LiNbO3 ridge waveguides realized by precision dicing on silicon for high efficiency second harmonic generation

Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only use of a precision dicing machine without need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. Influence of geometrical non uniformities of waveguides due to fabrication process is asserted. Components characteristics are studied notably their robustness and tunability versus temperature.Comment: 10 pages, 10 figure

Crustal shortening and vertical strain partitioning in the Middle Atlas Mountains of Morocco

Copyright 1998, American Geophysical Union. See also: http://www.agu.org/pubs/crossref/1998/98TC01439.shtml; http://atlas.geo.cornell.edu/morocco/publications/gomez1998.htmThe NE-SW trending Middle Atlas Mountains of Morocco are obliquely oriented within the late Cenozoic regional stress field, resulting in deformation that is partitioned into strike-slip faulting and thrust-related folding. In the central Middle Atlas, thrusting is confined to a 20 km wide fold belt between two relatively rigid crustal blocks that are obliquely converging. We suggest that in addition to strain partitioning observed in plan view, a partitioning of deformation between the upper and lower crust may be necessary to reconcile estimated crustal thickening and horizontal shortening within the fold belt. Cross-section balancing based on field observations demonstrates a relatively modest amount of Cenozoic horizontal shortening (~ 4.7 km) normal to the fold belt producing 800 m of structural relief. Yet, the geophysical data suggest this contraction has not produced a significant crustal root beneath the fold belt; that is, the belt does not appear to be isostatically compensated. Assuming all horizontal shortening was accommodated by crustal thickening beneath the fold belt implies much greater thickening than is suggested by constraints on the preshortened crustal thickness. It thus appears that thickening does not accommodate all of the contraction. We suggest one possible solution: The upper crust shortens by thickening (faulting and folding), whereas the lower crust deforms laterally

Combining scanning probe microscopy and x-ray spectroscopy

A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented

Volumetric Properties of Binary Mixtures of 1,2-Dichloroethane with Polyethers from (283.15 to 333.15) K and at Atmospheric Pressure

This article is part of the John M. Prausnitz Festschrift special issue.International audienceDensities of binary liquid mixtures of 1,2-dichloroethane (1,2-DCE) with ethylene glycol dimethyl ether (EGDME), diethylene glycol dimethyl ether (DEGDME), and diethylene glycol diethyl ether (DEGDEE) were measured at temperatures from (283.15 to 333.15) K and at atmospheric pressure, over the whole composition range, with an Anton Paar vibrating-tube densimeter. Excess molar volumes, VE, were deduced from experimental densities and were fitted to the Redlich−Kister polynomial equation. The VE values, for all these mixtures, are negative over the entire composition and temperature ranges. Values of VE magnitude for mixtures of 1,2-DCE with EGDME or DEGDME are close and increase slightly as the temperature increases, whereas those for 1,2-DCE + DEGDEE decrease and are more important. Others volumetric properties such as thermal expansion coefficients, excess thermal expansion, partial molar volumes, apparent molar volumes, and partial molar excess volumes were also calculated. Composition and temperature dependences of VE/x1x2 were explored. The capability of the Prigogine−Flory−Patterson theory (PFP) to model the VE data, at T = 298.15 K, for the binary mixtures studied, was finally tested

Periodically poled LiNbO3 ridge waveguides on silicon for second harmonic generation

International audienceNonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are micromachined with a precision dicing machine and/or by grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 600%/W in a 20mm long device. Influence of geometrical non uniformities of waveguides due to fabrication process is asserted. Components characteristics are studied notably their robustness and tunability versus temperature