The dissertation is devoted to finding out of mechanisms and basic regularities of appearance, behavior and interaction of topological defects of optical characteristics of heterogeneously perturbed glass and crystalline media.
The topological defects of optical indicatrix orientation, which are caused by inhomogeneous residual mechanical stresses in samples of glasses Li2B4O7, СаВ4О7 and LiB3O, are investigated experimentally. The criteria for the occurrence of topological defects of optical indicatrix orientation are formulated, such defects are experimentally detected in glasses with inhomogeneous residual mechanical stresses and it is shown that annealing of the samples leads to the disappearance of these defects. Criteria based on the properties of topological defect of optical indicatrix orientation, on the basis of which it is possible to distinguish 2D and 3D distributions of optical anisotropy parameters, are formulated and experimentally confirmed. These criteria can be used in the tomography of the tensor field of mechanical stresses. The technique of determination of sign of strength of topological defect of optical indicatrix orientation is developed and tested. It is shown that helical dislocations of the crystalline structure in crystals belonging to trigonal and cubic symmetry groups lead to topological defects of optical indicatrix orientation with strength ½ and helical dislocations of the light wave front. The edge structural dislocations in cubic and trigonal crystals, leading to topological defects of optical indicatrix orientation with strength 1, causing axially asymmetric polarization singularities in light beams propagating along these axes. The results of the analysis of topological defects of optical indicatrix orientation and the optical vortices generated by them in crystals containing structural dislocations can be used to detect and identify different types of structural dislocations that occur in crystals.
It is shown that double charged optical vortices can be generated using the Kerr electro-optical effect and applied to single crystals and isotropic media conical electric field. It has been established that crystals, textures, and isotropic materials, suitable for the creation of double charge optical vortices, must belong to the symmetry groups 622, 6mm, 6/mmm, 6, 6/m, ∞/m, ∞, ∞2, ∞mm, ∞/mmm, ∞/∞/mmm, and ∞/2. The topological defects of optical indicatrix orientation behavior under the coexistence of electro-optical Pockels and Kerr nonlinearities in crystals of cubic, hexagonal, trigonal and tetragonal systems under the action of an electric field of a conical shape is investigated. Topological reactions of birth, addition, division, and annihilation of topological defects of optical indicatrix orientation at different values of electric field are found. It is revealed that when the divergent optical beam propagates along the third order symmetry axis and when a homogeneous electric field EX applied to LiNbO3 crystals, there is a topological reaction of division 1=½+½ of central topological defect of optical indicatrix orientation with a single strength by two defects whose strengths are equal to ½.
It is proposed a method for analyzing the efficiency of spin-to-orbit conversion of the angular momentum of light, which is based on the obtained ratios for the figure of merit for the electro-optical Pockels effect, bending and twisting crystals, allows to choose the most efficient materials for optical vortex generation. It is shown that among the known crystals, the highest figure of merit when using the twisting method have crystals LiNbO3, β-BaB2O4, α-BaB2O4, hexamethylenetetramine and KAl (SO4)2×12H2O, when using the bending method – ZnSe crystals, FK3 glass, and lexane, and when conically shaped field is applied – the Ві12ТіО20 crystal. A controlled gradient axicon based on crystal twisting is proposed.
The optical activity induced by inhomogeneous mechanical torsional stresses – torsion-gyration effect is experimentally detected. It is shown that optical activity arises under the action of twisting even in initially centrosymmetric crystals. The value of coefficient describing the torsion-gyration effect in the K8 optical glass is obtained experimentally and the torsion-gyration tensor component is determined (β152 = 3,96 ± 0,82)×10 – 17 m3/N). It is shown that the induced optical activity does not depend on the coordinates in the plane perpendicular to the axis of application of the torque and the direction of light transmission. It is obtained fifth-order axial tensors with intrinsic symmetry ε[V2]2V, which describe the effect of gradient piezogyration for all point symmetry groups of crystals and Curie symmetry boundary groups. It is found that the applications of mechanical torsion and bending and electric field with conical distribution, form topological defects of the orientation of the gyration tensor with half-integer strength.
