Highly Subwavelength, Superdirective Cylindrical Nanoantenna

© 2018 American Physical Society. A superdirective cylindrical nanoantenna is demonstrated with a multilayered cylindrical metamaterial-inspired structure. Targeting specific scattering coefficients for the dipole and higher-order modes, the ideal limit of needle radiation is demonstrated. A five-layer system is optimized to demonstrate its approach to the theoretical directivity bound. While the resulting structure is scalable to any frequency regime, its highly subwavelength overall size (λ0/10) takes advantage of combinations of positive and negative permittivity materials in the optical regime

Nano-sensing of the orientation of fluorescing molecules with active coated nano-particles

© 2014 Elsevier B.V. All rights reserved. The potential of using active coated nano-particles to determine the orientation of fluorescing molecules is reported. By treating each fluorescing molecule as an electric Hertzian dipole, single and multiple fluorescing molecules emitting coherently and incoherently in various orientations are considered in the presence of active coated nano-particles. It is demonstrated that in addition to offering a means to determine the orientation of a single molecule or the over-all orientation of the molecules surrounding it, the nature of the far-field response from the active coated nano-particles provides insight into the degree of phase coherence between emitters in specific molecular environments

Directive properties of active coated nano-particles

© 2012, Advanced Electromagnetics. All rights reserved. The directivities of the fields radiated by a variety of cylindrical and spherical active coated nano-particles, which are excited by their respective sources of illumination at optical frequencies, are investigated. Particular attention is devoted to the influence of the source location and optical gain constant on the directivities. While significant variations in the directivities are realized in the cylindrical cases for different source locations within and slightly outside the nano-particles and values of the optical gain constant, the corresponding spherical cases exhibit negligible differences

Riemann-Hilbert technique scattering analysis of metamaterial-based asymmetric 2D open resonators

© P.M. Kamiński et al., published by EDP Sciences, 2017. The scattering properties of metamaterial-based asymmetric two-dimensional open resonators excited by an electric line source are investigated analytically. The resonators are, in general, composed of two infinite and concentric cylindrical layers covered with an infinitely thin, perfect conducting shell that has an infinite axial aperture. The line source is oriented parallel to the cylinder axis. An exact analytical solution of this problem is derived. It is based on the dual-series approach and its transformation to the equivalent Riemann-Hilbert problem. Asymmetric metamaterial-based configurations are found to lead simultaneously to large enhancements of the radiated power and to highly steerable Huygens-like directivity patterns; properties not attainable with the corresponding structurally symmetric resonators. The presented open resonator designs are thus interesting candidates for many scientific and engineering applications where enhanced directional near- and far-field responses, tailored with beam shaping and steering capabilities, are highly desired

Cylindrical and spherical active coated nanoparticles as nanoantennas

Researchers review the fundamental properties of several spherical and cylindrical, passive, and active coated nanoparticles (CNPs) with an emphasis on their potential for nanoantenna and nanoamplifier synthesis. For the spherical geometries, the nanoparticles are excited by an electric Hertzian dipole (EHD), which represents a stimulated atom or molecule. The cylindrical nanoparticles are excited by a magnetic line source (MLS). In the active cases, gain is added to the core region of the particle. For simplicity, it is represented by a canonical, frequency-independent gain model. They demonstrate that specific CNPs can be designed to be resonant and well matched to their respective excitation sources

Erratum: Highly Subwavelength, Superdirective Cylindrical Nanoantenna (Physical Review Letters (2018) 120 (237401): DOI: 10.1103/PhysRevLett.120.237401)

© 2018 2018 American Physical Society. A superdirective cylindrical nanoantenna is demonstrated with a multilayered cylindrical metamaterial-inspired structure. Targeting specific scattering coefficients for the dipole and higher-order modes, the ideal limit of needle radiation is demonstrated. A five-layer system is optimized to demonstrate its approach to the theoretical directivity bound. While the resulting structure is scalable to any frequency regime, its highly subwavelength overall size takes advantage of combinations of positive and negative permittivity materials in the optical regime

Factors that Determine Child Behavior during Dental Treatment

In this review paper we wanted to summarize all the aspects which could affect the behavior of the child patients in the dental office. At the beginning, the factors that are related to the child patients are mentioned. Various segments of child psychological, cognitive, physiological and other kinds of development are discussed. Also, the reasons for dental fear and anxiety (DFA) and dental behavior problems (DBP) were analyzed, and how the child dental patients could cope with them. Finally, types of patients according to their behavior in the dental office were discussed. Furthermore, the influences of child patients’ parents were studied, including parenting styles, as well as factors related to dentist, dental team and the dental office. Finally, critical evaluation of administration of assets to measure the presence of DFA and DBP is provided. Every part of the text was corroborated by the results from our own and other authors’ recent bibliography data