Salandrino, Alessandro
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Publication Shaping Light Beams in the Nanometer Scale: A Yagi-Uda Nanoantenna in the Optical Domain(2007-12-06) Salandrino, Alessandro; Li, Jingjing; Engheta, NaderAYagi-Uda-like optical nanoantenna concept using resonant core-shell plasmonic particles as its “reflectors” and “directors” is studied numerically. Such particles when placed near an optical dipole source in a certain arrangement may exhibit large induced dipole moments, resulting in shaping the far-field radiation pattern, analogous to the far field of classical Yagi-Uda antennas in the microwave regime. The variation of the ratio of radii in concentric core-shell nanostructure is used to tailor the phase of the polarizabilities of the particles and, consequently, the antenna’s far-field pattern. The idea of a nanospectrum analyzer is also briefly proposed for molecular spectroscopy.Publication Optical spectrometer at the nanoscale using optical Yagi-Uda nanoantennas(2009-05-05) Salandrino, Alessandro; Li, Jingjing; Engheta, NaderHere we present and analyze an optical spectrum analyzer at the nanometer scale that is able to distribute different frequency contents of the radiation of an optical dipole source into different directions in the space. The spectrum analyzer is composed of arrays of optical Yagi-Uda nanoantennas, forming relatively narrow radiation patterns operating at different frequencies. The optical Yagi-Uda nanoantennas composed of plasmonic core-shell nanoparticles are used as an example of building blocks for this idea in our study. Narrow radiation beams in such antenna arrays are realized by tailoring the scattering phase of the nanoparticles. The sensitivity of such an antenna array to the operating wavelength and the angular distribution of the radiation pattern, which is essential for the operation of the spectrum analyzer proposed here, is studied theoretically. The chromatic dispersion and the angular variation of the radiation pattern of such an optical spectrum analyzer are discussed in detail.Publication Circuit Elements at Optical Frequencies: Nanoinductors, Nanocapacitors, and Nanoresistors(2005-08-26) Engheta, Nader; Salandrino, Alessandro; Alù, AndreaWe present the concept of circuit nanoelements in the optical domain using plasmonic and nonplasmonic nanoparticles. Three basic circuit elements, i.e., nanoinductors, nanocapacitors, and nanoresistors, are discussed in terms of small nanostructures with different material properties. Coupled nanoscale circuits and parallel and series combinations are also envisioned, which may provide road maps for the synthesis of more complex circuits in the IR and visible bands. Ideas for the optical implementation of right-handed and left-handed nanotransmission lines are also forecasted.