669 research outputs found
Interplay of magnetic responses in all-dielectric oligomers to realize magnetic Fano resonances
We study the interplay between collective and individual optically-induced
magnetic responses in quadrumers made of identical dielectric nanoparticles.
Unlike their plasmonic counterparts, all-dielectric nanoparticle clusters are
shown to exhibit multiple dimensions of resonant magnetic responses that can be
employed for the realization of anomalous scattering signatures. We focus our
analysis on symmetric quadrumers made from silicon nanoparticles and verify our
theoretical results in proof-of-concept radio frequency experiments
demonstrating the existence of a novel type of magnetic Fano resonance in
nanophotonics.Comment: 20 pages, 7 figure
Unidirectional and diffractionless surface plasmon-polaritons on three-dimensional nonreciprocal plasmonic platforms
Light-matter interactions in conventional nanophotonic structures typically
lack directionality. Furthermore, surface waves supported by conventional
material substrates do not usually have a preferential direction of
propagation, and their wavefront tends to spread as it propagates along the
surface, unless the surface or the excitation are properly engineered and
structured. In this article, we theoretically demonstrate the possibility of
realizing \emph{unidirectional and diffractionless surface-plasmon-polariton
modes} on a nonreciprocal platform, namely, a gyrotropic magnetized plasma.
Based on a rigorous Green function approach, we provide a comprehensive and
systematic analysis of all the available physical mechanisms that may bestow
the system with directionality, both in the sense of one-way excitation of
surface waves, and in the sense of directive diffractionless propagation along
the surface. The considered mechanisms include (i) the effect of strong and
weak forms of nonreciprocity, (ii) the elliptic-like or hyperbolic-like
topology of the modal dispersion surfaces, and (iii) the source polarization
state, with the associated possibility of chiral surface-wave excitation
governed by angular-momentum matching. We find that three-dimensional
gyrotropic plasmonic platforms support a previously-unnoticed wave-propagation
regime that exhibit several of these physical mechanisms simultaneously,
allowing us to theoretically demonstrate, for the first time, unidirectional
surface-plasmon-polariton modes that propagate as a single ultra-narrow
diffractionless beam. We also assess the impact of dissipation and nonlocal
effects. Our theoretical findings may enable a new generation of plasmonic
structures and devices with highly directional response
Zeeman gyrotropic scatterers: Resonance splitting, anomalous scattering, and embedded eigenstates
Anomalous scattering effects (invisibility, superscattering, Fano resonances, etc) enabled by complex media and metamaterials
have been the subject of intense efforts in the past couple of decades. In this article, we present a full analysis of
the unusual and extreme scattering properties of an important class of complex scatterers, namely, gyrotropic cylindrical
bodies, including both homogeneous and core–shell configurations. Our study unveils a number of interesting effects,
including Zeeman splitting of plasmonic scattering resonances, tunable gyrotropy-induced rotation of dipolar radiation
patterns as well as extreme Fano resonances and non-radiating eigenmodes (embedded eigenstates) of the gyrotropic
scatterer. We believe that these theoretical findings may enable new opportunities to control and tailor scattered fields
beyond what is achievable with isotropic reciprocal objects, being of large significance for different applications, from
tunable directive nano-antennas to selective chiral sensors and scattering switches, as well as in the context of nonreciprocal
and topological metamaterial
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