3 research outputs found
Magnetic Control of the Chiroptical Plasmonic Surfaces
A major challenge
facing plasmon nanophotonics is the poor dynamic
tunability. A functional nanophotonic element would feature the real-time
sizable tunability of transmission, reflection of light’s intensity
or polarization over a broad range of wavelengths, and would be robust
and easy to integrate. Several approaches have been explored so far
including mechanical deformation, thermal, or refractive index effects,
and all-optical switching. Here we devise an ultrathin chiroptical
surface, built on two-dimensional nanoantennas, where the chiral light
transmission is controlled by the externally applied magnetic field.
The magnetic field-induced modulation of the far-field chiroptical
response with this surface exceeds 100% in the visible and near-infrared
spectral ranges, opening the route for nanometer-thin magnetoplasmonic
light-modulating surfaces tuned in real time and featuring a broad
spectral response
Scanning Probe Photonic Nanojet Lithography
The
use of nano/microspheres or beads for optical nanolithography is a
consolidated technique for achieving subwavelength structures using
a cost-effective approach; this method exploits the capability of
the beads to focus electromagnetic waves into subwavelength beams
called photonic nanojets, which are used to expose the photoresist
on which the beads are placed. However, this technique has only been
used to produce regular patterns based on the spatial arrangement
of the beads on the substrate, thus considerably limiting the pool
of applications. Here, we present a novel microsphere-based optical
lithography technique that offers high subwavelength resolution and
the possibility of generating any arbitrary pattern. The presented
method consists of a single microsphere embedded in an AFM cantilever,
which can be controlled using the AFM motors to write arbitrary patterns
with subwavelength resolution (down to 290 nm with a 405 nm laser).
The performance of the proposed technique can compete with those of
commercial high-resolution standard instruments, with the advantage
of a one-order-of-magnitude reduction in costs. This approach paves
the way for direct integration of cost-effective, high-resolution
optical lithography capabilities into several existing AFM systems
Anisotropic Nanoantenna-Based Magnetoplasmonic Crystals for Highly Enhanced and Tunable Magneto-Optical Activity
We present a novel concept of a magnetically
tunable plasmonic crystal based on the excitation of Fano lattice
surface modes in periodic arrays of magnetic and optically anisotropic
nanoantennas. We show how coherent diffractive far-field coupling
between elliptical nickel nanoantennas is governed by the two in-plane,
orthogonal and spectrally detuned plasmonic responses of the individual
building block, one directly induced by the incident radiation and
the other induced by the application of an external magnetic field.
The consequent excitation of magnetic field-induced Fano lattice surface
modes leads to highly tunable and amplified magneto-optical effects
as compared to a continuous film or metasurfaces made of disordered
noninteracting magnetoplasmonic anisotropic nanoantennas. The concepts
presented here can be exploited to design novel magnetoplasmonic sensors
based on coupled localized plasmonic resonances, and nanoscale metamaterials
for precise control and magnetically driven tunability of light polarization
states