Silicon slow-light-based photonic mixer for microwave-frequencyconversion applications

This paper was published in OPTICS LETTERS and is made available as an electronic reprint with the permission of OSA. The paper can be found at the following URL on the OSA website: http://dx.doi.org/10.1364/OL.37.001721. Systematic or multiple reproduction or distribution to multiple locations via electronic or other means is prohibited and is subject to penalties under law[EN] We describe and demonstrate experimentally a method for photonic mixing of microwave signals by using a silicon electro-optical Mach¿Zehnder modulator enhanced via slow-light propagation. Slow light with a group index of ~11, achieved in a one-dimensional periodic structure, is exploited to improve the upconversion performance of an input frequency signal from 1 to 10.25 GHz. A minimum transmission point is used to successfully demonstrate the upconversion with very low conversion losses of ~7¿¿dB and excellent quality of the received I/Q modulated QPSK signal with an optimum EVM of ~8%.Financial support from FP7-224312 HELIOS project and Generalitat Valenciana under PROMETEO-2010-087 R&D Excellency Program (NANOMET) are acknowledged. F. Y.Gardes, D. J. Thomson, and G. T. Reed are supported by funding received from the UK EPSRC funding body under the grant “UK Silicon Photonics.” The author A. M. Gutiérrez thanks D. Marpaung for his useful help.Gutiérrez Campo, AM.; Brimont, ACJ.; Herrera Llorente, J.; Aamer, M.; Martí Sendra, J.; Thomson, DJ.; Gardes, FY.... (2012). Silicon slow-light-based photonic mixer for microwave-frequencyconversion applications. Optics Letters. 37(10):1721-1723. https://doi.org/10.1364/OL.37.001721S17211723371

All Optical Up-Conversion of WLAN signal in 60 GHz Range with Side-Band Suppression

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Direct Fluorescence Monitoring of Coal Organic Matter Released in Seawater

International audienceWhenever immersed in seawater after a collier accident, a fossil fuel such as coal could become a source of pollution to the marine environment. To study the effect of such a contamination, four coal samples from different origins were used. A first analysis on those coals enabled us to determine the content of polycyclic aromatic hydrocarbons. Seawater was then mixed with coal to study the organic matter released from coal into seawater. Fluorescence was used for its sensitivity to aromatic compounds, with the additional purpose of evaluating the relevance of using an immersed fluorescence probe to monitor water pollution. Excitation-emission matrices were recorded and the excitation-emission wavelength range corresponding to the highest fluorescence intensity was 230 nm/[370 nm; 420 nm]. The samples with coal happened to fluoresce more than the coal-free samples, the difference depending on the coal origin. The fluorescence intensity increased with coal mass, up to some limit. The particle size also influenced the fluorescence intensity, the finest particles releasing more fluorescing substances, due to their higher exchange surface. When seawater percolated through coal, the samples fluoresced highly at the beginning, and then the fluorescence intensity decreased and reached the seawater level. However, even with a 10 ns acquisition time shift, the fluorescence spectra were not specific enough to show the presence of PAHs in the samples, which were too diluted to be detected, whenever released from coal into seawater. The lifetimes of the seawater and of the coal samples were respectively 4.7 and 3.8 ns, indicating that the substances released from coal mainly consisted of short-lived fluorescing substances, such as natural humic or fulvic substances. Consequently, the presence of coal does not seem to be too detrimental to the marine environment, and a direct fluorescence probe could be used to monitor the seawater organic charge increase due to the immersion of coal in seawater

Imaging Time-Resolved Electrothermal Atomization Laser-Excited Atomic Fluorescence Spectrometry for Determination of Mercury in Seawater

International audienceIn this study, direct determination of mercury at the nanogram per liter level in the complex seawater matrix by imaging time-resolved electrothermal atomization laser-excited atomic fluorescence spectrometry (ITR-ETA-LEAFS) is described. In the case of mercury, the use of a nonresonant line for fluorescence detection with only one laser excitation is not possible. For measurements at the 253.652 nm resonant line, scattering phenomena have been minimized by eliminating the simultaneous vaporization of salts and by using temporal resolution and the imaging mode of the camera. Electrothermal conditions (0.1 M oxalic acid as matrix modifier, low atomization temperature) have been optimized in order to suppress chemical interferences and to obtain a good separation of specific signal and seawater background signal. For ETA-LEAFS, a specific response has been obtained for Hg with the use of time resolution. Moreover, an important improvement of the detection limit has been obtained by selecting, from the furnace image, pixels collecting the lowest number of scattered photons. Using optimal experimental conditions, a detection limit of 10 ng L–1 for 10 μL of sample, close to the lowest concentration level of total Hg in the open ocean, has been obtained

Incorporation of a ferrocene unit in the π-conjugated structure of donor-linker-acceptor (D-π-A) chromophores for nonlinear optics (NLO)

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Peamacléine Pru p 7 : épidémiologie, implications cliniques et place dans le diagnostic moléculaire de l’allergie à la pêche en région méditerranéenne

International audienceMolecular-based allergy diagnostic kits using standard IgE reagents such as peach extract, Pm p 1 (PR-10), Pru p 3 (non-specific lipid transfer protein), Pru p 4 (profilin), and cross-reactive carbohydrate determinants, are unable to identify the offending allergen in certain patients with peach allergy in Southern France, despite positive skin tests and a convincing clinical history. The constant and high positivity of the basophil activation test with peach extract in such patients suggests the involvement of a molecular peach allergen not included in existing in vitro diagnostic kits. Herein we report that peamaclein (Pm p 7) is a major allergen in peach-allergic patients in the Mediterranean (Marseille) region and we describe the epidemiological, clinical and laboratory characteristics associated with this novel allergen. (C) 2017 Published by Elsevier Masson SAS.Certaines allergies immédiates à la pêche ne sont pas élucidées sur le plan moléculaire par l’exploration des IgE spécifiques utilisées en routine : extrait de pêche, Pru p 1 (PR-10), Pru p 3 (protéine de transfert lipidique), Pru p 4 (profiline) et groupements glucidiques à réactivité croisée, et ce malgré des tests cutanés fortement positifs et une histoire clinique convaincante. L’exploration de ces patients par un test d’activation des basophiles en présence d’extrait de pêche est fortement positive, suggérant l’implication d’un allergène moléculaire de la pêche, absent des outils diagnostiques in vitro actuels. Nous rapportons ici la forte prévalence de la sensibilisation vis-à-vis de la peamacléine (Pru p 7) chez les patients méditerranéens allergiques à la pêche (région de Marseille), ainsi que les caractères épidémiologiques, cliniques et biologiques associés à ce nouvel allergène