Controlling Light Polarization from Helical Travelling-Wave Nanoantennas

Light polarization is a key factor of modern photonics. Tailoring surface plasmons (SPs) in anisotropically-shaped metallic nanostructures introduces the prospect of polarization control at small scale [1]. However, the resulting components remain much larger than the wavelength of light. Here, we present a travelling-wave helical plasmonic antenna (TW-HPA) that overcomes this limit [2]. Due to its non-resonant nature, it differs from existing helical plasmonic structures [3-5], thus extending the concept of travelling-wave helical antenna [6] to optics.