2021, Editoriale in rivista, ENG
Courtial, Johannes; Fischer, David; Larina, Irina V.; Marino, Antigone; Mphuthi, Nokwazi; Rody, Sarah G.; Carney, P. Scott
2012, Articolo in rivista, ENG
Herrera I. [ 1 ] ; Petrovic J. [ 1,2 ] ; Lombardi P. [ 1,3 ] ; Consolino L. [ 1,4 ] ; Bartallini S. [ 1 ] ; Cataliotti F.S. [ 1,5 ]
The integration of cold atomic sources and electromagnetic field sources in the same device is a major frontier for both fundamental science and advanced technology. In this paper, we discuss the realization of the Bose-Einstein condensate (BEC) on an AtomChip and describe such an experimental configuration realized at LENS. We also concentrate on the realization of a particular integrated matter wave interferometer where coherent coupling between the BECs in different Zeeman states is used to produce a fringe time-population signal at the output. Finally, we discuss the prospects for application of such a device as a multi-path interferometer.
2009, Articolo in rivista, ENG
Michele Suman; Gianni Monaco; Maria Guglielmina Pelizzo; David L. Windt; Piergiorgio Nicolosi;
The experimental characterization of an aperiodic reflecting multilayer (ML) structure designed to reflect and compress attosecond pulses in the extreme ultraviolet spectral region is presented. The MLs are designed for the 75-105 eV spectral interval with suitable reflectance and phase behavior, in particular high total spectral reflectivity coupled with very wide bandwidth and spectral phase compensation. The experimental phase behavior of the multilayer has been obtained through electron photoemission signal using an innovative method that is presented and discussed in this paper. With this ML we have demonstrated pulse compression by reflection from 450 as to 130 as. (C) 2009 Optical Society of America
2008, Articolo in rivista, ENG
Poletto, L; Villoresi, P; Benedetti, E; Ferrari, F; Stagira, S; Sansone, G; Nisoli, M
Ultrafast extreme-ultraviolet pulses are spectrally selected by a time-delay-compensated grating monochromator. The intrinsic very short duration of the pulses is obtained by exploiting the high-order harmonic generation process. The temporal characterization of the harmonic pulses is obtained using a cross-correlation method: pulses as short as 8 fs are measured at the output of the monochromator in the case of the 23rd harmonic. This value is in agreement with the expected duration of such pulses, indicating that the influence of the monochromator is negligible. The photon flux has been measured with a calibrated photodiode, pointing out the good efficiency of the monachromator, derived by the exploitation for the two gratings of the conical diffraction mounting.
2008, Articolo in rivista
Bernini R, De Nuccio E, Minardo A, Zeni L, Sarro PM
The fabrication and characterization of a liquid-core/liquid-cladding integrated antiresonant reflecting optical waveguide (L-2-ARROW) is presented. In this waveguide, the light is confined vertically by the ARROW mechanism, whereas the lateral confinement is obtained by using liquid-core/liquid-cladding (L-2 waveguides) with different refractive indexes. This approach permits to realize L-2 waveguides with very low refractive index core (n approximate to 1.333) and represents a new solution to solve the difficulty to reduce the optical losses in 2D-ARROWs due to the TM polarization in lateral direction. The device has been fabricated with standard silicon technology. The results show that the optical properties can be tuned by changing the type and the flow velocity of the core and the cladding liquids.
2006, Articolo in rivista, ENG
Nanni M.; Pedreschi D.
Spatio-temporal, geo-referenced datasets are growing rapidly, and will be more in the near future, due to both technological and social/commercial reasons. From the data mining viewpoint, spatio-temporal trajectory data introduce new dimensions and, correspondingly, novel issues in performing the analysis tasks. In this paper, we consider the clustering problem applied to the trajectory data domain. In particular, we propose an adaptation of a density-based clustering algorithm to trajectory data based on a simple notion of distance between trajectories. Then, a set of experiments on synthesized data is performed in order to test the algorithm and to compare it with other standard clustering approaches. Finally, a new approach to the trajectory clustering problem, called temporal focussing, is sketched, having the aim of exploiting the intrinsic semantics of the temporal dimension to improve the quality of trajectory clustering.
2006, Articolo in rivista
Jedrkiewicz, O; Brambilla, E; Bache, M; Gatti, A; Lugiato, LA; Di Trapani, P
We consider travelling-wave parametric down-conversion in the high-gain regime and present the experimental demonstration of the quantum character of the spatial fluctuations in the system. In addition to showing the presence of sub-shot noise fluctuations in the intensity difference, we demonstrate that the peak value of the normalized spatial correlations between signal and idler lies well above the line marking the boundary between the classical and the quantum domain. This effect is equivalent to the apparent violation of the Cauchy-Schwartz inequality, predicted by some of us years ago, which represents a spatial analogue of photon antibunching in time. Finally, we analyse numerically the transition from the quantum to the classical regime when the gain is increased and we emphasize the role of the inaccuracy in the determination of the symmetry centre of the signal-idler pattern in the far-field plane.
