1,721,023 research outputs found
Angle and Polarization Tunability of Third-Order Nonlinear Optical Properties in Hyperbolic Multilayer Metamaterials
No full textOne of the greatest requirements of nanophotonics are metamaterials with properly engineered linear and nonlinear optical response by structure design and able to actively manipulate light at the nanoscale. In this work, hyperbolic multilayers with different metal filling fractions are fabricated and their third-order optical nonlinearities are investigated at different angles with TE- and TM-polarized light. A continuous modulation of the nonlinear absorption coefficient and the nonlinear refractive index is revealed as a function of the light incidence angle. A model is proposed to predict the angle- and polarization-dependent nonlinear parameters taking into account the optical anisotropy and the local intensity enhancement within the metamaterials
A solid-state route for the synthesis of metal nanocluster composite glasses
No full textA field-assisted solid state ion exchange (FASSIE) approach is used to dope silicate glasses with mono- and/or multivalent ions, in which the diffusion of ions coming from a film deposited onto the glass surface is driven by an external electric field. Metal precipitation to form nanoparticles may take place during the ion exchange, depending on the process parameters, or it can be induced by irradiation with high power laser beams. Characterization of silicate glass samples doped with either gold or silver is performed by optical absorption and transmission electron microscopy
Tuning the linear and nonlinear optical properties of ordered plasmonic nanoarrays by morphological control with thermal annealing
No full textThe capability to tune the linear and nonlinear optical response of plasmonic nanoarrays is of great interest for the realization of solid-state plasmonic nanodevices with application in many different fields in nanophotonics.
In the present work we demonstrated the possibility to tailor, in a controlled way, the morphological properties of gold nanoprism arrays fabricated by nanosphere lithography, by performing thermal annealing treatments in
air, preserving their bidimensional ordered arrangement. This allows to engineer the linear optical properties of the samples, finely tuning the spectral position and amplitude of their surface plasmon resonance peak.
Moreover, we demonstrated that the fine control of the nanostructures' morphology provides a way to get the continuous modulation of the nonlinear optical parameters (nonlinear refractive index and nonlinear absorption
coefficient) of the nanoarray. The experimental findings have been supported by finite elements method electrodynamic simulations, which provided a very good agreement
Tunable optical nonlinearities in epsilon-near-zero Au/Al2O3 multilayer metamaterials
No full textWe demonstrate the angle, polarization and intensity tunability of the optical Kerr effect in gold/alumina metamaterials investigated by the z-scan technique. We propose a model to predict their effective nonlinear refractive index and absorption coefficient
Correlation among structural, electrical, and deep-level properties of Fe centers implanted in InP
No full textThe Fe-related properties in high-temperature Fe implanted and annealed InP were studied by means of PIXE-RBS-channeling and correlated with the results of electrical (current-voltage) measurements. It is found that the point defect mobility, the concentration of substitutional Fe, and the resistivity of the implanted layer, all follow a similar temperature behavior. For annealing temperatures higher than 500°C semi-insulating behavior controlled by the Fe2+ deep levels is observed. © 2003 Elsevier B.V. All rights reserved
High Fe solubility in InP by high temperature ion implantation
No full textHigh temperature (>200°C) Fe implantation in InP has been proved to be a suitable method to obtain high substitutional Fe concentrations ([Fe2+]>1018 cm-3), without substantial defect generation and Fe precipitation. Electrical (current-voltage), deep level (photo-induced current transient spectroscopy) and optical (photoluminescence) measurements have been used to assess the behaviour of the activated Fe fraction, which is compared with the total Fe concentration evaluated by secondary ion mass spectrometry. Our results show no detrimental effects on the electrical (and optical) Fe related properties for Fe peak concentrations as high as 2 × 1019 cm-3, in spite of a large inactive Fe fraction. A strong correlation between Fe activation and background n-doping concentration has been put in evidence. © 2001 Elsevier Science B.V
Design of optical Kerr effect in multilayer hyperbolic metamaterials
Full text linkThe design of optical materials in nonlinear devices represents a fundamental step for their optimization and miniaturization, that would significantly contribute to the progress of advanced nanophotonics and quantum technologies. In this work, the effect of geometry and composition of multilayer hyperbolic metamaterials on their third-order nonlinear optical properties, i.e. the optical Kerr effect, is investigated. One figure of merit is provided to be used as a predictive tool to design and best exploit the local intensity enhancement in low-loss metamaterials to be used for various applications in nonlinear nanophotonics
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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