150 research outputs found
Waveguide properties of single subwavelength holes demonstrated with radially and azimuthally polarized light
We investigate the transmission of focused beams through single subwavelength
holes in a silver film. We use radially and azimuthally polarized light,
respectively, to excite higher order waveguide modes as well as to match the
radial symmetry of the aperture geometry. Remarkably, the transmission
properties can be described by a classical waveguide model even for thicknesses
of the silver film as thin as a quarter of a wavelength
Towards fully integrated photonic displacement sensors
Funding: European Union Horizon 2020 research and innovation programme under the Future and Emerging Technologies Open grant agreement Super-pixels No 829116.The field of optical metrology with its high precision position, rotation and wavefront sensors represents the basis for lithography and high resolution microscopy. However, the on-chip integration a task highly relevant for future nanotechnological devices necessitates the reduction of the spatial footprint of sensing schemes by the deployment of novel concepts. A promising route towards thisgoal is predicated on the controllable directional emission of the fundamentally smallest emitters of light, i.e. dipoles, as an indicator. Here we realize an integrated displacement sensor based on the directional emission of Huygens dipoles excited in an individual dipolar antenna. The position of the antenna relative to the excitation field determines its directional coupling into a six-way crossing of photonic crystal waveguides. In our experimental study supported by theoretical calculations, we demonstrate the first prototype of an integrated displacement sensor with a standard deviation of the position accuracy below λ=300 at room temperature and ambient conditions.Publisher PDFPeer reviewe
On the experimental investigation of the electric and magnetic response of a single nano-structure
We demonstrate an experimental method to separately test the optical response
of a single sub-wavelength nano-structure to tailored electric and magnetic
field distributions in the optical domain. For this purpose a highly focused
y-polarized TEM10-mode is used which exhibits spatially separated longitudinal
magnetic and transverse electric field patterns. By displacing a single
sub-wavelength nano-structure, namely a single split-ring resonator (SRR), in
the focal plane, different coupling scenarios can be achieved. It is shown
experimentally that the single split-ring resonator tested here responds
dominantly as an electric dipole. A much smaller but yet statistically
significant magnetic dipole contribution is also measured by investigating the
interaction of a single SRR with a magnetic field component perpendicular to
the SRR plane (which is equivalent to the curl of the electric field) as well
as by analyzing the intensity and polarization distribution of the scattered
light with high spatial resolution. The developed experimental setup as well as
the measurement techniques presented in this paper are a versatile tool to
investigate the optical properties of single sub-wavelength nano-structures.Comment: 19 pages, 9 figures, accepted by Optics Expres
Hybrid-Entanglement in Continuous Variable Systems
Entanglement is one of the most fascinating features arising from
quantum-mechanics and of great importance for quantum information science. Of
particular interest are so-called hybrid-entangled states which have the
intriguing property that they contain entanglement between different degrees of
freedom (DOFs). However, most of the current continuous variable systems only
exploit one DOF and therefore do not involve such highly complex states. We
break this barrier and demonstrate that one can exploit squeezed cylindrically
polarized optical modes to generate continuous variable states exhibiting
entanglement between the spatial and polarization DOF. We show an experimental
realization of these novel kind of states by quantum squeezing an azimuthally
polarized mode with the help of a specially tailored photonic crystal fiber
Experimental cross-polarization detection of coupling far-field light to highly confined plasmonic gap modes via nanoantennas
We experimentally demonstrate the coupling of far-field light to highly
confined plasmonic gap modes via connected nanoantennas. The excitation of
plasmonic gap modes is shown to depend on the polarization, position and
wavelength of the incident beam. Far-field measurements performed in crossed
polarization allow for the detection of extremely weak signals re-emitted from
gap waveguides and can increase the signal-to-noise ratio dramatically.Comment: 5 figures; http://apl.aip.org
Shaping Field Gradients for Nanolocalization
Deep sub-wavelength localization and displacement sensing of optical nanoantennas have emerged as extensively pursued objectives in nanometrology, where focused beams serve as high-precision optical rulers while the scattered light provides an optical readout. Here, we show that in these schemes using an optical excitation as a position gauge implies that the sensitivity to displacements of a nanoantenna depends on the spatial gradients of the excitation field. Specifically, we explore one of such novel localization schemes based on appearance of transversely spinning fields in strongly confined optical beams, resulting in far-field segmentation of left- and right-hand circular polarizations of the scattered light, an effect known as the giant spin-Hall effect of light. We construct vector beams with augmented transverse spin density gradient in the focal plane and experimentally confirm enhanced sensitivity of the far-field spin-segmentation to lateral displacements of an electric-dipole nanoantenna. We conclude that sculpturing of electromagnetic field gradients and intelligent design of scatterers pave the way towards future improvements in displacement sensitivity
Hybrid Orthorhombic Carbon Flakes Intercalated with Bimetallic Au-Ag Nanoclusters: Influence of Synthesis Parameters on Optical Properties
Until recently, planar carbonaceous structures such as graphene did not show any birefringence under normal incidence. In contrast, a recently reported novel orthorhombic carbonaceous structure with metal nanoparticle inclusions does show intrinsic birefringence, outperforming other natural orthorhombic crystalline materials. These flake-like structures self-assemble during a laser-induced growth process. In this article, we explore the potential of this novel material and the design freedom during production. We study in particular the dependence of the optical and geometrical properties of these hybrid carbon-metal flakes on the fabrication parameters. The influence of the laser irradiation time, concentration of the supramolecular complex in the solution, and an external electric field applied during the growth process are investigated. In all cases, the self-assembled metamaterial exhibits a strong linear birefringence in the visible spectral range, while the wavelength-dependent attenuation was found to hinge on the concentration of the supramolecular complex in the solution. By varying the fabrication parameters one can steer the shape and size of the flakes. This study provides a route towards fabrication of novel hybrid carbon-metal flakes with tailored optical and geometrical properties
The photonic wheel - demonstration of a state of light with purely transverse angular momentum
In classical mechanics, a system may possess angular momentum which can be either transverse (e.g. in a spinning wheel) or longitudinal(e.g. for a spiraling seed falling from a tree) with respect to the direction of motion. However, for light, a typical massless wave system,the situation is less versatile. Photons are well-known to exhibit intrinsic angular momentum which is longitudinal only: the spin angularmomentum defining the polarization and the orbital angular momentum associated with a spiraling phase front. Here we show that itis possible to generate a novel state of the light field that contains purely transverse angular momentum, the analogue of a spinningmechanical wheel. We realize this state by tight focusing of a polarization tailored light beam and measure it using an optical nano-probingtechnique. Such a novel state of the light field can find applications in optical tweezers and spanners where it allows for additionalrotational degree of freedom not achievable in single-beam configurations so far
Chiroptical response of a single plasmonic nanohelix
We investigate the chiroptical response of a single plasmonic nanohelix
interacting with a weakly-focused circularly-polarized Gaussian beam. The
optical scattering at the fundamental resonance is characterized
experimentally, and the chiral behavior of the nanohelix is explained based on
a multipole analysis. The angularly resolved emission of the excited nanohelix
is verified experimentally and it validates the theoretical results. Further,
we study the first higher-order resonance and explain the formation of chiral
dipoles in both cases.Comment: 15 pages, 11 figue
Enhanced spin-orbit coupling in an epsilon-near-zero material
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