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Signal processing in photonic crystals and nanostructures
2006
International audience; Optical devices employing photonic crystals and novel nanostructure materials may exhibit useful properties for applications to all-optical signal processing. In this work we analyze as a first example four-wave mixing of polarized beams in photonic crystal fibers. We show that by properly tuning the pump wavelength and the linear dispersion properties of the fiber one may obtain broadband parametric amplification and frequency conversion. Next we consider the in-line periodic amplification of short optical pulses by means of quantum-dot semiconductor optical amplifiers. We show by numerical simulations that pattern-free amplification of a 40 Gbit/s soliton signal at…
Atomic layer deposition of AlN from AlCl3 using NH3 and Ar/NH3 plasma
2018
The atomic layer deposition (ALD) of AlN from AlCl3 was investigated using a thermal process with NH3 and a plasma-enhanced (PE)ALD process with Ar/NH3 plasma. The growth was limited in the thermal process by the low reactivity of NH3, and impractically long pulses were required to reach saturation. Despite the plasma activation, the growth per cycle in the PEALD process was lower than that in the thermal process (0.4A ° vs 0.7A ° ). However, the plasma process resulted in a lower concentration of impurities in the films compared to the thermal process. Both the thermal and plasma processes yielded crystalline films; however, the degree of crystallinity was higher in the plasma process. The…
Refractive index sensing by a silicon metasurface
2022
The availability of smart materials represents a key enabling milestone for the realization of smart sensors. In this research field, optical sensing has gained a lot of attention in various applications ranging from basic physics to chemistry and biology. Here, we exploit the non-invasive nature of light to achieve an innovative sensor based on all-optical dielectric nano-resonators arranged in a periodic fashion. The proposed sensor can measure refractive index changes up to 10(-6).
Unravelling the Intertwined Atomic and Bulk Nature of Localised Excitons by Attosecond Spectroscopy
2021
The electro-optical properties of most semiconductors and insulators of technological interest are dominated by the presence of electron-hole quasi-particles, called excitons. The manipulation of excitons in dielectrics has recently received great attention, with possible applications in different fields including optoelectronics and photonics. Here, we apply attosecond transient reflection spectroscopy in a sequential two-foci geometry and observe sub-femtosecond dynamics of a core-level exciton in bulk MgF2 single crystals. Furthermore, we access absolute phase delays, which allow for an unambiguous comparison with theoretical calculations. Our results show that excitons surprisingly exhi…
New charge transfer salts of two organic π-donors of the tetrathiafulvalene type with the paramagnetic [Cr(NCS)6]3- anion
2003
cited By 9; International audience; The electrochemical combination of the paramagnetic anion [Cr(NCS)6]3- with the organic π-donors bis(ethylenedithio)tetrathiafulvalene (ET) and 4,5-bis(2-hydroxyethylthio) -4′,5′-ethylenedithiotetrathiafulvalene (DHET-EDTTTF) leads to two new radical cation salts, namely (ET)4 [Cr(NCS 6]·PhCN 1 and (DHET-EDTTTF)2 (NEt4)[Cr(NCS)6] 2. Both have been characterized by X-ray crystallography, magnetic and resistivity measurements. The structure of 1 consists of alternating inorganic layers generated by the anions and organic layers in which the PhCN molecules are inserted; the organic sub-lattice is built up from four different ET units, three of them with a ch…
Blue Emitting Organic Light Emitting Diodes
2019
Organic light emitting diodes (OLEDs) [1] can be fabricated on a range of materials such as glass, silicon or flexible plastic substrates. This can be exploited for the realization of integrated OLED-based fluorescence chemical sensors [2] and microfluidic systems [3] for application in areas such as biotechnology, life sciences, pharmaceuticals, public health and defense. These devices hold promises to be cost effective, ultra-compact (including the possibility to be fabricated into large bidimensional arrays), and capable to handle smaller sample volumes in order to achieve high throughput. Blue light is advantageous because it is strongly absorbed by most sensing molecules attached to bi…
The nature of the syllabic neighbourhood effect in French
2006
International audience; We investigated whether and how sublexical units such as phonological syllables mediate access to the lexicon in French visual word recognition. To do so, two lexical decision task (LDT) experiments examined the nature of the syllabic neighbourhood effect. In Experiments 1a and b, the number of higher frequency syllabic neighbours was manipulated while controlling for the first bigram. The results failed to show a pure syllabic neighbourhood effect. In Experiments 2a and b, syllabic neighbourhood and bigram frequency were factorially manipulated. The interaction showed that the syllabic neighbourhood effect was inhibitory when bigram frequency was high, whereas it wa…
Sfide postmoderne a una paideia umanistica
2016
In questo saggio sono esposte le tesi caratterizzanti del pensiero debole, inteso come Weltanschauung spontanea diffusa tra le nuove generazioni e interpretato come sfida radicale all’idea centrale di una paideia di tradizione umanistica. Sono poi presi in esame alcuni rilievi critici emersi dal cosiddetto “realismo critico”, relativi al misconoscimento della realtà e delle differenze. L’autore le discute e le approfondisce nella prospettiva di una ontologia della persona, essenzialmente definita dalle categorie di avvenimento formativo e di riconoscimento, della realtà, dei volti, delle differenze. In this essay are exposed the main thesis of the weak thought, meant as spontaneous Weltansc…
La Madonna della Bruna di Monreale: un testimone della 'maniera cypria' nell’abbazia benedettina del re Guglielmo II
2019
Il saggio affronta lo studio storico-artistico di un antico dipinto su tavola della Cattedrale di Monreale rappresentante la Madonna col Bambino nell'iconografia dell'Odigitria. Tradizionalmente datato al XII o addirittura all'XI secolo e collegato al re Guglielmo II "il buono", grazie ai risultati del recente restauro scientifico si è invece spostata la datazione alla metà del XIII secolo, come prodotto della cosiddetta 'maniera cypria' diffusa in Italia meridionale e nell'area mediterranea, dovuto piuttosto alla committenza di un abate-arcivescovo di Monreale. The essay deals with the historical-artistic study of an ancient painting on wood of the Cathedral of Monreale representing the Ma…
L’ODIGITRIA DETTA ‘DI GUGLIELMO II’ DELLA CATTEDRALE DI MONREALE
2019
Il volume affronta lo studio storico-artistico e tecnico-scientifico di un antico dipinto su tavola della Cattedrale di Monreale rappresentante la Madonna col Bambino nell'iconografia dell'Odigitria. Tradizionalmente datato al XII o addirittura all'XI secolo e collegato al re Guglielmo II "il buono", grazie ai risultati del recente restauro scientifico si è invece spostata la datazione alla metà del XIII secolo, come prodotto della cosiddetta 'maniera cypria' diffusa in Italia meridionale e nell'area mediterranea, dovuto piuttosto alla committenza di un abate-arcivescovo di Monreale. The book deals with the historical-artistic and technical-scientific study of an ancient painting on wood of…