. It is shown that, for all of the point symmetry groups of trigonal system, the torsion torque applied around the directions of optic axes would lead to appearance of a purely screw dislocation of the phase front of the outgoing wave, while the corresponding optical vortex would possess a unit topological charge.

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