1,729,582 research outputs found
Reflexiones de un...
No full textRelato de José Luis Vázquez-Poletti para la revista Sci-FdI.Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEpu
Hollow core fiber with an octave spanning bandgap
Full text linkWe thoroughly compare the out-of-plane bandgaps generated by three realistic two-dimensional lattices: a triangular and a square arrangement of holes and a triangular arrangement of rods. We demonstrate that, for any given hole diameter-to-pitch ratio d/Λ, the triangular arrangement of interconnected resonators generates the widest possible bandgap along the air line, and we propose a physical interpretation explaining these results. The design of a hollow core photonic bandgap fiber based on such a lattice and able to transmit light with sub-decibel-per-meter losses over an octave of frequencies is presented for the first time, to the best of our knowledge
Cuando la Ciencia Ficción toma las aulas
No full textArtículo de José Luis Vázquez-Poletti para la revista Sci-FdI.Depto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEpu
andrea-poletti-unibo/1q-13_paper: 1q&13_analysis
No full text<p>paper version: Nature Communications</p>
El Universo de Metro 2033 necesita tu contribución
No full textJosé Luis Vázquez-Poletti porque el universo imaginado por Dmitry Glukhovsky no debe limitarse al metro de Moscú ni ser obra de un solo escritorDepto. de Arquitectura de Computadores y AutomáticaFac. de InformáticaTRUEpu
L'adozione internazionale
No full textL’ADOZIONE INTERNAZIONALE
di BRUNILDE POLETTI DI TEODORO
701 1. Profili evolutivi
707 2. Convenzione de L’Aja del 29 maggio 1993
713 3. Ratifica della Convenzione de L’Aja e legge 31 dicembre 1998, n. 476
718 4. La disciplina dell’adozione internazionale. Gli organismi competenti
721 5. La Commissione per le adozioni internazionali
727 6. Gli enti autorizzati
735 7. Inizio del procedimento: la dichiarazione di disponibilità e la dichiarazione
di idoneità
745 8. La fase all’estero e l’ingresso del minore in Italia
753 9. Il controllo del provvedimento straniero da parte del giudice
763 10. L’espatrio di minori a scopo di adozione
Multimode nonlinear fibre optics: theory and applications
Full text linkOptical fibres have been developed as an ideal medium for the delivery of optical pulses ever since their inception (Kao & Hockham, 1966). Much of that development has been focused on the transmission of low-energy pulses for communication purposes and thus fibres have been optimised for singlemode guidance with minimum propagation losses only limited by the intrinsic material absorption of silica glass of about 0.2dB/km in the near infrared part of the spectrum (Miya et al., 1979). The corresponding increase in accessible transmission length simultaneously started the interest in nonlinear fibre optics, for example with early work on the stimulated Raman effect (Stolen et al., 1972) and on optical solitons (Hasegawa & Tappert, 1973). Since the advent of fibre amplifiers (Mears et al., 1987), available fibre-coupled laser powers have been increasing dramatically and, in particular, fibre lasers now exceed kW levels in continuous wave (cw) operation (Jeong et al., 2004) and MW peak powers for pulses (Galvanauskas et al., 2007) in all-fibre systems. These developments are pushing the limits of current fibre technology, demanding fibres with larger mode areas and higher damage threshold. However, it is increasingly difficult to meet these requirements with fibres supporting one single optical mode and therefore often multiple modes are guided. Non-fibre-based laser systems are capable of delivering even larger peak powers, for example commercial Ti:sapphire fs lasers now reach the GW regime. Such extreme powers cannot be transmitted in conventional glass fibres at all without destroying them (Gaeta, 2000), but there is a range of applications for such pulses coupled into hollow-core capillaries, such as pulse compression (Sartania et al., 1997) and high-harmonic generation (Rundquist et al., 1998). For typical experimental parameters, these capillaries act as optical waveguides for a large number of spatial modes and modal interactions contribute significantly to the system dynamics.In order to design ever more efficient fibre lasers, to optimise pulse delivery and to control nonlinear applications in the high power regime, a thorough understanding of pulse propagation and nonlinear interactions in multimode fibres and waveguides is required. The conventional tools for modelling and investigating such systems are based on beam propagation methods (Okamoto, 2006). However, these are numerically expensive and provide little insight into the dependence of fundamental nonlinear processes on specific fibre properties, e.g., on transverse mode functions, dispersion and nonlinear mode coupling. For such an interpretation a multimode equivalent of the nonlinear Schrodinger equation, the standard and highly accurate method for describing singlemode nonlinear pulse propagation (Agrawal, 2001; Blow & Wood, 1989), is desirable. In this chapter, we discuss the basics of such a multimode generalised nonlinear Schrodinger equation (Poletti & Horak, 2008), its simplification to experimentally relevant situations and a few select applications. We start by introducing and discussing the theoretical framework for fibres with χ(3) nonlinearity in Sec. 2. The following sections are devoted to multimode nonlinear applications, presented in the order of increasing laser peak powers. A sample application in the multi-kW regime is supercontinuum generation, discussed in Sec. 3. Here we demonstrate how fibre mode symmetries and launching conditions affect intermodal power transfer and spectral broadening. For peak powers in the MW regime, self-focusing effects become significant and lead to strong mode coupling. The spatio-temporal evolution of pulses in this limit is the topic of Sec. 4. Finally, at GW peak power levels, optical pulses can only be delivered by propagation in gases. Still, intensities become so high that nonlinear effects related to ionisation must be taken into account. An extension of the multimode theory to include these extreme high power effects is presented in Sec. 5 and the significance of mode interaction is demonstrated by numerical examples pertaining to a recent experiment. Finally, we end this chapter with conclusions in Sec. 6
«Syria Poletti y su lengua en Gente conmigo»
No full textIl contributo analizza gli aspetti morfosintattici e lessicali più rilevanti dello spagnolo del primo romanzo dell’autrice italo-argentina Syria Poletti, Gente conmigo, riscontrando una grande padronanza della lingua e dimostrando di aver assimilato in tal modo la lingua degli argentini che riesce a riflettere anche l’aspetto colloquiale. Sono state anche esaminate alcune risorse stilistiche adoperate dall’autrice
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