Chiral plasmonics of self-assembled nanorod dimers

Chiral nanoscale photonic systems typically follow either tetrahedral or helical geometries that require four or more different constituent nanoparticles. Smaller number of particles and different chiral geometries taking advantage of the self-organization capabilities of nanomaterials will advance understanding of chiral plasmonic effects, facilitate development of their theory, and stimulate practical applications of chiroplasmonics. Here we show that gold nanorods self-assemble into side-by-side orientated pairs and ‘‘ladders’’ in which chiral properties originate from the small dihedral angle between them. Spontaneous twisting of one nanorod versus the other one breaks the centrosymmetric nature of the parallel assemblies. Two possible enantiomeric conformations with positive and negative dihedral angles were obtained with different assembly triggers. The chiral nature of the angled nanorod pairs was confirmed by 4p full space simulations and the first example of single-particle CD spectroscopy. Self-assembled nanorod pairs and ‘‘ladders’’ enable the development of chiral metamaterials, (bio)sensors, and new catalytic processes

Octave-wide photonic band gap in three-dimensional plasmonic Bragg structures and limitations of radiative coupling

Radiative coupling between oscillators is one of the most fundamental subjects of research in optics, where particularly a Bragg-type arrangement is of interest and has already been applied to atoms and excitons in quantum wells. Here we explore this arrangement in a plasmonic structure. We observe the emergence of an octave-wide photonic band gap in the optical regime. Compared with atomic or excitonic systems, the coupling efficiency of the particle plasmons utilized here is several orders of magnitude larger and widely tunable by changing the size and geometry of the plasmonic nanowires. We are thus able to explore the regime where the coupling distance is even limited by the large radiative decay rate of the oscillators. This Bragg-stacked coupling scheme will open a new route for future plasmonic applications such as far-field coupling to quantum emitters without quenching, plasmonic cavity structures and plasmonic distributed gain schemes for spasers

Accurate and convergent T-matrix calculations of light scattering by spheroids

The convergence behavior of the T-matrix method as calculated by the extended boundary condition method (EBCM) is studied, in the case of light scattering by spheroidal particles. By making use of a new formulation of the EBCM integrals specifically designed to avoid numerical cancellations, we are able to obtain accurate matrices up to high multipole order, and study the effect of changing this order on both the individual matrix elements and derived physical observables. Convergence of near- and far-field scattering properties with a relative error of 10−15 is demonstrated over a large parameter space in terms of size, aspect ratio, and particle refractive index. This study demonstrates the capability of the T-matrix/EBCM method for fast, efficient, and numerically stable electromagnetic calculations on spheroidal particles with an accuracy comparable to Mie theory

Ultra-low chromatic dispersion measurement of optical fibers with a tunable cw fiber laser

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Enhanced Electron Photoemission by Collective Lattice Resonances in Plasmonic Nanoparticle-Array Photodetectors and Solar Cells

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Optical Tamm states at the interface between a photonic crystal and an epsilon-near-zero nanocomposite

Текст статьи не публикуется в открытом доступе в соответствии с политикой журнала.The spectral properties of a one-dimensional photonic crystal bounded with a resonance- absorbing nanocomposite layer are investigated. The bulk concentrations of metal nanoparticles dispersed in a transparent nanocomposite matrix are determined at which the effective permittivity takes near-zero values. The transmission, reflection and absorption spectra of the investigated structures at the normal incidence of light are calculated. The demonstrated possibility of formation of the optical Tamm states at the interface between the photonic crystal and nanocomposite is ensured by the near-zero real and imaginary parts of the permittivity or only the imaginary part of the permittivity at the zero real part. The specific features of field localization at the optical Tamm state frequencies are examined