Second-order nonlinear optical properties induced by thermal poling in photonic oxide glasses and transparent glass-ceramics

In recent years there has been a resurgence of interest in oxide glasses due to advances in lasers for information transport. Oxide glasses combine low cost of fabrication and good compatibility with silica glass fibers, which offer the opportunity for developing structures with nonlinear optical properties in integrated optical devices. The creation of an axial symmetry under thermal poling is currently necessary to induce Second-Order NonLinear (SONL) optical properties in glasses. A description of theoretical models which have been proposed for charge migration during thermal poling is presented. A review of SONL efficiencies which have been obtained for different glass compositions by this method is reported. Correlations between SONL properties and structural modifications under poling are also presented. Finally, we focus on the challenging fabrication of transparent glass-ceramic composites, especially when they are obtained by the precipitation of ferroelectric nanoparticle phases in the glassy matrix which adds the advantageous SONL properties of ferroelectric crystals

Demonstration Of Dimensional Control And Stabilization Of Second Harmonic Electrooptical Response In Chalcogenide Glasses

Second-order optical susceptibility, χ(2), has been induced in thermally poled chalcogenide glasses, doped with varying levels of sodium. Using alkali-doped chalcogenide glasses, the second harmonic generation (SHG) capability is retained for over a year whereas in alkali-free glasses it disappears in days. The enhanced stability is attributed to a stabilization of the space charge through structural re-arrangements. Polarization-resolved SHG shows that the induced electric field has components in three spatial directions, all with varying extents of stability. Using structured electrodes, we demonstrate the ability to control the various electric field components\u27 geometry, location and stability to realize a long-lived, nonlinear grating in an alkali-doped chalcogenide glass

Gas chromatographic-mass spectrometric method for polycyclic aromatic hydrocarbon analysis in plant biota

International audienceUsing gas chromatography-mass spectrometry, a new method was developed for the identification and the quantification of polycyclic aromatic hydrocarbons (PAHs) in plants. This method was particularly optimised for PAH analyses in marine plants such as the halophytic species, Salicornia fragilis Ball et Tutin. The saponification of samples and their clean up by Florisil solid-phase extraction succeeded in eliminating pigments and natural compounds, which may interfere with GC-MS analysis. Moreover, a good recovery of the PAHs studied was obtained with percentages ranging from 88 to 116%. Application to the determination of PAH in a wide range of coastal halophytic plants is presented and validated the efficiency, the accuracy and the reproducibility of this method

Structural rearrangements and second-order optical response in the space charge layer of thermally poled sodium-niobium borophosphate glasses

Sodium-niobium borophosphate glasses have been thermally poled and studied in the mid- and far-infrared range to probe their possible structural rearrangements and to correlate them with the measured nonlinear optical (NLO) response. The infrared analysis of thermally poled and depoled glasses has revealed systematic structural changes in the NLO-active space charge layer at the anode on the basis of which we suggest that sodium ion migration from this layer is accompanied by an equivalent migration of oxide ions. Ion depletion in the NLO layer induces extensive, but partially reversible by depoling, modifications of the phosphate and niobate parts of the network that depend on the composition of the glass..

Measuring the biological impact of drilling waste on the deep seafloor: an experimental challenge

The depletion of traditional oil fields is driving the oil & gas industry to explore new exploitation sites previously considered as unprofitable. Deep-sea oil fields represent one of these new areas of exploitation. Well drilling during exploration and production operations generate large quantities of drilling waste whose biological impact on the deep-sea floor remains largely unknown. Because of the harsh abiotic factors characterizing this environment, the evaluation of this impact remains challenging. High hydrostatic pressure is the prominent factor which will affect in-situ biological processes. This review will examine the feedback on the various strategies used to evaluate the biological impact of deep-sea drilling waste deposition as well as the current technological limitations. Given the complexity of this issue, a good perspective strategy would be to trend towards the research and development of more relevant bioassays, especially considering the crucial factor of hydrostatic pressure

Fabrication of microcraters on silicon substrate by UV nanosecond photonic nanojets from microspheres

We report briefly on the fabrication of arrays of nano- and micro-craters on silicon (Si) substrates using films of C18 functionalized 1 μm silica (SiO2) particles deposited by the Langmuir-Blodgett (LB) technique. The films are illuminated with UV nanosecond laser pulses. Local substrate ablation is observed at low fluences well below the damage threshold of silicon (1 J/cm2). The result is quantitatively explained through FDTD simulations of the micro lensing effect associated with the microspheres. Change in feature size and morphology with number of shots and laser fluence is investigated. In multi-shot irradiation experiments, the produced arrays of well-defined craters rely on the combination of direct laser ablation and laser surface cleaning or annealing as evidenced by Atomic Force Microscopy (AFM) technique

Synthesis, structural and optical characterizations of tellurium oxide based glasses for optical devices : study of ionic mobility of alkaline metal under thermal poling

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