Focused vortex-beam generation using gap-surface plasmon metasurfaces

Gap plasmon-based metasurfaces for total control of reflected light

In the quest to miniaturise photonics, it is of paramount importance to control light at the nanoscale. We reveal the main physical mechanism responsible for operation of gap plasmon-based gradient metasurfaces, comprising a periodic arrangement of metal nanobricks, and suggest that two degrees of freedom in the nanobrick geometry allow one to independently control the reflection phases of orth...

Imaging of terahertz surface plasmon waves excited on a gold surface by a focused beam.

Surface plasmon polariton (SPP) waves formed near a tightly focused THz beam on a metallic surface are detected by an integrated sub-wavelength aperture THz near-field probe. The probe allows mapping the electric field pattern of the SPP wave and tracking the SPP propagation from the center of the focal spot. The SPP nature of the observed wave is confirmed by time-resolved measurements. Analys...

Surface-plasmon holographic beam shaping.

Surface plasmon polaritons and free-space beams are often coupled through periodic gratings. Here we show that by employing holographic-based techniques for modulating the grating, one can systematically control the amplitude and phase of the free-space beam. Alternatively, arbitrarily shaped surface plasmon can be generated. By using gratings with different periods for the input and output cou...

Vortex beams with strong longitudinally polarized magnetic field and their generation by using metasurfaces

A novel method of generation and synthesis of azimuthally E-polarized vortex beams is presented. Along the beam axis such beams have a strong longitudinally polarized magnetic field where ideally there is no electric field. We show how these beams can be constructed through the interference of Laguerre–Gaussian beams carrying orbital angular momentum (OAM), and then quantify the longitudinal ma...

Optomechanical beam steering by surface plasmon nanoantenna