2006, Articolo in rivista, ENG
Bukreeva, I; Surpi, A; Gerardino, A; Lagomarsino, S; Perennes, F; Altissimo, M; Cabrini, S; Carpentiero, A; Vicenzo, A; Cavallotti, P
A novel route for fabrication of compact optical system for X-rays is presented. It is based on the extensive use of tools developed for microelectronics and micromechanics: electron beam lithography, optical lithography and X-ray lithography. Virtually any shape can be obtained in order to match the system to the different needs. In this paper, we concentrate the attention on focusing system made by nested mirrors. A system for synchrotron radiation source and one for laboratory source have been designed and simulated by a ray-tracing code developed ad hoc. The main parameters and the fabrication tolerance errors have been evaluated. The first prototypes have been produced following different fabrication routes. They are presented here together with considerations for future developments. (c) 2005 Elsevier B.V. All rights reserved.
2004, Contributo in atti di convegno, ENG
Bonora, S; Pascolini, M; Poletto, L; Sansone, G; Stagira, S; Vozzi, C; Nisoli, M; Villoresi, P; Tondello, G; De Silvestri, S
In this work we report on the optimization of the conversion efficiency of the harmonic generation process, by adaptive control of the wavefront of sub-10-fs light pulses, obtained by using a deformable mirror and a genetic algorithm. Sub-10-fs, 0.2-mJ energy light pulses, generated by the hollow-fiber compression technique, were focused in the gas target (argon or neon) by a 250-mm focal-length mirror. Pulse wavefront correction has been achieved by using a deformable mirror (DM) controlled by 37 actuators distributed on a honeycomb pattern of 15 mm diameter. The harmonic radiation was observed by a soft-X-ray spectrometer, with double output: time-integrated high-resolution bidimensional focal-plane image and real-time (I kHz) intensity of a suitable spectral region. This latter signal was used as fitness parameter for the genetic algorithm; an initial population of DM configurations was initialized with random values of the actuator signals. A new generation of DM configurations is derived from ordering, selection and transformation of previous generation, up to the convergence to the fittest individual.
2001, Articolo in rivista, ENG
Sergio De Nicola; Pietro Ferraro; Andrea Finizio; Giovanni Pierattini
We present a concept of interferometric testing, believed to be novel, that can be applied to measuring aberrations of optical components that have rotational symmetry. The optical configuration uses two coherent, collimated wave fronts that are tilted to impinge upon the optical component being tested such that one beam is on axis and the other is off axis. For small tilt angles the two aberrated wave fronts can be considered to be carrying the same aberrations. Furthermore, the off-axis beam is displaced along a direction orthogonal to the optical axis of the component. Interference between the two aberrated wave fronts produces a fringe pattern that is similar to a lateral shear interference pattern. Moiré fringes are obtained by spatial beating of the interference pattern with a CCD TV camera array. Under such conditions it is possible to subtract most of the linear carrier that is intrinsically present in the resultant fringe pattern owing to the large defocus aberration and tilt.
2001, Articolo in rivista, ENG
S. De Nicola, P. Ferraro, A. Finizio and G. Pierattini
It is demonstrated for the first time to the authors' knowledge that digital holographic image reconstruction can be applied to correction of image reconstruction in the presence of severe anamorphism and aberrations. It is shown that anamorphism and aberrations can be taken into account and compensated for separately to yield a correct-image reconstruction. Anamorphism and aberrations are introduced by a holographic recording system based on a reflective grating interferometer (RGI). The strong anamorphic behavior of the RGI prevents reconstruction of a correct image unless that behavior is compensated for in the process of numerical holographic reconstruction.
1994, Articolo in rivista, ENG
E Nichelatti, A Tirabassi and E Melissano
Fabrication of a coated graded reflectance mirror (GRM) is based on a multilayer design where one or more layers have a radially variable thickness. We describe and experimentally validate a method that can be used to predict the shape of a profiled layer deposited by masking techniques. Deposition by masking techniques is modelled in the framework of the linear system theory. We also suggest an experimental procedure for estimating the Green function that rules particle gas diffusion, and we apply it to the case of RF-sputtering deposition of ZnSe monolayers on BK7 glass. Comparison of predicted and measured reflectivity profiles at lambda =1.064 mu m confirms the model validity.