Vlokh Institute of Physical Optics

L'viv, Ukraine

Vlokh Institute of Physical Optics

L'viv, Ukraine
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Adamenko D.,Vlokh Institute of Physical Optics | Kushnirevych M.,Vlokh Institute of Physical Optics | Kokhan O.,Uzhgorod National University | Vlokh R.,Vlokh Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2015

We have studied experimentally the Faraday effect in Tl3AsSe4 crystals. The effective Faraday tensor coefficient and the Verdet constant are determined under normal conditions and λ=632.8 nm. They are equal to 0.06F11+0.94F22=(9.23±0.21)×10-13 m/A and VF=(82.2±1.8)rad/T×m, respectively. We have shown that the Tl3AsSe4 crystals are one of the most efficient magnetooptic materials among magnetically non-ordered ones. © 2015, Institute of Physical Optics. All rights reserved.


Kindrat I.I.,University of Zielona Gora | Padlyak B.V.,University of Zielona Gora | Padlyak B.V.,Vlokh Institute of Physical Optics | Drzewiecki A.,University of Zielona Gora
Journal of Luminescence | Year: 2015

Abstract The optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Sm-doped glasses with Li2B4O7, LiKB4O7, CaB4O7, and LiCaBO3 compositions were investigated and analysed. The Li2B4O7:Sm, LiKB4O7:Sm, CaB4O7:Sm, and LiCaBO3:Sm glasses of high optical quality have been obtained from the corresponding polycrystalline compounds in the air atmosphere, using a standard glass technology. On the basis of electron paramagnetic resonance (EPR) and optical spectra analysis it was shown that the samarium impurity is incorporated into the glass network as Sm3+ (4f5, 6H5/2) ions, exclusively. All observed 4f - 4f transitions of the Sm3+ centres in the optical absorption and luminescence spectra of the investigated glasses are identified. Most intense emission band of the Sm3+ ions peaked about 598 nm (4G5/2 → 6H7/2 transition) is characterised by a single exponential decay with typical lifetime values, which depend on the basic glass composition as well as concentration and local structure of the Sm3+ luminescence centres. The quantum efficiency has been evaluated for observed transitions of the Sm3+ centres using obtained experimental lifetimes and radiative lifetimes calculated by Judd-Ofelt theory. The calculated high quantum efficiencies and measured quantum yields of luminescence show that the investigated borate glasses are perspective luminescence materials. Energy transfer from the Ce3+ non-controlled impurity and intrinsic luminescence centres to the Sm3+ centres has been observed. Peculiarities of the Sm3+ local structure in the network of investigated glasses have been discussed based on the obtained spectroscopic results and structural data. © 2015 Elsevier B.V.


Mys O.,Vlokh Institute of Physical Optics | Kostyrko M.,Vlokh Institute of Physical Optics | Vasylkiv Y.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2015

Anisotropies of the acoustooptic figure of merit (AOFM) and the effective elastooptic coefficient under the conditions of collinear diffraction have been analyzed for LiNbO3 crystals. Narrow peak-like extremes have been revealed in the dependences of AOFM upon the orientation angle of the wave vector of the incident optical wave. We have also explained the reasons for the angular instability of the AOFM and the effective elastooptic coefficient. © 2015, Institute of Physical Optics. All rights reserved.


Mys O.,Vlokh Institute of Physical Optics | Kostyrko M.,Vlokh Institute of Physical Optics | Smyk M.,Vlokh Institute of Physical Optics | Krupych O.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Applied Optics | Year: 2014

We suggest a new approach for analyzing spatial anisotropy of an acousto-optic figure of merit (AOFM). The relations for the effective elasto-optic coefficients and the AOFM are derived for all possible types of acousto-optic (AO) interactions in optically isotropic media, including nonsolid-state and solid-state amorphous media and crystals belonging to the cubic system. Our approach allows for finding the optimal geometries of AO interactions characterized by the highest AOFM for a given material. The analysis is carried out on the examples of cubic KBr and KAl(SO4)2× 12H2O crystals, which represent different subgroups of the cubic symmetry class. © 2014 Optical Society of America.


Vasylkiv Y.,Vlokh Institute of Physical Optics | Kryvyy T.,Vlokh Institute of Physical Optics | Skab I.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2015

We study the behaviour of topological defects (TDs) of optical indicatrix orientation under the conditions when electrooptic Pockels and Kerr nonlinearities coexist in the crystals belonging to cubic, hexagonal, trigonal and tetragonal systems and a conically shaped electric field is applied along the principal crystallographic and/or optic axes. The topological reactions accompanying the processes of birth, addition, division and annihilation of the TDs of optical indicatrix orientation are observed under electric field variations. It is shown that the conservation law for the strength of TDs holds true under these topological reactions and the behaviours of the TDs can be exhaustively described by four different scenarios. © 2015 Institute of Physical Optics. All rights reserved.


