Nonradiating anapole modes in dielectric nanoparticles

Nonradiating current configurations attract attention of physicists for many years as possible models of stable atoms. One intriguing example of such a nonradiating source is known as 'anapole'. An anapole mode can be viewed as a composition of electric and toroidal dipole moments, resulting in destructive interference of the radiation fields due to similarity of their far-field scattering patterns. Here we demonstrate experimentally that dielectric nanoparticles can exhibit a radiationless anapole mode in visible. We achieve the spectral overlap of the toroidal and electric dipole modes through a geometry tuning, and observe a highly pronounced dip in the far-field scattering accompanied by the specific near-field distribution associated with the anapole mode. The anapole physics provides a unique playground for the study of electromagnetic properties of nontrivial excitations of complex fields, reciprocity violation and Aharonov-Bohm like phenomena at optical frequencies.The work of A.E.M. was supported by the Australian Research Council via Future Fellowship program (FT110100037). The authors at DSI were supported by DSI core funds. Fabrication, Scanning Electron Microscope Imaging and NSOM works were carried out in facilities provided by SnFPC@DSI (SERC Grant 092 160 0139). Zhen Ying Pan (DSI) is acknowledged for SEM imaging. Yi Zhou (DSI) is acknowledged for silicon film growth. Leonard Gonzaga (DSI), Yeow Teck Toh (DSI) and Doris Ng (DSI) are acknowledged for development of the silicon nanofabrication procedure. B.N.C. acknowledges support from the Government of Russian Federation, Megagrant No. 14.B25.31.0019

All-Dielectric Optical Nanoantennas

We propose a new type of highly efficient Yagi-Uda nanoantenna and introduced a novel concept of superdirective nanoantennas based on silicon nanoparticles. In addition to the electric response, this silicon nanoantennas exhibit very strong magnetic resonances at the nanoscale. Both types of nanoantennas are studied analytically, numerically and experimentally. For superdirective nanoantennas we also predict the effect of the beam steering at the nanoscale characterized by a subwavelength sensitivity of the beam radiation direction to the source position

Topological effects in anisotropy-induced nano-fano resonance of a cylinder

We demonstrate that optical Fano resonance can be induced by the anisotropy of a cylinder rather than frequency selection under the resonant condition. A tiny perturbation in anisotropy can result in a giant switch in the principal optic axis near plasmon resonance. Such anisotropy-induced Fano resonance shows fast reversion between forward and backward scattering at the lowest-energy interference. The near and far fields of the particle change dramatically around Fano resonance. The topology of optical singular points and the trajectory of energy flux distinctly reveal the interaction between the incident wave and the localized surface plasmons, which also determine the far-field scattering pattern. The anisotropy-induced Fano resonance and its high sensitivity open new perspectives on light–matter interactions and promise potential applications in biological sensors, optical switches, and optomechanics

Traditional and emerging materials for optical metasurfaces

One of the most promising and vibrant research areas in nanotechnology has been the field of metasurfaces. These are two dimensional representations of metaatoms, or artificial interfaces designed to possess specialized electromagnetic properties which do not occur in nature, for specific applications. In this article, we present a brief review of metasurfaces from a materials perspective, and examine how the choice of different materials impact functionalities ranging from operating bandwidth to efficiencies. We place particular emphasis on emerging and non-traditional materials for metasurfaces such as high index dielectrics, topological insulators and digital metamaterials, and the potentially transformative role they could play in shaping further advances in the field

Dielectric nanoresonators and metamaterials

3 pags.descripción no proporcionada por scopusR.P.-D. acknowledges the financial support from the A*STAR SERC Pharos program (Grant No. 152 73 00025, Singapore) and AME Programmatic Grant No. A18A7b0058 (Singapore). B.L. also acknowledges support from the Russian Ministry of Education and Science (No. 14.W03.31.0008). A.E.M. acknowledges the support from the Australian Research Council (No. DP170103778) and the UNSW Scientia Fellowship. J.A.S.-G. acknowledges partial financial support from the Spanish Ministerio de Ciencia, Innovación y Universidades through Grants NANOTOPO (No. FIS2017-91413-EXP) and MELODIA (Nos. PGC2018-095777-B-C21 and MCIU/AEI/FEDER, UE)

Hybrid anapole modes of high-index dielectric nanoparticles

We investigate the peculiarities of light scattering from subwavelength particles made of high-refractive-index materials caused by the coexistence of particular anapole modes of both electric and magnetic character. The similarities and differences of such anapole modes are discussed in detail. We also show that these two types of anapole modes can be supported simultaneously by subwavelength high-index spherical dielectric particles

Fano Resonances: A Discovery that Was Not Made 100 Years Ago

Scattering: We have missed the presence of resonant scattering behavior in the Rayleigh region for years, but a clue was lurking in quantum theory