1,721,576 research outputs found
Gianluca Chiadini, Alain Nadaud. L’écrivain philosophe
No full textProfessore di storia dell’arte nella scuola secondaria di secondo grado e già autore del saggio Il romanzo archeologico in Francia. Il caso di “Auguste fulminant” di Alain Nadaud (Roma, Aracne editrice, 2019), Gianluca Chiadini prosegue la sua ricerca sull’écrivain philosophe francese con questa seconda e curata pubblicazione, dove si intersecano molteplici e complementari percorsi di studio e di riflessione sulla vita, il pensiero e la scrittura di uno dei maestri del romanzo archeologico co..
Gaussian model for refractive indexes of columnar thin films and Bragg multilayers [Opt. Commun. 231 (1-6) (2004) 257-261] DOI:10.1016/j.optcom.2003.12.030
No full textExtension of Hodgkinson's model for optical characterization of columnar thin films
No full textAn extension of Hodgkinson's model for the principal refractive indexes and column-inclination angle of a columnar thin film against the vapor-incidence angle is presented for an extraordinary refractive index relevant,for many optical applications. Not only do the principal refractive indexes depend quadratically on the vapor incidence angle, but the extraordinary refractive index does as well. This model is expected to be valid for chiral sculptured thin films as well
Gaussian model for refractive indexes of columnar thin films and Bragg multilayers
No full textWe characterize both the ordinary and extraordinary refractive indexes of columnar thin films (CTFs) as Gaussian functions of the vapor incidence angle. This simple model is compared to the one available in literature for three different materials, resulting in low relative errors. The Gaussian model can be easily used to design Bragg multilayers made of CTFs
Bicontrollable terahertz metasurface with subwavelength scattering elements of two different materials
No full textTransmission of a normally incident plane wave through a metasurface with bicontrollable subwavelength scattering elements was simulated using a commercial software. Some pixels composing the
-shaped scattering elements were made of a magnetostatically controllable material whereas the remaining pixels were made of a thermally controllable material, the metasurface designed to operate in the terahertz spectral regime. The copolarized transmission coefficients were found to exhibit stopbands that shift when either a magnetostatic field is applied or the temperature is increased or both. Depending on spectral location of the stopband, either the magnetostatic field gives coarse control and temperature gives fine control or vice versa. The level of magnetostatic control depends on the magnetostatic-field configuration
Design of wideband circular-polarization filters made of chiral sculptured thin films
No full textCascades of chiral sculptured thin films (STFs) with successive pitches forming a geometric series are theoretically shown to junction as wideband circular-polarization filters. A simple design paradigm is provided
Optimal Design of Coatings for Mirrors of Gravitational Wave Detectors: Analytic <i>Turbo</i> Solution via Herpin Equivalent Layers
No full textIn this paper, an analytical solution to the problem of optimal dielectric coating design of mirrors for gravitational wave detectors is found. The technique used to solve this problem is based on Herpin’s equivalent layers, which provide a simple, constructive, and analytical solution. The performance of the Herpin-type design exceeds that of the periodic design and is almost equal to the performance of the numerical, non-constructive optimized design obtained by brute force. Note that the existence of explicit analytic constructive solutions of a constrained optimization problem is not guaranteed in general, when such a solution is found, we speak of turbo optimal solutions
Transmission properties of perturbed optical cantor multilayer
No full textFractal multilayers of two distinct dielectric materials are structures exhibiting stop bands and transmission peaks in their electromagnetic response. In this work we analyze how the transmission spectrum of a Cantor fractal multilayer changes when a defect, consisting of a dielectric layer different from those constituting the multilayer, is inserted midway through its thickness. Unlike a periodic multilayer structure, no transmission peaks (defect modes) appear in the stop band by inserting a defect in a Cantor multilayer. We show that a defect in the fractal structure results in a frequency shift of its transmission spectrum and in a change of the width of both stop bands and transmission peaks. The extent of such spectrum modifications depends on either the thickness and the refractive index of the defect layer. By suitably modulating these parameters a tunable narrow band filter can be realized to cover a desired range of frequency. This feature may hold attraction for certain applications such as dense wavelength division multiplexing systems and sensors
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