Manifestation of circular photogalvanic current by dynamic holography in BaTiO3

We report the first measurement of the photo-galvanic circular current antisymmetric tensor component in BaTiO₃: Co. The measurement gives a value of this coefficient, for extraordinary beam amplification, of 4×10^–9 A/W using a nonstationary measurement technique at a wavelength of 0.632 m.Professor N. Kukhtarev is on leave from the Institute of Physics in the Ukraine and is supported by the NSFDr. G. Dovgalenko is on leave from the IRPA Rotor-Control research laboratory of the Ukraine and is supported by the University of Arkansas     

Phase conjugation by reflection gratings in electrooptic crystals

Phase conjugation by reflection gratings in electrooptic crystals in investigated in a nonlinear model proposed by Kukhtarev and Semenets [1] which takes into account not only photoconductivity but also dark conductivity. The coupled-wave equations of the model can be solved analytically. To take the boundary conditions into account, numerical calculations are unavoidable. These can be performed, however, without any approximation. Phase mismatch and self-oscillation effects are dealt with in the undepleted pump approximation.Two of us (KHR and GT) would like to dedicate this paper to Prof. Dr. H. Salecker on the occasion of his 65^th birthday     

Influence of the optical activity on hologram formation in photorefractive crystals

It is shown that dynamical hologram formation in photorefractive, optically active crystals is accompanied by polarization and energy exchange. These effects may be used like new effective holographic methods for determinations of crystal parameters and optical signal processing in real time. In self-diffraction a polarization rotation the order of degrees/cm for Bi₁₂TiO₂₀ and Bi₁₂SiO₂₀ is predicted.     

Degenarate four-wave mixing in LiNbO3 and LiTaO3

Continuous wave generation of complex conjugate wavefront via four-wave mixing in LiNbO₃ and LiTaO₃ with diffusion non-linearity is studied. Strong anisotropy of the degenarate four-wave mixing is observed and explained.     

The shear modulus of the human vocal fold in a transverse direction

The aim of this study was to measure the shear modulus of the vocal fold in a human hemilarynx, such that the data can be related to direction of applied stress and anatomical context. Dynamic spring rate data were collected using a modified linear skin rheometer using human hemilarynges, and converted to estimated shear modulus via application of a simple shear model. The measurement probe was attached to the epithelial layer of the vocal fold cover using suction. A sinusoidal force of 3g was applied to the epithelium, and the resultant displacement logged at a rate of 1kHz. Force measurement accuracy was 20microg and position measurement accuracy was 4microm. The force was applied in a transverse direction at the midmembranous point between the vocal process and the anterior commissure. The shear modulus of the three female vocal folds ranged from 814 to 1232Pa. The shear modulus of the three male vocal folds ranged from 1021 to 1796Pa. These data demonstrate that it is possible to obtain estimates for the shear modulus of the vocal fold while preserving anatomical context. The modulus values reported here are higher than those reported using parallel plate rheometry. This is to be expected as the tissue is attached to surrounding structures, and is under natural tension.     

The theory of the carriers mobility in layer-inhomogeneous semiconductors

An effective mobility of the charge carriers is calculated in a diffusional approximation for a semiconductor with the uniaxial quasiperiodical distribution of the doping impurity, in a wide temperature interval including the regions of the weak and of the strong impurity ionisation. At the conditions when the compensation is significant in parts with minimal concentration of doping impurity, the influence of the non-uniformity of the distribution sharply increases. The effective mobility in the direction normal to the layers μ⊥ becomes essentially different in value and in the temperature dependence from the mobility along the layers. The extrema can appear in the dependence μ⊥(T).     

COMPOSITION OF INDOOR AEROSOLS AT EMPEROR QIN''''S TERRA-COTTA MUSEUM, XI''''AN, CHINA, DURING SUMMER, 2004

Particle samples were collected in August 2004 both inside and outside Emperor Qin's Terra-Cotta Museum in Xi'an, China. Mass and chemical composition of total suspended particles (JSP, particles with aerodynamic diameter less than-30μm), PM2.5(particles with aerodynamic diameter <2.5μm) were determined. The average levels of indoor PM2.5 and TSP were 108.4 and 172.4 μg·m-3, respectively, with PM2.5 constituting 62.9% of the TSP mass. Sulfate ((32.4±6.2)%), organics ((27.7±8.0)%), and geological material ((12.5±3.4)%) dominated indoor PM2.5, followed by ammonium ((8.9±2.8)%), nitrate ((7.0±2.9)%), and elemental carbon (EC, (3.9±1.5)%). Particle size distribution varied with the number of tourists in the museum. The size of sulfate, organics, EC, nitrate, and ammonium was found to vary in the range of 0.43 to 3.3 μm in fraction. Ion balance indicated that the aerosol was acidic, with insufficient ammonium ions to neutralize the sulfuric and nitric acids. High concentrations of acidic aerosols will erode the Terra-cotta warriors and horses especially in the summer season with high temperature (30℃) and relative humidity (70%) and undesirable solar radiation inside the museum. More attention should be paid to protecting these precious antiques made 2000 years ago.     

Image transmission via a multimode fiber assisted by polarization preserving phase conjugation in the photorefractive crystal

Image transmission via a 2m-long multimode fiber was realized by using polarization-preserving phase conjugation in the photorefractive crystal and correcting holograms.