1,720,977 research outputs found
Multilayer optical routing by means of vertical directional coupler with long range surface plasmons
No full textSubwavelength coherent control and coupling of light in plasmonic nanoresonators on dielectric waveguides
No full textWe report results on the possibility of subwavelength coherent control of light in coupled plasmonic nanoresonators on dielectric waveguides. Our calculations show that subwavelength regions of the plasmonic structure, spatially separated by a few nanometers, can be individually addressed by controlling the relative phase of the injected fields. We also show the complementary possibility to efficiently inject a guided mode into a planar dielectric waveguide by collecting the radiation emitted by wire-like and/or point-like sources, placed into the resonators. For example, this configuration provides a useful and powerful tool to control the emission of the localized sources such as stripes of fluorescent molecules or quantum dots placed in the gaps between the plasmonic structures. Possible applications of the considered study include plasmonic logic gates, integrated sensors for single-molecule fluorescence, and ready-to-use devices based on plasmonic single-photon sources. © 2013 Optical Society of America
Engineering the second harmonic generation pattern from coupled gold nanowires
No full textWe numerically investigated second harmonic generation from systems composed of two coupled gold nanowires. The developed method allows one to arbitrarily change the shape of the wire cross section in order to explore the generated and scattered field patterns. Our results suggest that the overall second harmonic generation is related to the electromagnetic energy per unit length stored in the gap area between the wires. These geometrical considerations make further optimization possible. As an example we discuss the possibility to select dipolar emission and/or quadrupolar emission patterns. The selection mechanism responsible for this kind of emission can be traced back to the interaction between nonlinear sources with the surface plasmon resonance of the metallic wires. (C) 2010 Optical Society of Americ
Numerical evaluation of irradiation diagram by plasmonic gratings and slit apertures
No full textWe describe a fast method to evaluate the far-field profile of a generic planar disposition of plasmonic gratings and
slit apertures, based on the ideal decomposition of the structure into a linear array of distinct scattering elements
and provided an accurate description of their plasmonic and radiating behaviors. This approach allows for a fast
calculation of the irradiation diagram, and has general validity for any kind of surface defects and for multiple set
of gratings and slit apertures
Second harmonic circular dichroism by self-assembled metasurfaces [Invited]
No full textIt is possible to obtain an optical response from metasurfaces that exhibit second- order circular dichroism thanks to the recent successes in nanotechnology, opening the way to new functionalities on a spatial scale of few hundred on nms. The second order nonlinear response of this kind of nanostructured materials is an interesting and fascinating issue. The second-order nonlinear response of this kind of nanostructured materials is an interesting, as becomes clear from an overview of second harmonic generation and in particular the nonlinear circular dichroism raised by metasurfaces of different morphologies and material components, realized by means of self-assembling methods. In this review we show as the Second Harmonic Generation Circular Dichroism is very sensitive and useful in the field of nanotechnology characterization
Analysis on vertical directional couplers with long range surface plasmons for multilayer optical routing
No full text
Second harmonic generation from 3D nanoantennas: on the surface and bulk contributions by far-field pattern analysis
No full textWe numerically study second harmonic generation from dipole gold nanoantennas by analyzing the different contributions of bulk and surface nonlinear terms. We focus our attention to the properties of the emitted field related to the different functional expressions of the two terms. The second harmonic field exhibits different far and near field patterns if both nonlinear contributions are taken into account or if only one of them is considered. This effect persists despite of the model used to estimate the parameters of the nonlinear sources and it is strictly related to the resonant behavior of the plasmonic nanostructure at the fundamental frequency field and to its linear properties at the second harmonic frequency. We show that the excitation of localized surface plasmon polaritons in these structures can remarkably modify the nonlinear response of the system by enhancing surface and/or bulk contributions, creating regimes where bulk nonlinear terms dominate over surface linear terms and vice versa. Finally, the results of our calculations suggest a method that could be implemented to experimentally extract information on the relevance of bulk and surface contributions by measuring and analyzing the generated far field second harmonic patterns in metal nanoantennas and, more in general, in plasmonic nanostructures
Coupled 2D Ag nano-resonator chains for enhanced and spatially tailored second harmonic generation
No full textWe report results of second harmonic generation calculations performed on Silver coupled 2D-nanoresonators. Coupling is responsible for the creation of resonant modes that can be localized on small portions of the structure or distributed over the whole structure. Different field profiles can be obtained by varying the parameters of the input field (i.e. the wavelength). The second harmonic generation nonlinear process is enhanced by the excitation of coupled surface plasmon polaritons. The emitted field is strongly affected by the linear properties of the structure behaving as a nano antenna. We note that different configurations of the pump field lead to different second harmonic far-field emission patterns. Also, we show that the angular emission of the second harmonic field contains information about the spatial location of the pump field hot spots at different frequencies. Applications to a new class of nano sources for single molecule fluorescence and sensors are proposed
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