30 research outputs found
Optical chirality without optical activity: How surface plasmons give a twist to light
Light interacts differently with left and right handed three dimensional
chiral objects, like helices, and this leads to the phenomenon known as optical
activity. Here, by applying a polarization tomography, we show experimentally,
for the first time in the visible domain, that chirality has a different
optical manifestation for twisted planar nanostructured metallic objects acting
as isolated chiral metaobjects. Our analysis demonstrate how surface plasmons,
which are lossy bidimensional electromagnetic waves propagating on top of the
structure, can delocalize light information in the just precise way for giving
rise to this subtle effect.Comment: Opt. Express 16, 12559 (2008
Metadevice for intensity modulation with sub-wavelength spatial resolution
Effectively continuous control over propagation of a beam of light requires light modulation with pixelation that is smaller than the optical wavelength. Here we propose a spatial intensity modulator with sub-wavelength resolution in one dimension. The metadevice combines recent advances in reconfigurable nanomembrane metamaterials and coherent all-optical control of metasurfaces. It uses nanomechanical actuation of metasurface absorber strips placed near a mirror in order to control their interaction with light from perfect absorption to negligible loss, promising a path towards dynamic beam diffraction, light focusing and holography without unwanted diffraction artefacts
Polarization conversion and “focusing” of light propagating through a small chiral hole in a metallic screen
Propagation of light through a thin flat metallic screen containing a hole of twisted shape is sensitive to whether the incident wave is left or right circularly polarized. The transmitted light accrues a component with handedness opposite to the incident wave. The efficiency of polarization conversion depends on the mutual direction of the hole’s twist and the incident light’s wave polarization handedness and peaks at a wavelength close to the hole overall size. We also observed strong transmitted field concentration at the center of he chiral hole when the handedness of the chiral hole and the wave’s polarization state are the same
Active Control of Sound Radiated by a Submarine Hull in Bending Vibration Using Inertial Actuators
A fast-growing larch stand in an area subjected to air pollution, situated in the Ore Mountains
Zu den Beziehungen zwischen Boden, Ernährungszustand und Wuchsleistung bei Lärche (Larix decidua Mill.)
Plasmonic Ratchet Wheels: Switching Circular Dichroism by Arranging Chiral Nanostructures
We demonstrate circular dichroism (CD) in the second harmonic generation (SHG) signal from chiral assemblies of G-shaped nanostructures made of gold. The arrangement of the G shapes is crucial since upon reordering them the SHG-CD effect disappears. Microscopy reveals SHG "hotspots" assemblies, which originate in enantiomerically sensitive plasmon modes, having the novel property of exhibiting a chiral geometry themselves in relation with the handedness of the material. These results open new frontiers in studying chirality