Coherence and aberration effects in surface plasmon polariton imaging

Directional Plasmonic Excitation by Helical Nanotips

The phenomenon of coupling between light and surface plasmon polaritons requires specific momentum matching conditions. In the case of a single scattering object on a metallic surface, such as a nanoparticle or a nanohole, the coupling between a broadband effect, i.e., scattering, and a discrete one, such as surface plasmon excitation, leads to Fano-like resonance lineshapes. The necessary phase matching requirements can be used to engineer the light–plasmon coupling and to achieve a directional plasmonic excitation. Here, we investigate this effect by using a chiral nanotip to excite surface plasmons with a strong spin-dependent azimuthal variation. This effect can be described by a Fano-like interference with a complex coupling factor that can be modified thanks to a symmetry breaking of the nanostructure.

Directional light beams by design from electrically driven elliptical slit antennas

We report on the low-energy, electrical generation of light beams in specific directions from planar elliptical microstructures. The emission direction of the beam is determined by the microstructure eccentricity. A very simple, broadband, optical antenna design is used, which consists of a single elliptical slit etched into a gold film. The light beam source is driven by an electrical nanosource of surface plasmon polaritons (SPP) that is located at one focus of the ellipse. In this study, SPPs are generated through inelastic electron tunneling between a gold surface and the tip of a scanning tunneling microscope.

Spin-orbital angular momentum tomography of a chiral plasmonic lens using leakage radiation microscopy

Based on the spin-dependent directional coupling of surface plasmons (SPs) by ∧-shaped antennas, ring-shaped structures built with such antennas have potential applications for optical tweezers and optical switch technology. In this Letter, we introduce an optical method for realizing a complete polarization tomography of coupled SP fields by such a chiral-planar structure. We use a far-field optical approach, namely leakage radiation microscopy (LRM), to map the SPs propagation and polarization. Here, we fully analyze the polarization state of the generated SPs inside the vortex lens structure. In addition, we provide a theoretical model which agrees well with the experimental results.

Spatio-temporal second-order quantum correlations of surface plasmon polaritons

We present an experimental methodology to observe spatio-temporal second-order quantum coherence of surface plasmon polaritons which are emitted by nitrogen vacancy color centers attached at the apex of an optical tip. The approach relies on leakage radiation microscopy in the Fourier space, and we use this approach to test wave-particle duality for surface plasmon polaritons.