Cso Stati Uniti

Padova, Italy

Cso Stati Uniti

Padova, Italy
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Ruffato G.,University of Padua | Ruffato G.,Cso Stati Uniti | Massari M.,University of Padua | Massari M.,Cso Stati Uniti | And 3 more authors.
Optics Letters | Year: 2017

The orbital angular momentum (OAM) of light has recently attracted a growing interest as a new degree of freedom in order to increase the information capacity of today's optical networks, both for free-space and optical fiber transmission. Here we present our work of design, fabrication, and optical characterization of diffractive optical elements for compact OAM mode division demultiplexing based on optical transformations. Samples have been fabricated with 3D high-resolution electron beam lithography on a polymethylmethacrylate resist layer spun over a glass substrate. Their high compactness and efficiency make these optical devices promising for integration into next-generation platforms for OAM modes processing in telecom applications. © 2017 Optical Society of America.


Ruffato G.,University of Padua | Ruffato G.,Cso Stati Uniti | Massari M.,University of Padua | Massari M.,Cso Stati Uniti | And 4 more authors.
Optics Express | Year: 2017

In recent years, mode-division multiplexing (MDM) has been proposed as a promising solution in order to increase the information capacity of optical networks both in free-space and in optical fiber transmission. Here we present the design, fabrication and test of diffractive optical elements for mode-division multiplexing based on optical transformations in the visible range. Diffractive optics have been fabricated by means of 3D high-resolution electron beam lithography on polymethylmethacrylate resist layer spun over a glass substrate. The same optical sequence was exploited both for input-mode multiplexing and for output-mode sorting after free-space propagation. Their high miniaturization level and efficiency make these optical devices ideal for integration into next-generation platforms for mode-division (de)multiplexing in telecom applications. © 2017 Optical Society of America.


Ruffato G.,University of Padua | Massari M.,University of Padua | Romanato F.,University of Padua | Romanato F.,Cso Stati Uniti | Romanato F.,INFM TASC IOM National Laboratory
IET Conference Publications | Year: 2016

We present the design, fabrication and optical characterization of compact phase-only diffractive optical elements (DOE) for the (de)multiplexing of beams carrying orbital angular momentum (OAM) of light, engineered for integration into next-generation OAM-based optical platforms. Samples have been fabricated with high-resolution electron-beam lithography on polymethylmethacrylate (PMMA) resist layer spun over a glass substrate and the high quality has been inspected with atomic force microscopy (AFM) and scanning electron microscopy (SEM). Various designs are presented for the sorting of optical vortices differing in either OAM content or beam size, with several steering geometries in far-field. The optical characterization has been performed at the selected wavelength ?=632.8 nm in terms of channel efficiency and inter-channel cross-talk, exhibiting remarkable optical performance.


Belmokhtar S.,Abdelmalek Essaadi University | Bouajaj A.,Abdelmalek Essaadi University | Britel M.R.,Abdelmalek Essaadi University | Normani S.,CNR Institute for Photonics and Nanotechnologies | And 8 more authors.
Proceedings of 2015 IEEE International Renewable and Sustainable Energy Conference, IRSEC 2015 | Year: 2015

The efficiency of semiconductor solar cells may be improved by inserting in the front or rear of the solar cell an optically active layer doped with rare earth ions which acts as «down-converter» (DC) or «up-converter» (UC). This is just one of the possibilities that involve several structures and geometries such as waveguide configuration and radiation trapping systems. Among these systems glass ceramics play a crucial role especially because they combine the optical properties of glasses with the spectroscopic properties of the crystals activated by luminescent species. In this work we will give a short review regarding the research already performed by the team in the field of down-conversion process. We will focus the attemption on the cooperative energy transfer between donor and acceptor ions taking as example the interaction among one Tb3+ ion and two Yb3+ ions allowing to cut one high energy photon at wavelength shorter than 488 nm into two low energy photons around 980 nm. The choice of the matrix is another crucial point to obtain an efficient down conversion processes with rare earth ions; we demonstrated that the Tb3+/Yb3+ energy transfer efficiency in a 70SiO2-30HfO2 glass-ceramic waveguide is effective. © 2015 IEEE.


Belmokhtar S.,Abdelmalek Essaadi University | Bouajaj A.,Abdelmalek Essaadi University | Britel M.,Abdelmalek Essaadi University | Normani S.,CNR Institute for Photonics and Nanotechnologies | And 6 more authors.
Journal of Materials and Environmental Science | Year: 2016

The aim of this paper is to study the possibility to improve the efficiency of solar cells by using downconversion of high energy photons into low energy ones thanks to the Tb3+/Yb3+ energy transfert mechanism in 70SiO2-30HfO2 glass-ceramic waveguides. The preparation of the waveguides by a sol-gel method is first presented. Then results of compositional and optical (Photoluminescence) characterization are given. The result found is that the transfer efficiency is about 38% for the sample with the highest concentration of rare earths (5%).


Belmokhtar S.,Abdelmalek Essaadi University | Bouajaj A.,Abdelmalek Essaadi University | Britel M.,Abdelmalek Essaadi University | Normani S.,CNR Institute for Photonics and Nanotechnologies | And 6 more authors.
Lecture Notes in Electrical Engineering | Year: 2016

A down-conversion layer placed on the front side of silicon solar cells waveguides has the potential to cute one high-energy photon into two low energy photons. This paper examines the Tb3+/Yb3+ energy transfer efficiency in a 70SiO2–30HfO2 glass and glass-ceramics waveguide in order to convert absorbed photons at 488 nm in photons at 980 nm. The evaluation of the transfer efficiency between Tb3+ and Yb3+ is obtained by comparing the luminescence decay of Tb with and without Yb co-doping ions. A transfer efficiency of 25 % obtained with glass-ceramic sample and 6 % with glass sample proving that glass-ceramic can be a viable system to fulfil our requirements. © Springer International Publishing Switzerland 2016.


Kappes M.S.,University of Vienna | Gruber K.,University of Vienna | Gruber K.,Johannes Kepler University | Frigerio S.,University of Vienna | And 5 more authors.
Geomorphology | Year: 2012

Many regions worldwide are threatened by multiple natural hazards with the potential to cause high damages and losses. However, the modeling of multiple hazards in a joint analysis scheme is still in the early stages of development as a range of serious challenges emerges in the multihazard context such as differing modeling approaches in use for contrasting hazards; the time- and data-demanding conduct of each single preparative, intermediate and analysis step; and the clear visualization of the modeling outcome. Under consideration of these difficulties, a regional multihazard exposure analysis concept is developed for five natural hazards: debris flows, rock falls, shallow landslides, avalanches, and river floods, complemented by a visualization scheme to present the modeling outcome. An automation of the two schemes resulted in a beta version of the MultiRISK modeling and the MultiRISK visualization software tool forming together the MultiRISK platform. To test the analysis scheme and the software implementation of MultiRISK a case study is performed in the Barcelonnette basin in France with a worst-case parameterization of the models on the basis of extensive literature reviews. Experiences from this case study offered many insights into the multihazard topic and even more questions, e.g. with respect to coherent multihazard model parameterization, validation or the comparability and interpretation of single-hazard modeling results, respectively. Although analysis schemes can be proposed and software tools can be provided to facilitate many steps, a well-conceived and reflective approach to multihazard settings is essential. The worst-case analysis based on literature values apparently leads to an overestimation of the susceptible areas and the number of exposed elements. Nevertheless, depending on the data situation of an area, especially in areas without any information on past events, this approach may offer the determination of general hazard distributions, overlaps, and areas of potential risk without data-demanding calibration. © 2012 Elsevier B.V.

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