268 research outputs found
Radially Self-Accelerating Beams
We report on optical non-paraxial beams that exhibit a self-accelerating
behavior in radial direction. Our theory shows that those beams are solutions
to the full scalar Helmholtz equation and that they continuously evolve on
spiraling trajectories. We provide a detailed insight into the theoretical
origin of the beams and verify our findings on an experimental basis
Substrate-induced bianisotropy in metamaterials
We demonstrate that the presence of a supporting substrate can break the
symmetry of a metamaterial structure, changing the symmetry of its effective
parameters, and giving rise to bianisotropy. This indicates that
magneto-electric coupling will occur in all metamaterials fabricated on a
substrate, including those with symmetric designs
Tunable fishnet metamaterials infiltrated by liquid crystals
We analyze numerically the optical response and effective macroscopic
parameters of fishnet metamaterials infiltrated with a nematic liquid crystal.
We show that even a small amount of liquid crystal can provide tuning of the
structures due to reorientation of the liquid crystal director. This enables
switchable optical metamaterials, where the refractive index can be switched
from positive to negative by an external field. This tuning is primarily
determined by the shift of the cut-off wavelength of the holes, with only a
small influence due to the change in plasmon dispersio
Generation and near-field imaging of Airy surface plasmons
We demonstrate experimentally the generation and near-field imaging of
nondiffracting surface waves - plasmonic Airy beams, propagating on the surface
of a gold metal film. The Airy plasmons are excited by an engineered nanoscale
phase grating, and demonstrate significant beam bending over their propagation.
We show that the observed Airy plasmons exhibit self-healing properties,
suggesting novel applications in plasmonic circuitry and surface optical
manipulation.Comment: 4 pages, 4 figure
Electro-optical switching by liquid-crystal controlled metasurfaces
We study the optical response of a metamaterial surface created by a lattice
of split-ring resonators covered with a nematic liquid crystal and demonstrate
millisecond timescale switching between electric and magnetic resonances of the
metasurface. This is achieved due to a high sensitivity of liquid-crystal
molecular reorientation to the symmetry of the metasurface as well as to the
presence of a bias electric field. Our experiments are complemented by
numerical simulations of the liquid-crystal reorientation.Comment: 6 pages, 3 figure
Manipulation of Airy surface plasmon beams
We demonstrate experimentally the manipulation of Airy surface plasmon beams in a linear potential. For this purpose, we fabricate dielectric-loaded plasmonic structures with a graded refractive index by negative-tone gray-scale electron beam lithography. Using such carefully engineered potentials, we show that the bending of an Airy surface plasmon beam can be fully reversed by the potential.We acknowledge support from the Australian Research
Council and the Australian National Computational
Infrastructure
Observation of optical azimuthons
We observe experimentally optical azimuthons, a generic
class of ring-shaped localised spiralling beams with azimuthal modulation,
carrying phase dislocation in self-focusing nonlinear media. We observe
three- and four-lobe azimuthons in 87Rb vapours and demonstrate their
anomalous rotation controlled by the input phase distribution
Generation and Near-Field Imaging of Airy Surface Plasmons
We demonstrate experimentally the generation and near-field imaging of nondiffracting surface waves, plasmonic Airy beams, propagating on the surface of a gold metal film. The Airy plasmons are excited by an engineered nanoscale phase grating, and demonstrate significant beam bending over their propagation. We show that the observed Airy plasmons exhibit self-healing properties, suggesting novel applications in plasmonic circuitry and surface optical manipulation
Measurement of scaling laws for shock waves in thermal nonlocal media
We are able to detect the details of spatial optical collisionless
wave-breaking through the high aperture imaging of a beam suffering shock in a
fluorescent nonlinear nonlocal thermal medium. This allows us to directly
measure how nonlocality and nonlinearity affect the point of shock formation
and compare results with numerical simulations.Comment: 4 pages, 4 figure
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