G. V. Kulak

Ultrasonic diffraction of Bessel light beams in uniaxial gyrotropic crystals

Specific features of the acousto-optic diffraction of Bessel light beams propagating in the vicinity of the optical axis of a uniaxial gyrotropic crystal have been investigated. The dependences of the diffraction efficiency on the acousto-optic interaction length, ultrasound power, and polarization state of the incident Bessel light beam have been analyzed using the coupled-wave equations and the overlap-integral method. It is shown that polarization-independent diffraction of Bessel light beams is observed in paratellurite crystals, when the Bragg diffraction efficiency is independent of the polarization state of the incident beam. The physical reason for this diffraction has been established (both theoretically and experimentally) to be simultaneous implementation of two processes of anisotropic scattering, at which the Bragg synchronism conditions are satisfied for orthogonal polarized Bessel beams with elliptical polarization.

Light diffraction on acoustophotorefractive holographic gratings

The intermediate regime of light diffraction on acoustophotorefractive holographic gratings written in cubic photorefractive crystals according to the synchronous-detection mechanism is studied. It is shown that the diffraction efficiency in sillenite-type gyrotropic crystals only slightly depends on the incident light polarization and the external electric field. The highest diffraction efficiency in nongyrotropic crystals was achieved for p-polarized writing and reading light and at a considerable external electric field strength.

Wideband light diffraction on bulk acoustic waves in uniaxial crystals

We study diffraction of light on ultrasonic waves, excited by a system of interdigitial transducers, in uniaxial crystals. We show that wideband acoustooptical diffraction in trigonal crystals in the presence of additional anisotropy differs significantly from the isotropy of diffraction on a shear ultrasonic wave in the absence of it. We establish that an exact Bragg angle correction in a wide frequency retuning range is achieved owing to electrically induced anisotropy in the external electric field.

Light diffraction on ultrasonic Love waves

It is shown that layers based on acoustooptic crystals excited by ultrasonic Love waves can be used as light modulators in the reflection and transmission mode. It is established that various modes of Love waves can be detected by optical methods. For small ultrasound intensities, the diffraction efficiency is determined by the degree of homogeneity of deformations within the layer, and for large intensities, by the length of the acoustooptic interaction.

Polarization-Independent Ultrasonic Modulation of Light in Gyrotropic Cubic Bismuth Germanate Crystals

An intermediate regime of light diffraction by ultrasound propagating along the [001] and [110] axes of a gyrotropic cubic bismuth germanate crystal is investigated. The possibility of polarization-independent light modulation in the intermediate regime of diffraction close to the Bragg regime is shown. The dependences of the diffraction efficiency on the incident light polarization azimuth at different ultrasonic wave intensities are given.