102 research outputs found
Multipolar third-harmonic generation driven by optically-induced magnetic resonances
We analyze third-harmonic generation from high-index dielectric nanoparticles
and discuss the basic features and multipolar nature of the parametrically
generated electromagnetic fields near the Mie-type optical resonances. By
combining both analytical and numerical methods, we study the nonlinear
scattering from simple nanoparticle geometries such as spheres and disks in the
vicinity of the magnetic dipole resonance. We reveal the approaches for
manipulating and directing the resonantly enhanced nonlinear emission with
subwavelength all-dielectric structures that can be of a particular interest
for novel designs of nonlinear optical antennas and engineering the magnetic
optical nonlinear response at nanoscale.Comment: 24 pages, 6 figure
Tunable nonlinear graphene metasurfaces
We introduce the concept of nonlinear graphene metasurfaces employing the
controllable interaction between a graphene layer and a planar metamaterial.
Such hybrid metasurfaces support two types of subradiant resonant modes,
asymmetric modes of structured metamaterial elements ("metamolecules") and
graphene plasmons exhibiting strong mutual coupling and avoided dispersion
crossing. High tunability of graphene plasmons facilitates strong interaction
between the subradiant modes, modifying the spectral position and lifetime of
the associated Fano resonances. We demonstrate that strong resonant
interaction, combined with the subwavelength localization of plasmons, leads to
the enhanced nonlinear response and high efficiency of the second-harmonic
generation.Comment: 6 pages, 5 figure
Parity anomaly laser
We propose a novel supersymmetry-inspired scheme for achieving robust single
mode lasing in arrays of coupled microcavities, based on factorizing a given
array Hamiltonian into its "supercharge" partner array. Pumping a single
sublattice of the partner array preferentially induces lasing of an unpaired
zero mode. A chiral symmetry protects the zero mode similar to 1D topological
arrays, but it need not be localized to domain walls or edges. We demonstrate
single mode lasing over a wider parameter regime by designing the zero mode to
have a uniform intensity profile.Comment: Published version. 5 pages, 6 figure
Nonlocal response of Mie-resonant dielectric particles
Mie-resonant high-index dielectric particles are at the core of modern
all-dielectric photonics. In many situations, their response to the external
fields is well-captured by the dipole model which neglects the excitation of
higher-order multipoles. In that case, it is commonly assumed that the dipole
moments induced by the external fields are given by the product of particle
polarizability tensor and the field in the particle center. Here, we
demonstrate that the dipole response of non-spherical subwavelength dielectric
particles is significantly more complex since the dipole moments are defined
not only by the field in the particle center but also by the second-order
spatial derivatives of the field. As we prove, such nonlocal response is
especially pronounced in the vicinity of anapole minimum in the scattering
cross-section. We examine the excitation of high-index dielectric disk in
microwave domain and silicon nanodisk in near infrared applying
group-theoretical analysis and retrieving the nonlocal corrections to the
dipole moments. Extending the discrete dipole model to include nonlocality of
the dipole response, we demonstrate an improved agreement with full-wave
numerical simulations. These results provide important insights into
meta-optics of Mie-resonant non-spherical particles as well as metamaterials
and metadevices based on them.Comment: 12 pages, 6 figure
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