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We demonstrate the generation of acoustic vortex beams with the aid of an acoustic spiral phase plate and an acoustic grating having a fork-like bifurcation of its slits. The acoustic vortex beam generated in this manner influences the particles floating on a water surface and rotates them. Our experiments show that the intensity of the acoustic vortex beam increases from zero in its center to a certain maximal value near the shell of the beam. The phase of the beam changes by the angle 2 π whenever the azimuthal angle is changed by the same value. We also study acousto-optic diffraction of the optical beam by the acoustic beam bearing a vortex and demonstrate that each of the appropriate diffraction maxima are split into two maxima. The latter correspond to diffraction by the elementary acoustic rays which are close to the opposite edges of the acoustic vortex beam. A dark region between the maxima appears due to destructive interference of the elementary optical rays originated from the diffraction by the opposite sides of the acoustic vortex beam, which are phase-shifted by π .

Generation of an array of optical vortices (OVs) with fractional charges under the condition of acousto-optic Bragg diffraction is revealed experimentally. The OVs emerge in a wide diffracted optical beam due to reflection from a thick acousto-optic grating that contains bifurcated fringes of acoustic waves (AWs). Changes in the AW frequency lead to deflection of the wide optical beam containing the OV array. The OVs preserve their spatial positions only in the narrow AW frequency range, while larger changes in the frequency impose their movement out from the beam aperture, with appearance of the other OVs in the other places of the beam cross section.

We have revealed that torsion stresses produce an optical activity effect in initially isotropic glass media. The optical activity caused by spatially inhomogeneous mechanical stresses has been experimentally studied for a standard glass BK7 subjected to torques, using a single-beam polarimetry and a polarizer-sample-analyzer scheme. The torsion-gyration coefficient for the BK7 glass has been determined as (3.96±0.82)×10 -17   m 3 /N.

We have revealed topological defects (TDs) of the angle of optical indicatrix (OI) orientation in a glass Li2B4O7 sample, which originate from the specific spatial distribution of optical birefringence caused by residual mechanical stresses. It has been found that the strength of TDs of the OI rotation angle is equal to ±1/2. Following from the experimental results, we have shown that the regions around the TDs of OI orientation are those of a 3D stressed state. We have formulated criteria for determining whether 2D or 3D distributions of the optical anisotropy parameters appear, based on the TDs of OI orientation. It has been shown that, in some particular cases, the regions with the TDs can testify the availability of a 2D stressed state. Besides, we have demonstrated experimentally that the TDs can appear for more than one projection in the case of 3D distributions of the OI parameters, which appear under bending of glass plates by a distributed load.

We show that double-charged optical vortices can be generated with the help of Kerr electro-optic effect in either single crystals or isotropic media, including gaseous and liquid ones. We analyze possibilities for the vortex generation via the Kerr effect for different point groups of symmetry and formulate the appropriate conditions. We prove that the crystals, textures, and the isotropic media most suitable for the generation of double-charged optical vortices should belong to the symmetry groups 622, 6mm, 6/mmm, 6, 6/m, ∞/m, ∞, ∞2, ∞mm, ∞/mmm, ∞/∞/mmm, and ∞/∞2.

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.

We show that a system of glass disks compressed along their diameters enables one to induce a doubly charged vortex beam in the emergent light when the incident light is circularly polarized. Using such a disk system, one can control the efficiency of conversion of the spin angular momentum to the orbital angular momentum by a loading force. The consideration presented here can be extended for the case of crystalline materials with high optical damage thresholds in order to induce high-power vortex beams.

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.

We have shown that a high-accuracy torsion method recently developed by the authors for measuring piezo-optic coefficients allows determining not only the absolute value of the coefficients but also their sign. The techniques and experimental procedures used for determination of the sign are described in detail and proven based on studies of α-BaB2O4 and LiNbO3 crystals. The piezo-optic coefficients are determined for both crystals, and a combination of the corresponding photoelastic coefficients is determined for the case of α-BaB2O4 crystals.