Cylindrical and Spherical Active Coated Nanoparticles as Nanoantennas: Active Nanoparticles as Nanoantennas

Abstract

In this work we review the fundamental properties of several spherical and cylindrical, passive and active, coated nano-particles (CNPs) with emphasis on their potential for nanoantenna and nano-amplifier synthesis. For the spherical geometries, the nano-particles are excited by an electric Hertzian dipole, which represents, e.g., a stimulated atom or molecule. The cylindrical nano-particles are excited by a magnetic line source. In the active cases, gain is added to the core region of the particle. For simplicity, it is modelled by a canonical, frequency independent gain model. We demonstrate that specific CNPs can be designed to be resonant and well-matched to their respective excitation sources. With active cores, these designs can lead to extremely large total radiated powers. For both configurations, insights into the effects of the nano-particle material composition, source location and orientation will be given on the basis of studying their near-field and power flow density distributions, their total radiated powers, and their directivity properties.

Active coated nano rod antennas for enhanced and directive scattering phenomena

“…Before we proceed with the results pertaining to a variety of CNRs, following remarks are in order. First, when the length of the cylindrical core-shell part of the symmetric CNR is h =∞, see Figure 1a, then the symmetric CNR goes over to a 2D cylindrical coated nano particle (CNP) investigated analytically in [26]. On the other hand, when h = 0, the symmetric CNR recovers a 3D spherical CNP studied by analytical means in [24,26].…”

“…Such a small nanometer thickness requires, however, very accurate sizedependent permittivity models of the plasmonic nanoshells. Appropriate permittivity models have been developed and used successfully for a range of nano-shell thicknesses; the specific behavior of the permittivity pertaining to a 6 nm thick Ag nano-shell used in this work can be found in e.g., [24,26]. Over the visible range of wavelengths, 450-700 nm, which is sufficient for the illustration of all results for the light-CNR interactions examined presently, the real part of the Ag permittivity is negative while its imaginary part implies a rather lossy behavior.…”

“…However, the full potential and performance of plasmonic-based NAs is to some extent hindered by the large plasmonic losses at optical frequencies. To circumvent the loss issue, the use of gain materials was proposed in a variety of active plasmonic particles [24][25][26] for which significantly enhanced radiation and scattering characteristics were reported.…”

Subwavelength plasmonic nanoantenna as a Plasmonic Induced Polarization Rotator (PI-PR)

“…The spherical active CNP and dielectric SiO 2 constructs the proposed PI-PR models. The detail study of these material models can be found in [27][28][29][30][31] . The PI-PR models are simulated by a computational electromagnetic simulation set of tools utilizing CST Microwave Studio, which solves Maxwell's equations using frequency domain method.…”

Can a dielectric sphere emulate the behavior of a surface impedance sphereƒ

“…Undoubtedly, electromagnetic scattering by a sphere is an archetypical testbed for physics [1], and exotic engineering conceptualization [2]. In this work, we attempt the merge between two characteristic scattering problems, i.e., scattering by a penetrable dielectric sphere and by a impenetrable surface impedance sphere.…”