Mys O.,Vlokh Institute of Physical Optics | Kostyrko M.,Vlokh Institute of Physical Optics | Krupych O.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2015

We present the developed method for analyzing the anisotropy of acoustooptic figure of merit (AOFM) for the case of anisotropic diffraction in optically uniaxial crystals, and we illustrate it on the example of crystalline paratellurite. We demonstrate that nine types of acoustooptic (AO) interactions can be implemented in general, six types for the isotropic interactions and three for the anisotropic ones. When the AO diffraction is collinear, the angular dependence of the AOFM is characterized by narrow peaks or dips. In the case of anisotropic diffraction, the maximum AOFMs for the paratellurite crystals are reached for the AO interactions of the type VIII with the acoustic wave QT1 propagated along the [110] direction and are polarized along [1 10]. The AOFM is equal to 929×10–15 s3/kg in this case. Nonetheless, the highest AOFM value for TeO2 crystals (1143.8×10–15 s3/kg) can be reached when linearly polarized optical eigenwaves interact isotropically with the transverse acoustic wave QT1 (see Mys O. et al, 2014. Ukr. J. Phys. Opt. 15: 132). This AO diffraction belongs to the type III. The results of our calculations agree well with the experimental data known from the literature. © 2015, Institute of Physical Optics. All rights reserved.


Vasylkiv Y.,Vlokh Institute of Physical Optics | Skab I.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Journal of Optics (United Kingdom) | Year: 2016

We develop an experimental method for the identification of the topological defects of optical indicatrix orientation, which appear in glass samples with residual mechanical stresses. The criteria needed to determine the sign of the strength of topological defects are formulated. The method is verified on the example of a non-annealed CaB4O7 glass sample that manifests spatially inhomogeneous residual stresses. We have found that at least seven topological defects of optical indicatrix orientation exist under the condition when a light beam propagates through a parallelepiped-shaped glass sample. The strengths of all the defects detected by us are equal to +1/2. © 2016 IOP Publishing Ltd.


Mys O.,Vlokh Institute of Physical Optics | Kostyrko M.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Applied Optics | Year: 2016

We have developed a method for the analysis of anisotropy of an acousto-optic figure of merit (AOFM), which is valid for the case of anisotropic diffraction in the trigonal crystals of the point symmetries 3m, 32, and 3m. The method is verified via the example of LiNbO3 crystals. The relations for the effective elasto-optic coefficients and the AOFM are obtained for the three types of acousto-optic (AO) interactions peculiar for the anisotropic AO diffraction: the interaction of a so-called type VII with a quasi-longitudinal acoustic wave and the interactions of types VIII and IX with two quasi-transverse acoustic waves. The AO diffraction geometries providing maximal AOFM values have been determined for each of the mentioned interaction types. We have found that the maximum AOFM proper for LiNbO3 is equal to 15.9 × 10-15 s3/kg. This value is achieved at the type IX of AO interactions in the interaction plane rotated by 60.0 deg around the principal X axis with respect to the principal X-Z plane. The type VIII of AO interactions is characterized by a comparable AOFM (15.1 × 10-15 s3/kg), which is realized in the Y CZ interaction plane. A close comparison of our results with the available experimental data demonstrates their fairly good agreement. © 2016 Optical Society of America.


Yu V.,Vlokh Institute of Physical Optics | Kryvyy T.,Vlokh Institute of Physical Optics | Skab I.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Ukrainian Journal of Physical Optics | Year: 2014

We have studied the behaviour of topological defects (TDs) of optical indicatrix orientation under the conditions when the electrooptic Pockels and Kerr nonlinearities coexist in cubic crystals and the axes of both conically shaped electric field and light beam are parallel to the crystallographic direction [111]. We have found that the electric voltage leads to a birth of three pairs of TDs. They are characterized by half-integer magnitudes of their strength and the opposite signs of that strength within the pairs. The above pairs of TDs annihilate with decreasing voltage. We have also shown that the total charge of relevant optical vortices is not conserved under topological reactions. © 2014, Institute of Physical Optics. All rights reserved.


Vasylkiv Y.,Vlokh Institute of Physical Optics | Skab I.,Vlokh Institute of Physical Optics | Vlokh R.,Vlokh Institute of Physical Optics
Journal of the Optical Society of America A: Optics and Image Science, and Vision | Year: 2014

In this work, we analyze the behavior of topological defects of optical indicatrix orientation induced by a conically shaped electric field in crystals in a crossover regime that appears at intermediate fields separating the regimes of prevailing Pockels and Kerr electro-optic nonlinearities. We have found that increases in the electric voltage applied to a crystal induce neither topological defects, with the strengths being not multiples of 1/2, or the optical vortices with fractional charges. Instead, there appear some additional topological defects of the optical indicatrix orientation, the behavior of which we have studied in detail. © 2014 Optical Society of America.

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