Comparative analysis of ferroelectric domain statistics via nonlinear diffraction in random nonlinear materials.

We present an indirect, non-destructive optical method for domain statistic characterization in disordered nonlinear crystals having homogeneous refractive index and spatially random distribution of ferroelectric domains. This method relies on the analysis of the wave-dependent spatial distribution of the second harmonic, in the plane perpendicular to the optical axis in combination with numerical simulations. We apply this technique to the characterization of two different media, Calcium Barium Niobate and Strontium Barium Niobate, with drastically different statistical distributions of ferroelectric domains.

Single ketamine infusion and neurocognitive performance in bipolar depression.

We estimated neurocognitive performance using the trail making test (TMT) and the Stroop color-word interference test before, and on the 3(rd) day after a single infusion of ketamine, in 18 bipolar depressed patients receiving mood-stabilizing drugs. The performance on all tests significantly improved on the 3(rd) day after ketamine infusion which correlated positively with baseline intensity of neuropsychological impairment and was not associated either with baseline intensity of depression or reduction of depressive symptoms after 3 or 7 days. The results suggest that in such population of patients, single ketamine infusion may improve neuropsychological performance independently of antidepressant effect.

UV-induced nonlinear absorption in lanthanum calcium borate single crystals.

It has been revealed that lanthanum calcium borate (La2CaB10O19) crystals show two-photon absorption (TPA) induced by a UV laser field. UV-induced TPA measurements were performed in the spectral range of 475-1130 nm using as fundamental beam the third harmonics of the 28 ps Nd-YAG pulsed laser as a pumping beam for LiB3O5 optical parametrized generator using Z-scan method. Investigations performed by the Z-scan method were done during illumination by a Xe-F laser (lambda = 217 nm) as a photoinducing (pumping) beam. The pumping laser beam created a thin surface layer (about 80-90 nm) that was the source of the observed photoinduced TPA. The highest values of the TPA beta coefficients were achieved for polarization of the pumping light directed along the second-order crystallographic axis of the investigated crystals. The obtained values of the TPA coefficients were higher than those for the BiB3O6 crystals investigated earlier by us.