N. I. Burimov

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.

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.

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.

Surface periodic domain structures for waveguide applications

We report the results of fabrication and investigations of surface periodic domain structures created by a set of quasi-point e-beam irradiations both on the Y- and X-cuts of LiNbO3, and on Ti:LiNbO3 and Zn:LiNbO3 planar waveguides. Domain gratings with spatial periods from 4.75 to 7.25 μm were formed by a 25-keV e-beam. Doses from 500 to 2000 μC/cm2 were used for different structures to estimate optimal fabrication conditions. The investigations allowed the visualization of the formed surface domain structures, estimation of their uniformity, and determination of waveguide generation of the second optical harmonic. The surface structures can be used in optical devices for the realization of quasi-phasematched frequency conversion, which includes the creation of compact radiation sources based on waveguides.

Elastic and piezoelectric constants of Bi12TiO20 crystals

Abstract The elastic constants and piezoelectric coefficient of Bi 12 TiO 20 crystal have been determined. The material constants have been calculated from the experimental data of the phase velocities of acoustic waves at the acoustooptical interaction.

Planar Domain Gratings Fabricated by a Set of Local E-Beam Irradiations on the Y-Cuts of LiNbO3 and in the Planar Waveguide Ti:LiNbO3

The ferroelectric domains in Y-cut LiNbO3 were obtained by e-beam irradiations in the SEM. Due to a serial set of local irradiations, the planar domain gratings with period Λ = 3, 7 and 20 μm were fabricated and examined after chemical etching. The same technique was used for domain grating formations in Ti in-diffused Y-cut LiNbO3 optical waveguides. In the Ti:LiNbO3, domain gratings were located in the depth of the waveguide under the crystal surface. The best experimental conditions were used to record rows of gratings with Λ = 7 μm in Y-cut Ti:LiNbO3. The second harmonic generation on these planar gratings has been obtained.

Contribution from the inverse flexoelectic effect to the photorefractive response in a bismuth titanium oxide

Results from studying the contribution from inverse flexoelectric and photoelastic effects to the photorefractive response upon counter-wave interactions corresponding to the reflective holograms of (100)-cut sillenite single crystals are reported. A stationary reference wave with circular polarization and a phase-modulated signal wave were used in obtaining the holograms.

Anisotropy of Acoustic Wave Velocities and Electromechanical Coupling Coefficients in the Crystals of Symmetry mm2 and 4mm

Results of the theoretical and numerical analysis of orientation dependences for velocities and electromechanical coupling coefficients (EMCC) KD and KE for the longitudinal and shear acoustic waves propagating in the (100), (010) and (001) crystallographic plane of the crystals with symmetry mm2 and 4mm are presented. We have obtained that the EMCC KE and KD are comparable to their value in every from these crystals. The optimal conditions for surface excitation of acoustic waves in these crystals were found.

Surface structure of photorefractive grating in KNbO 3

It is known that localized elastic and electric fields appear near the surface of piezoelectric crystals under photorefractive grating information.

Photorefractive surface grating m BaTi0 3

Photorefractive phenomena near the surface of a crystal are of great interest to the applications such as fast phase conjugation, amplification of optical signals, optical information processing [1,2].