Determination of refractive index, thickness, and the optical losses of thin films from prism-film coupling measurements

International audienceWe present a method of analysis of prism-film coupler spectroscopy based on the use of transfer matrix and genetic algorithm, which allows the simultaneous determination of refractive index, thickness, and optical losses of the measured layer

Optical characterization of PZT thin films for waveguide applications

International audienceIn order to develop an electro-optic waveguide, Pb(Zr, Ti)O3 ceramic ferroelectric thin films were elaborated by a modified sol-gel process on glass substrate. In the aim to study the optical properties of the PZT films, an accurate refractive index and thickness measurement apparatus was set up, which is called M-lines device. An evaluation of experimental uncertainty and calculation of the precision of the refractive index and thickness were developed on PZT layers. Two different processes of PZT elaboration were made and studied with this apparatus. The reproducibility of one fabrication process was tested and results are presented in this paper

Millington Effect and Propagation Enhancement in 60-GHz Body Area Networks

International audienceMillington effect for on-body propagation enhancement is presented in the 60-GHz band. Millington’s equations are developed to describe propagation above a flat inhomogeneous surface. This study focuses on mixed paths (human skin - metallic) for on-body scenarios. It is shown that adding metallic paths on the human skin can improve the power link budget between two nodes placed on the body. Two different schemes are studied experimentally to assess the analytical model using a flat phantom with electric properties of human skin and different lengths of metallic inserts. The first scheme considers a metallic plate between the transmitting and receiving antennas, while the second scheme proposes locating the metallic plates under the antennas. It is shown that the second scheme yields a better link budget than the first one for the same length of metal. Moreover, a numerical study is performed to assess the impact of the following different parameters: the location of the metal plate, size of the plate and the height of the antennas. Excellent agreement between numerical and experimental results has been shown. In the best cases, the presented techniques allow to improve the path loss of 10 to 20 dB

Isostasie postglaciaire différentielle au lac-Saint-Jean (Québec) et implications sur la qualité de l’eau souterraine

Cette étude présente d’abord le pourtour complet du maximum marin (mer de Laflamme) au Lac-Saint-Jean (Québec) et la position du premier rivage lacustre développé pendant la remontée isostatique postglaciaire qui se poursuit toujours. Suit une discussion de l’origine possible des eaux salines diluées, localement présentes au Lac-Saint-Jean : eau marine postglaciaire, eaux sous glaciaires et vieilles eaux profondes du Bouclier canadien. This study describes first the complete outline of the highest marine level in the Lac-Saint-Jean area (Québec) as well as the position of the first shoreline of the fresh water lake that replaced the Laflamme sea during the last post glacial uplift (still ongoing). Then, the possible origin of the dilute salty waters found here and there in the Lac-Saint-Jean area is discussed: post glacial sea water, sub-glacial waters and deep Canadian Shield old waters