Miniaturization and embedding of soliton-based electro-optically addressable photonic arrays

Using top-electrodes, we demonstrate the soliton-based miniaturized integration of electro-optic devices in a photorefractive paraelectric bulk crystal. Self-trapping and beam manipulation though soliton electro-activation is achieved at quasi-digital voltages

Dark current spectroscopy of transition metals in CMOS image sensors

We have investigated the effects of deliberate heavymetals contamination on dark current and image defects in CMOS Image Sensors (CIS). Analysis of dark current in these imager dice has revealed different behaviors among most important 3d metals present in the process line. We have implanted directly in 3 Mega array pixels the following metals: Cr, V, Cu, Ni, Fe, Ti, Mo, W, Al and Zn. Analyzing the dark current "spectrum" as obtained for fixed integration periods of time by means of standard image-Testing equipment, these impurities can be identified and detected with a sensitivity of ∼ 109 traps/cm3 or higher

Helicobacter pylori clarithromycin resistance assessment: are gastric antral biopsies sufficient?

Gastric biopsy ssampling could affect accuracy of Helicobacter pylori clarithromycin resistance assessment due to coexistence of susceptible and resistant strains (i.e. heteroresistance) either in same gastric site (intraniche) or in two different gastric sites (interniche). This study aimed to assess differences in the H. pylori clarithromycin resistance prevalence in relation to the gastric biopsy sampling by using Taqman-real time polymerase chain reaction (PCR). The study enrolled 137 patients. Primary clarithromycin resistance was observed in 15 isolates exclusively in antrum, in 7 cases exclusively in gastric body, and in 3 patients in both gastric sites. The overall prevalence of clarithromycin resistance was 13.1% by using exclusively antral biopsies, and 18.2% by using biopsies from both gastric sites. Moreover, intra-niche heteroresistance was observed in 19 (76%) out of 25 patients harbouring resistant strains. Our data found a heterogeneous distribution of resistant H. pylori strains in the stomach. Similarly to culture, gastric biopsies from both antrum and gastric body are needed to increase the accuracy of PCR-based methods for clarithromycin resistance assessment

Mechanisms supporting long propagation regimes of photorefractive solitons

We extend investigation of one-dimensional solitons in biased photorefractive crystals to long propagation regimes, where self-trapping over a large number of linear diffraction lengths combines with the progressive growth of generally distortive spatially nonlocal components. Results indicate that saturation halts the radiative misshaping of the soliton, which follows that specific bending trajectory along which its evolution is governed by the same local screening nonlinearity that intervenes in short propagation conditions, where spatial nonlocality has a negligible effect. This finding not only allows the prediction of the curvature and of the relative role of charge displacement and diffusion, but implies a set of interesting observable effects, such as boomerangs, counterpropagating and cavity geometries, quasirectilinear and anomalous collisions, along with specific consequences on soliton arrays and on coupling to bulk gratings

Emergence of linear wave segments and predictable traits in saturated nonlinear media

We find the key behind the existence traits of asymptotic saturated nonlinear optical solitons in the emergence of linear wave segments. These traits, produced by the progressive relegation of nonlinear dynamics to wave tails, allow a direct and versatile analytical prediction of self-trapping existence conditions and simple soliton scaling laws, which we confirm experimentally in saturated-Kerr self-trapping observed in photorefractives. This approach provides the means to correctly evaluate beam tails in the saturated regime, which is instrumental in the prediction of soliton interaction forces. © 2003 Optical Society of America