L. I. Ivleva

Raman spectroscopy of crystals for stimulated Raman scattering

Abstract Raman frequency shift, line width, integral and peak Raman scattering cross sections were measured in various crystals using spontaneous Raman spectroscopy. The highest Raman gain coefficient in steady state Stimulated Raman Scattering (SRS) regime was proved to be in barium nitrate crystal; for transient SRS it is expected to be in lithium niobate and tungstate crystals. Barium molybdate crystal is proposed as a new highly efficient Raman material. OCIS : 300.6450; 290.5910; 190.2640

SrWO4 :Nd3+: new material for multifunctional lasers

Abstract Results on the growth technique, spectral and luminescence characteristics of Nd3+ ions in SrWO4 Raman crystals are presented. Optimal conditions to obtain optically homogeneous single crystals free of light scattering centers and growth striations were found. The values of effective segregation coefficients of active Nd and compensating Nb ions were determined. Strontium tungstate crystal exhibits one of the highest Raman gain values (5.0 cm/GW) among Nd-doped Raman host materials. Efficient intracavity Raman self-conversion in Nd3+:SrWO4 laser was demonstrated.

Growth of SBN single crystals by Stepanov technique for photorefractive applications

Abstract The Stepanov technique has been developed for SBN solid-solution crystal growth. We carried out a comparison of the growth conditions of SBN crystals in the traditional Czochralski method and new growing technique. The advantages of the Stepanov technique for growing of pure and doped SBN crystals are shown. They are high optical quality; definite form and sizes. High effective DPCM and high effective SPPCM were realized for SBN crystals doped with Ce. It was demonstrated that SBN doped with Cr and Co are promising photorefractive materials with short response time.

Insulating material: growth and characterizationGrowth of SBN single crystals by Stepanov technique for photorefractive applications

Abstract The Stepanov technique has been developed for SBN solid-solution crystal growth. We carried out a comparison of the growth conditions of SBN crystals in the traditional Czochralski method and new growing technique. The advantages of the Stepanov technique for growing of pure and doped SBN crystals are shown. They are high optical quality; definite form and sizes. High effective DPCM and high effective SPPCM were realized for SBN crystals doped with Ce. It was demonstrated that SBN doped with Cr and Co are promising photorefractive materials with short response time.

Ferroelectric properties of strontium barium niobate crystals doped with rare-earth metals

The influence of doping of the SrxBa1−xNb2O6 (x=0.61) crystals (SBN-0.61) by rare-earth element (RE) dopants has been investigated. Taking into account the data available in the literature, it is demonstrated that the introduction of all rare-earth metals is accompanied by a substantial decrease in the temperature of the phase transition Tp and an increase in its smearing. The shift in the Tp temperature for certain rare-earth metals ranges up to 20 K per atomic percent of dopant in the crystal. It is experimentally established that, in the SBN-0.61: Yb, SBN-0.61: Ce, SBN-0.61: Tm, SBN-0.61: La, and SBN-0.61: (Ce + La) crystals, a decrease in Tp brings about a considerable increase in the permittivity and the piezoelectric and electrooptical coefficients. The conclusion is drawn that the doping by rare-earth metals provides a means of optimizing the properties of strontium barium niobates. The pulse switching of the SBN-0.61 and SBN-0.61: RE crystals is studied for the first time. It is found that the switching is characterized by a number of features, the most important of which is a decrease in the switched charge after the application of external fields. This effect associated with the specific features of the switching in the relaxor ferroelectric is assumed to be responsible for the instability of the parameters for strontium barium niobate material.

Atomic structure of Sr0.75Ba0.25Nb2O6 single crystal and composition-structure-property relationin (Sr,Ba)Nb2O6 solid solutions

The structure of the Sr0.75Ba0.25Nb2O6 single crystal has been investigated by x-ray diffraction. The occupancies of the Ba and Sr sites in two structural channels are determined. It is found that these sites are split in the large (pentagonal) channel. A qualitative correlation is revealed between the smearing of the phase transition and the displacement of the Sr atom from the m symmetry plane in the pentagonal channel at different [Sr]/[Ba] ratios. The degree of acentricity of the NbO6 octahedra is analyzed as a function of the [Sr]/[Ba] ratio.

Growth and properties of ZnMoO4 single crystals

The crystallization conditions for obtaining zinc molybdate single crystals by the Czochralski and Kyropoulos methods from a melt have been studied. The growth parameters of large single crystals of optical quality are determined. The physicochemical and spectral-luminescent characteristics of the single crystals are studied.

Double phase-conjugate mirror: experimental investigation and comparison with theory

An experimental investigation of the geometry of a double phase-conjugate mirror in a photorefractive strontium barium niobate crystal is carried out. A shift of the transverse intensity distributions of scattered beams with respect to those of pump beams and a sublinear dependence of the scattered-beam power ratio on the power ratio of the pump beams are observed. The experimental results are interpreted on the basis of a two-dimensional model that accounts for both four-wave mixing and fanning.

Effects of rare-earth impurity doping on the ferroelectric and photorefractive properties of strontium–barium niobate crystals

Abstract Doping strontium–barium niobate (SBN) crystals with rare earth (RE) impurities strongly lowers the ferroelectric phase transition T c which results in a significant enhancement of the dielectric permittivity and electrooptic coefficients and in a simultaneous decrease of the coercive field E c . In photorefractive SBN:Ce crystals co-doped with a non-photorefractive impurity La we studied the hysteresis dependence of the two-beam coupling gain Γ on the external field.

Ferroelectric microdomains and microdomain arrays recorded in strontium–barium niobate crystals in the field of atomic force microscope

Microdomains and various one-dimensional (1D)- and two-dimensional (2D)-microdomain arrays were formed under dc-voltages applied to the tip of an atomic force microscope (AFM) in ferroelectric SrxBa1−xNb2O6 crystals. Detailed studies of the characteristics of the AFM—recording and decay kinetics of the written arrays have shown that the crucial factors of the stability of a domain array are its dimensionality and discreteness (described by a distance Δ between the recorded point domains forming the array). The dependence of the stability on the discreteness of domain ensembles is analyzed. With decreasing Δ, the decay times of the domain ensembles increases. The stability of 2D arrays (domain squares, complex-shaped arrays composed of the domain ensembles of opposite polarity) by orders of magnitude exceeds that of 1D-arrays (domain chains and lines) provided all factors of recording being the same. As an illustration, the decay time of individual (spatially separated) domains and quasicontinuous domain l...