S. M. Shandarov

Periodic domain structures formed under electron-beam irradiation in LiNbO3 plates and Ti:LiNbO3 planar waveguides of the Y cut

Regular domain structures on the Y cuts of the LiNbO3 substrates and Ti:LiNbO3 waveguide structures based on these substrates have been fabricated under electron-beam irradiation. It has been revealed that the domains in undoped and titanium-doped LiNbO3 crystals are formed as a result of different processes. It has been demonstrated using chemical etching and waveguide second-harmonic generation that regular domain structures in the Ti:LiNbO3 waveguides are formed at a depth of approximately 8 μm from the surface, where the titanium concentration does not exceed 2 mol %. The quasi-synchronous waveguide optical second harmonic generation with an efficiency of 8.8% has been obtained using the fabricated structures.

Light-induced absorption in a Bi12TiO20 crystal

Evolution of the light-induced absorption in a Bi12TiO20 crystal is investigated at a wavelength of 633 nm. It is found that the absorption coefficient evolution consists of fast and slow components with different characteristic response time. The light absorption coefficient decreases from 0.9 to 0.16 cm-1 after keeping the sample in darkness for six months. We propose a new charge-transport model that includes the deep donors in three valence states and the shallow traps. It is shown that the theory developed provides an explanation for the observed features of the increase and dark decay of the light-induced absorption. The material parameters of the Bi12TiO20 crystal are estimated from the best fit of the theoretical model with the experimental data.

Two-beam coupling in sillenite crystals

We present the results of a study of two-beam mixing and light-induced absorption in sillenite crystals at wavelength (lambda) equals 633 nm. We have employed the single-carrier model of the photorefractive effect with shallow and deep traps to the explanation of the experimental results.

Detection of the contribution of the inverse flexoelectric effect to the photorefractive response in a bismuth titanium oxide single crystal

Relations determining the contribution of the inverse flexoelectric effect to the photorefractive response have been determined for the case of the interaction of a steady pump wave conserving left-hand circular polarization with a phase-modulated signal wave that has circular polarization of the opposite sign on the input face of a crystal that has the (100) orientation and symmetry group 23. The experimental studies of such an interaction in a Bi12TiO20:Fe,Cu crystal make it possible to estimate its flexoelectric coefficient as f11 = 5.3 nC/m.

Photorefractive properties of doped sillenite crystals

We present a technology of a growing of pure and doped sillenite crystals and the results of a study of two-beam mixing in these crystals at wavelength (lambda) equals 633 nm. We have employed the single-carrier model of the photorefractive effect with shallow and deep traps to the explanation of the experimental results.

Nonunidirectional two-beam interaction in photorefractive bismuth silicate in an alternating electric field

The effective nonunidirectional energy exchange between like-polarized light beams is investigated experimentally on a photorefractive grating formed by diffusion drift in a bismuth silicate crystal placed in an alternating external electric field.

Polarization Effects at Two-Beam Interaction on Reflection Holographic Gratings in Sillenite Crystals

The polarization structure of the signal wave that interacts with a circularly polarized pump wave on the reflection holographic gratings in the (112)-, (111)-, and (110)-cut Bi12TiO20 (BTO) crystals is experimentally and theoretically analyzed. An analytical expression for the vector field of the signal wave that is valid for an arbitrary orientation of the cubic refractive crystal is derived using approximation of the nondepleting circularly polarized pump wave. The contribution of the absorption component of the reflection hologram into the counter interaction is estimated for the crystals under study using the approximation of the experimental data with theoretical curves. Based on the experiments with incoherent quasi-monochromatic radiation, it is demonstrated that the real BTO crystals exhibit weak induced linear birefringence.

Light wave diffraction on reflection holograms in a cubic piezoelectric crystal

AbstractAnalytical expressions for the electric field strength in a signal wave formed during the interaction of opposite waves in a cubic photorefractive piezoelectric crystal are obtained in the given grating approximation. As a result of the optical activity of the medium, the amplification coefficient and the diffraction efficiency of a hologram in the

Mixed transmission holograms in a Bi12TiO20 photorefractive crystal

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